# Comparison of Three Sampling Methods for Estimating Grasshopper (Orthoptera, Acrididea) Assemblages in African Rainforests

Charly Oumarou Ngoute, Philène C. A. Um Nyobe, Sévilor Kekeunou, Michel Lecoq

► To cite this version:

Charly Oumarou Ngoute, Philène C. A. Um Nyobe, Sévilor Kekeunou, Michel Lecoq. Comparison of Three Sampling Methods for Estimating Grasshopper (Orthoptera, Acrididea) Assemblages in African Rainforests. PSYCHE, 2025, 2025, pp.8857340. 10.1155/psyc/8857340. hal-05206942

HAL Id: hal-05206942

https://hal.inrae.fr/hal-05206942v1

Submitted on 11 Aug 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

Research Article

# Comparison of Three Sampling Methods for Estimating Grasshopper (Orthoptera, Acrididea) Assemblages in African Rainforests

Charly Oumarou Ngoute ID<fnref n="1" />, Philène C. A. Um Nyobe ID<fnref n="2" />, Sévilor Kekeunou ID<fnref n="3" />, and Michel Lecoq ID<fnref n="4" />,<fnref n="5" />

Correspondence should be addressed to Charly Oumarou Ngoute; coumaroungoute@yahoo.fr

Received 3 March 2025; Revised 16 June 2025; Accepted 10 July 2025

Academic Editor: Ai-Ping Liang

Copyright © 2025 Charly Oumarou Ngoute et al. Psyche: A Journal of Entomology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Grasshoppers are essential components of terrestrial ecosystems, playing major roles in biodiversity and ecological balance. Assessing grasshopper diversity in specific regions is crucial for understanding species coexistence, supporting sustainable agriculture, and informing conservation efforts. Reliable and standardized survey methods are fundamental to this field. Sweep net sampling is widely recognized as the fastest and most commonly used method globally. This study presents the comparative assessment of three sampling methods for estimating grasshopper assemblages in African rainforests: 30 min of random net sweeping, 1 m<fnref n="2" /> open quadrat sampling, and pitfall trapping. These methods were evaluated across two distinct ecological zones, fallow land, and forest. Results show that net sampling is the most effective method for estimating grasshopper diversity in these environments. However, incorporating quadrat sampling and pitfall trapping enhances species diversity assessment. Net sweeping is particularly efficient for collecting winged species in short vegetation, while quadrat sampling and pitfall trapping are better suited for species dwelling in the undergrowth and forest litter. A combine approach incorporating multiple sampling methods provides a more comprehensive assessment of grasshopper diversity, overcoming the limitations of sweeping alone.

**Keywords:** Acridomorpha; diversity; fallow land; forest; sampling; species abundance; species richness

## 1. Introduction

Grasshoppers are a large group of insects, playing an important role in terrestrial ecosystems including nutrient cycling and the food web [1, 2]. They are frequently utilized as model organisms in ecological studies due to their significance as primary and secondary consumers, making them an important part of the arthropod communities. Additionally, grasshoppers are often used to monitor the

effects of human-induced land-use changes [3]. As highly sensitive bioindicators, grasshoppers respond quickly to environmental changes, offering valuable insights into ecosystem health [4, 5]. These insects thrive in diverse habitats, occupying important ecological niches across various climates and vegetation structures [6]. Investigating grasshopper diversity in specific regions is essential for understanding species coexistence, supporting sustainable agriculture and ecology, and conserving biodiversity [6].

<footnote n="1">¹Department of Biology of Animal Organisms, University of Douala, Douala, Cameroon</footnote>

<footnote n="2">²Department of Rural Engineering, National Advanced School of Public Works of Yaoundé, Yaoundé, Cameroon</footnote>

<footnote n="3">³Department of Animal Biology and Physiology, University of Yaoundé 1, Yaoundé, Cameroon</footnote>

<footnote n="4">⁴UMR CBGP, CIRAD, Montpellier, France</footnote>

<footnote n="5">⁵CBGP SupAgro, University of Montpellier, Montpellier, France</footnote>
Developing robust and standardized methods for conducting grasshopper surveys remains a key priority in advancing research on species diversity [5].

Studying species diversity is essential for understanding the composition of communities, maintaining the structure of ecosystem, and ensuring their stability [7]. The distribution patterns and maintenance mechanisms of insect species represent key areas of focus in insect ecology [8]. Several factors influence species diversity patterns, including temperature, water availability, soil properties, plant diversity, and habitat heterogeneity [6, 9, 10]. Biotic surveys provide basic information to address a variety of questions in ecology and environmental management. Numerous sampling methods are available for collecting biological data, and the choice of method often depends on the specific objectives of a project, the availability of equipment, cost considerations, and familiarity with the techniques [11–17]. Accurately answering questions in community ecology and assessing the overall biological condition of ecosystems require comprehensive characterization of the entire assemblages [14, 18].

Ecologists have extensively studied grasshopper richness and density across a wide range of ecosystems. To objectively determine grasshopper population sizes, mark-release-recapture techniques have been employed, providing data on the total number of individuals per unit area (e.g., [19–23]). However, these methods are time-consuming and impractical for anything other than small-scale studies [24, 25]. Consequently, subsampling strategies are necessary to ensure adequate coverage of survey sites when estimating population sizes [26]. A variety of sampling techniques have been developed to assess grasshopper diversity, with sweep netting, quadrat counts, acoustic record, and trapping sample being the most commonly employed methods [5, 24, 27–30]. Sweep net sampling is the fastest, least expensive, and most widely used method for determining grasshopper species composition [2, 31–33]. Sweep netting is widely used for sampling insects and other arthropods in vegetation, commonly applied in taxonomic studies, pest monitoring, and ecological research. The method involves a net with a solid frame and fine mesh which is swept through vegetation to capture arthropods resting on or moving through plants within a given habitat. Although sweep netting is one of the most commonly employed techniques in entomology, it has limitations in assessing certain insect groups, underscoring the need for complementary sampling methods. Sweep samples may yield inaccurate estimates of grasshopper community composition when species do not share equal probabilities of being captured [5]. These differences can arise from variation in the distance and trajectory of escape when individuals are flushed, or in the height and speed reached during fly [2, 17]. Some species are difficult to catch because they fly long distances, while others—such as apterous, soil-dwelling taxa—are not flushed at all, making them particularly elusive to net-based sampling. The accuracy of sweep netting could also be influenced by species heterogeneity and density, the structural complexity of the vegetation, and climatic

conditions specific to each ecological zone. In African rainforest environments, alternative sampling methods such as box quadrats, open quadrats, and pitfall traps have been employed to improve the assessment of grasshopper populations [34–39]. The present study, conducted in the Congo basin rainforest, is the first to compare three commonly used sampling methods for estimating grasshopper assemblages: sweep net sampling, open quadrat sampling, and pitfall trapping. This research aimed to address two main questions: (i) Is sweep net sampling still the most effective method for assessing grasshopper species diversity in African rainforests? (ii) What additional value do open quadrat and pitfall trap sampling methods provide in evaluating forest grasshopper assemblages? We hypothesized that (i) sweep net sampling remains the most effective technique for assessing grasshopper assemblages in African rainforest ecosystems and (ii) open quadrat and pitfall trap sampling methods significantly improve estimates of species richness, abundance, and overall diversity.

## 2. Materials and Methods

2.1. *Study Sites.* The study was conducted at three localities on the South Cameroon Plateau: Ngutadjap (Vallée-du-Nètem Division), Ongot (Méfou-et-Akono Division), and Zamakoe (Nyong-et-So'o Division) (Figure 1). The vegetation in this part of Central Africa consists of humid forests, which exhibit varying assemblages influenced by climate and human activities [40–42]. The climate of the South Cameroon Plateau is Guinean, with four distinct seasons—two rainy and two dry [43]—and annual rainfall ranging from 1500 to 2000 mm. The native vegetation is dominated by species from the families Sterculiaceae Vent. 1807 and Ulmaceae Mirb. (1815) plant species [44]. Ongoing human activities such as agriculture and logging are steadily transforming the natural landscape. Following deforestation, fallow lands become dominated by early succession plant species such as *Acalypha australis* L. (1753), *Chromolaena odorata* (L.) King and Rob. 1970, and *Ageratum conyzoides* L. 1753. Major food crops cultivated in the region include cocoa, coffee, cassava, groundnut, plantain, maize, oil palm, sweet banana, and yam. Grasshopper sampling was conducted in both forests and fallow land habitats at each study site.

The three study localities were selected based on their varying levels of forest degradation, allowing for the application of sampling methods across a gradient of forest conditions in this part of the Congo basin. Ongot (14–88 inhabitants/km²), located near Yaoundé—the capital city of Cameroon—represents the most heavily degraded forest area. Zamakoe (10–41 inhabitants/km²), situated near the town of Mbalmayo, is characterized by moderately degraded forests. In contrast, Ngutadjap (2–15 inhabitants/km²), located in the Vallée-du-Nètem division, contains the least degraded or near-pristine forest environments [37–39, 45]. A detailed list of plants species composition in the studied forests and adjacent fallow lands is provided in the online supporting information (Supporting Tables S1 and S2).
(ABC = 110); C, not A, not B (ABC = 001); A and C, not B (ABC = 101); B and C, not A (ABC = 011); A, B, and C (ABC = 111). The distributions of the observed species richness were compared using Spearman's rank correlation (sr) test in PAST software.

### 2.4.2. Abundance, Frequency, and Distribution.
We calculated both absolute and relative abundance. Absolute abundance [65] refers to the total number "n" of individuals of a specific grasshopper species. The relative abundance [65] of each grasshopper species was determined for each sampling method as the ratio of a species' total absolute abundance to the total absolute abundance (Table A1) of all the species within the sampling method. The relative abundance (fx) of a given species was categorized according to Dajoz [64] as follows: fx > 50%, species very abundant; 25% ≤ fx ≤ 50%, species abundant; 1% ≤ fx < 25%, species less abundant; fx < 1%, species rare. Average relative abundance for each vegetation type and sampling method was calculated using PAST software and compared using the Chi-squared (Chi²) test. Species abundance distributions for each sampling method were also visualized in the same software through Box and Jitter plots. These plots depicted the 25th and 75th percentiles (quartiles) as a box, with the median represented by a horizontal line within it. Minimum and maximum values were illustrated using short horizontal lines, or "whiskers." Outlier values were automatically identified, with whiskers extending to the largest data point less than 1.5 times the box height, referred to as the "upper inner fence." The lower whisker followed the same principle, extending to the smallest data point within this range. Data points falling outside the inner fences were displayed as circles, while those exceeding three times the box height, known as the "outer fences," were marked with stars. Quartile calculations were performed using interpolation methods [67]. The mean relative abundance was represented using bar charts, where the mean value was depicted by a bar, and the whisker intervals indicated as a one-sigma range (95% confidence) based on the standard error [67]. Comparisons of species relative abundance distributions were conducted using Spearman's rank correlation test (sr) in PAST software.

### 2.4.3. Diversity.
The Shannon diversity index (H') was calculated using PAST software to quantify the diversity of the grasshopper community sampled by each method across the two vegetation types. A t-test, following the method of Hutcheson [68], was employed to compare H' values between two samples.

## 3. Results

### 3.1. Species Richness.
A total of 43 grasshopper species were collected using the three sampling methods under study (Table A1). This includes 15 Catantopinae Brunner von Wattenwyl, 1893, seven Acridinae MacLeay, 1821, six Pyrgomorphinae Brunner von Wattenwyl, 1874, five Coptacrinae Brunner von Wattenwyl, 1893, three Oedipodinae

Walker, 1871, three Oxyinae Brunner von Wattenwyl, 1893, two Eyprepocnemidinae Brunner von Wattenwyl, 1893, one Cyrtacanthacridinae Kirby, 1910, and one Spathosterninae Rehn, 1957 (Table A1). All grasshopper species were sampled using the sweep nets, while 36 species were collected in the open quadrats, and 24 species were captured in the pitfall traps (Tables 1 and A1).

In the forest ecological zone, six species were exclusively collected using the sweep net, *Gemeneta opilionoides* (Bolivar, 1905), *Gemeneta terrea* Karsch, 1892, *Pteropera cannapi* Ramme, 1929, *Cyphocerastis hopei* Bruner, 1920, *Taphronota ferruginea* (Fabricius, 1781), and *Parapetasia femorata* Bolivar, 1884 (Figure 2(a)). Four other taxa—*Holopercna gerstaeckeri* (Bolivar, 1890), *Apoboleus degener* Karsch, 1891, *Pterotoliltus erythocerus* Rowell and Oumarou-Ngoute, 2024, and *Digentia fasciata* Ramme, 1929—were sampled using both the sweep net and in the open quadrat. Two species, *Mazaea granulosa* Stål, 1876, and *Serpusia opacula* Karsch, 1891, were collected with all three sampling methods (Figure 2(a)). In the fallow land ecological zone, four species were exclusively collected by net: *Roduniella insipida* (Karsch, 1896), *Cyphocerastis tristis* Karsch, 1891, *D. fasciata*, *Taphronota calliparea* (Schaum, 1853). One species, *P. erythocerus*, was sampled only in the open quadrat (Figure 2(b)). Another species, *Trilophidia conturbata* (Walker, 1870), was collected using both the sweep net and in the pitfall trap. Ten species—*H. gerstaeckeri*, *Oxycatantops spissus* (Walker, 1870), *Pteropera descampsi* Donskoff, 1981, *Stenocrobylus festivus* Karsch, 1891, *Cyphocerastis laeta* Karsch, 1891, *Acanthacris ruficornis* (Fabricius, 1787), *Spathosternum pygmaeum* Karsch, 1893, *Morphacris fasciata* (Thunberg, 1815), *Oxya hyla* Serville, 1831, and *T. ferruginea*—were sampled using both net and the open quadrat. The remaining 22 taxa were collected using all three sampling methods (Figure 2(b)). In both the forest and in fallow land ecological zones, no significant correlation was observed between species richness distributions across the three sampling methods (all the *p* values < 0.05) (Figures 3(a) and 3(b)).

### 3.2. Sampling Effort.
The overall grasshopper sampling effort during the study was high, achieving 96.30% efficiency (Table 1). Among the methods, net sampling was the most efficient (94.03%), followed by open quadrat sampling (90.84%) and pitfall trapping (86.98%). The pitfall trap demonstrated greater efficiency in the forest ecological zone (97.56%) compared to the fallow land ecosystem (85.94%). Conversely, net sampling (in forest = 70.62%, in fallow land = 94.75%) and open quadrat sampling (in forest = 81.63%, in fallow land = 88.09%) were more effective in the fallow land ecological zone (Table 1). Rarefaction curves (Figures 4(a) and 4(b)) indicate that, overall, sampling effort was higher in fallow land than that in forest. In the forest, all curves began to plateau toward the end of the sampling period, whereas in fallow land, the curves for net sampling and the cumulative three sampling methods leveled off around 1500 individuals collected (Figures 4(a) and 4(b)).
<table><caption>TABLE 1: Sampling effort and grasshopper diversity across sampling methods and ecological zones.</caption><thead><tr><th rowspan="2">Estimators</th><th rowspan="2">Forest</th><th>Net</th><th rowspan="2">Both</th><th rowspan="2">Forest</th><th>Pitfall trap</th><th rowspan="2">Both</th><th rowspan="2">Forest</th><th>Open quadrat</th><th rowspan="2">Both</th><th rowspan="2">Total</th></tr><tr><th>Fallow land</th><th>Fallow land</th><th>Fallow land</th></tr></thead><tbody><tr><td>Taxa_S</td><td>12</td><td>37</td><td>43</td><td>2</td><td>23</td><td>24</td><td>6</td><td>33</td><td>36</td><td>43</td></tr><tr><td>Individuals</td><td>383</td><td>1987</td><td>2370</td><td>21</td><td>355</td><td>376</td><td>61</td><td>766</td><td>827</td><td>3573</td></tr><tr><td>Shannon H'</td><td>1.85</td><td>3.33</td><td>3.44a</td><td>0.32</td><td>2.42</td><td>2.51b</td><td>0.87</td><td>2.92</td><td>3.00c</td><td>3.24</td></tr><tr><td>ACE</td><td>68.06 (17.63)</td><td>97.41 (37.98)</td><td>96.36 (44.62)</td><td>100 (2.00)</td><td>83.88 (27.42)</td><td>83.74 (28.66)</td><td>76.53 (7.84)</td><td>89.77 (36.76)</td><td>90.56 (39.75)</td><td>97.06 (44.30)</td></tr><tr><td>ICE</td><td>68.14 (17.61)</td><td>97.24 (38.05)</td><td>96.26 (44.67)</td><td>100 (2.00)</td><td>83.88 (27.42)</td><td>83.74 (28.66)</td><td>75.56 (7.94)</td><td>89.94 (36.69)</td><td>90.74 (39.67)</td><td>97.06 (44.30)</td></tr><tr><td>Chao 1</td><td>60.30 (19.90)</td><td>94.29 (39.24)</td><td>94.17 (45.66)</td><td>100 (2.00)</td><td>88.52 (25.98)</td><td>90.39 (26.55)</td><td>92.44 (6.49)</td><td>84.11 (39.23)</td><td>89.64 (40.16)</td><td>97.46 (44.12)</td></tr><tr><td>Chao 2</td><td>60.69 (19.77)</td><td>94.43 (39.18)</td><td>94.25 (45.62)</td><td>100 (2.00)</td><td>88.49 (25.99)</td><td>90.36 (26.56)</td><td>92.44 (6.49)</td><td>84.09 (39.24)</td><td>89.64 (40.16)</td><td>97.46 (44.12)</td></tr><tr><td>Jackknife 1</td><td>75.56 (15.88)</td><td>92.70 (39.91)</td><td>91.60 (46.94)</td><td>100 (2.00)</td><td>79.36 (28.98)</td><td>80.02 (29.99)</td><td>75.09 (7.99)</td><td>86.86 (37.99)</td><td>87.82 (40.99)</td><td>93.49 (45.99)</td></tr><tr><td>Jackknife 2</td><td>64.03 (18.74)</td><td>90.44 (40.91)</td><td>89.67 (47.95)</td><td>95.23 (2.10)</td><td>79.33 (28.99)</td><td>82.75 (29.00)</td><td>66.74 (8.99)</td><td>80.52 (40.98)</td><td>83.74 (42.99)</td><td>95.55 (45.00)</td></tr><tr><td>Bootstrap</td><td>87.78 (13.67)</td><td>96.32 (38.41)</td><td>95.59 (44.98)</td><td>93.89 (2.13)</td><td>88.22 (26.07)</td><td>88.36 (27.16)</td><td>86.70 (6.92)</td><td>93.56 (35.27)</td><td>93.62 (38.45)</td><td>96.11 (44.74)</td></tr><tr><td>MMM</td><td>94.11 (12.75)</td><td>95.58 (38.71)</td><td>94.71 (45.40)</td><td>92.59 (2.16)</td><td>98.71 (23.30)</td><td>99.13 (24.21)</td><td>97.08 (6.18)</td><td>98.36 (33.55)</td><td>98.41 (36.58)</td><td>96.26 (44.67)</td></tr><tr><td>Mean of estimators</td><td>70.62 (16.99)</td><td>94.75 (39.05)</td><td>94.03 (45.73)</td><td>97.56 (2.05)</td><td>85.94 (26.76)</td><td>86.98 (27.59)</td><td>81.63 (7.35)</td><td>88.09 (37.46)</td><td>90.36 (39.84)</td><td>96.30 (44.65)</td></tr></tbody></table>

Note: Values represent sampling effort (%) (and theoretical species richness). Letters a, b, and c denote the results of the Shannon t-test for two samples, with different letters indicating statistically significant differences between values.
<figure><img src="image_3.png" /><figcaption>FIGURE 2: Grasshopper species richness by sampling methods. (a) Forest and (b) fallow land.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>FIGURE 3: Correlation between species richness and between relative abundance distributions across sampling methods. (a) Species richness in forest, (b) species richness in fallow land, (c) relative abundance in forest, and (d) relative abundance in fallow land. Note: Values represent Spearman's (sr) correlation statistics. Pitfall t. = pitfall trap and Open q. = ppen quadrat.</figcaption></figure>

3.3. *Abundance, Frequency, and Distribution.* During our study, the relative abundance distributions of the collected species showed generally low values (Table 2). In the forest ecological zone, 82.35% of grasshopper individuals were captured using net sampling, 13.11% with the open quadrat, and only 4.53% with the pitfall trap. In the fallow land ecological zone, 63.92% of specimens were collected using net sampling, 24.65% with the open quadrat, and 11.42%

with the pitfall trap (Table 2). Both in the forest and fallow land ecological zones, net sampling yielded the highest values of species abundance, with 25-75 percent quartiles of 0.26-4.62 in the forest and 0.41-2.04 in fallow land. This was followed by the open quadrat method, with 25-75 percent quartiles of 0.0-0.58 in the forest and 0.05-0.74 in fallow land, and the pitfall trap, which had 25-75 percent quartiles of no median in the forest and 0.0-0.41 in fallow land
<figure><img src="image_5.png" /><figcaption>FIGURE 4: Species rarefaction curves per sampling methods. (a) Forest and (b) fallow land.</figcaption></figure>

(Figures 5(a) and 5(b)). The median values cited above (Figures 5(a) and 5(b)) differed significantly between sampling methods (forest: *p* = 0.001; fallow land: *p* < 0.0001). Similarly, the mean relative abundances of species (Figures 5(c) and 5(d)) showed statistically significant differences among sampling methods (forest: *p* = 0.01; fallow land: *p* < 0.001). Net sampling had the highest means, with 6.86 ± 5.09 in the forest and 1.68 ± 0.35 in fallow land, followed by the open quadrat (forest: 1.09 ± 0.82; fallow land: 0.65 ± 0.16), and the pitfall trap (forest: 0.37 ± 0.34; fallow land: 0.3 ± 0.09) (Figures 5(c) and 5(d)). Furthermore, no correlations were observed in either ecological zone (all the *p* values < 0.05) between the distributions of the species relative abundance (Figures 3(c) and 3(d)).

**3.4. Diversity.** The Shannon diversity index revealed that net sampling (H' = 3.44) captures the more diverse grasshopper communities compared to the open quadrat (H' = 3.00) and pitfall trap (H' = 2.51) (Table 1). This trend was consistent across both ecological zones studied (Table 1).

## 4. Discussion

**4.1. Species Richness and Sampling Effort.** Our study confirmed the first hypothesis, demonstrating that net sampling yielded the highest species richness and sampling efficiency, while the open quadrat and pitfall trap did not significantly enhance grasshopper species richness. All the 43 grasshopper species studied were captured using net sampling, whereas 36 species were collected with the open quadrat, and only 24 species with the pitfall trap. Sweep netting is the most widely used method for grasshopper sampling worldwide, recognized for its speed and cost-effectiveness in assessing grasshopper communities and determining species composition. The method has been applied in diverse ecological studies, including estimating grasshopper distribution in the Ningxia Hui Autonomous Region of northwestern China [2], monitoring the spatiotemporal dynamics of grasshopper habitats using multisource data and landscape heterogeneity in China [69], assessing grasshopper (Orthoptera: Acridoidea) diversity in the Pampas region of

Argentina [33], examining the influence of ancient and contemporary landscapes on genetic variation in a specialist grasshopper species in Spain [70], estimating the distribution of endemic grasshopper species in the agro-natural landscapes of the Cape Floristic Region in South Africa [71], and studying grasshopper assemblages in forest and savanna ecosystems in the center, west, and southwest regions of Cameroon [35]. However, recent studies have also highlighted the value of alternative methods. Fartmann et al. [30] recommended box quadrats as an effective approach for monitoring Orthoptera species richness and abundance in open habitats. This method has also been successfully integrated into the German insect monitoring scheme for the establishment of a nationwide, long-term Orthoptera survey [29]. These findings collectively suggest that the choice and efficiency of grasshopper sampling methods depend heavily on the eco-climatic context and the structural characteristics of the ecosystems under study. Nearly 2 decades ago, Gardiner et al. [24] demonstrated that sweep netting is particularly effective in areas with short vegetation (< 50 cm) and less efficient in taller, denser vegetation (> 50 cm), where plant structure can obstruct sampling efforts. In the present study, sweep netting yielded the highest species richness in both fallow (open) lands and in forest ecosystems, confirming its continued utility across varied habitat types. This result may be attributed to the low grasshopper densities observed in the two ecological zones studied (< 2 adults per m²), where sweep netting may be more effective for capturing widely dispersed individuals.

**4.2. Abundance and Diversity.** As hypothesized, sweep net sampling yielded the highest grasshopper abundance and diversity. Additionally, open quadrats and pitfall traps contributed approximately 25% of all specimens collected, thereby enhancing the overall assessment of grasshopper communities. Sweep netting is also widely used across sub-Saharan Africa to estimate grasshopper abundance, diversity, and community composition. For instance, it has been employed to assess grasshopper and locust populations across three ecological zones in Nakuru County, Kenya [72], to collect edible orthopterans (grasshoppers,
<table><caption>TABLE 2: Relative abundance (%) of grasshopper species across sampling methods.</caption><thead><tr><th>Species</th><th>Net</th><th>Pitfall trap</th><th>Open quadrat</th><th>Total</th></tr></thead><tbody><tr><td colspan="5"><strong>A. Forest species</strong></td></tr><tr><td>Mazaea granulosa</td><td>62.59</td><td>4.10</td><td>10.11</td><td>76.80</td></tr><tr><td>Serpusia opacula</td><td>6.23</td><td>0.43</td><td>1.51</td><td>8.17</td></tr><tr><td>Holopercna gerstaeckeri</td><td>5.16</td><td>0.00</td><td>0.43</td><td>5.59</td></tr><tr><td>Pterototiltus erythocerus</td><td>3.02</td><td>0.00</td><td>0.21</td><td>3.23</td></tr><tr><td>Digentia fasciata</td><td>1.72</td><td>0.00</td><td>0.64</td><td>2.36</td></tr><tr><td>Pteropera carnapi</td><td>1.07</td><td>0.00</td><td>0.00</td><td>1.07</td></tr><tr><td>Parapetasia femorata</td><td>0.86</td><td>0.00</td><td>0.00</td><td>0.86</td></tr><tr><td>Gemeneta terrea</td><td>0.64</td><td>0.00</td><td>0.00</td><td>0.64</td></tr><tr><td>Gemeneta opilionoides</td><td>0.43</td><td>0.00</td><td>0.00</td><td>0.43</td></tr><tr><td>Apoboleus degener</td><td>0.21</td><td>0.00</td><td>0.21</td><td>0.43</td></tr><tr><td>Cyphocerastis hopei</td><td>0.21</td><td>0.00</td><td>0.00</td><td>0.21</td></tr><tr><td>Taphronota ferruginea</td><td>0.21</td><td>0.00</td><td>0.00</td><td>0.21</td></tr><tr><td><strong>Total</strong></td><td><strong>82.35</strong></td><td><strong>4.53</strong></td><td><strong>13.11</strong></td><td><strong>100</strong></td></tr><tr><td colspan="5"><strong>B. Fallow land species</strong></td></tr><tr><td>Zonocerus variegatus</td><td>10.11</td><td>1.90</td><td>4.50</td><td>16.51</td></tr><tr><td>Catantops sylvestris</td><td>6.27</td><td>2.35</td><td>3.51</td><td>12.13</td></tr><tr><td>Eyprepocnemis plorans</td><td>6.12</td><td>1.03</td><td>1.54</td><td>8.69</td></tr><tr><td>Chirista compta</td><td>4.73</td><td>2.19</td><td>1.42</td><td>8.34</td></tr><tr><td>Odontomelus kamerunensis</td><td>4.15</td><td>0.64</td><td>2.41</td><td>7.20</td></tr><tr><td>Eucoptacra anguliflava</td><td>3.70</td><td>0.45</td><td>0.96</td><td>5.11</td></tr><tr><td>Parapropacris notatus</td><td>3.67</td><td>0.61</td><td>1.32</td><td>5.60</td></tr><tr><td>Serpusia opacula</td><td>3.54</td><td>0.45</td><td>1.48</td><td>5.47</td></tr><tr><td>Atractomorpha acutipennis</td><td>3.22</td><td>0.06</td><td>1.35</td><td>4.63</td></tr><tr><td>Heteropternis thoracica</td><td>1.64</td><td>0.58</td><td>0.38</td><td>2.60</td></tr><tr><td>Oxycatantops spissus</td><td>1.61</td><td>0.00</td><td>0.45</td><td>2.10</td></tr><tr><td>Roduniella insipida</td><td>1.42</td><td>0.00</td><td>0.00</td><td>1.42</td></tr><tr><td>Coryphosima stenoptera</td><td>1.38</td><td>0.10</td><td>0.32</td><td>1.80</td></tr><tr><td>Epistaurus succineus</td><td>1.35</td><td>0.03</td><td>0.19</td><td>1.57</td></tr><tr><td>Cyphocerastis hopei</td><td>1.02</td><td>0.03</td><td>0.67</td><td>1.72</td></tr><tr><td>All other species (23)</td><td>10.00</td><td>0.98</td><td>4.11</td><td>15.10</td></tr><tr><td><strong>Total</strong></td><td><strong>63.92</strong></td><td><strong>11.42</strong></td><td><strong>24.65</strong></td><td><strong>100</strong></td></tr></tbody></table>

Note: A. Forest species and B. fallow land species.

<figure><img src="image_6.png" /><figcaption>FIGURE 5: Continued.</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>FIGURE 5: Distribution and average relative abundance of species by sampling methods. (a) Relative abundance distribution in forest, (b) relative abundance distribution in fallow land, (c) average relative abundance in forest, (d) average relative abundance in fallow land. Note: Results of Chi² tests for pairwise comparisons are indicated as a, b, and c. Pitfall t. = pitfall trap and Open q. = open quadrat.</figcaption></figure>

locusts, crickets, and katydids) in Madagascar [73], and to sample grasshopper assemblages in the littoral region of Cameroon [74]. Similarly, our study in the rainforests of Cameroon confirmed that sweep net sampling captured the most abundant and diverse grasshopper communities in both forest and fallow ecosystems. However, alternative methods such as box quadrat sampling have also demonstrated high efficiency. Fartmann et al. [30] reported that box quadrats allow for rapid and precise assessments of Orthoptera community composition, as they are less dependent on favorable weather conditions and vegetation structure compared to other insect survey techniques. The same authors made several methodological recommendations: For comparing Orthoptera abundance and community composition between habitats, they suggest using 2-m² quadrats with a height of 0.8 m and a minimum sampling area of 20 m² per plot. For long-term monitoring or when targeting low-density species, a sampling area of 30 m² with 15 replicates is recommended. For the survey of small-bodied species and early instar nymphs, smaller box quadrats and sampling areas of less than 20 m² per plot are advised. A decade before, Badenhausser [75] highlighted that a 1-m² quadrat sampling offers robust estimates of grasshopper densities, particularly when accounting for temperature during sampling operations in open landscapes such as intensive agricultural areas and meadows in the Poitou-Charentes region of France. Furthermore, she proposes sampling plans based on count data to estimate grasshopper densities per square meter. The quadrat method proves more effective in ecological zones with high population densities (> 2 adults per m²) of grasshoppers [24, 26, 30]. In contrast, our study revealed low grasshopper abundance in both forest and fallow land areas. Wei et al. [2] used sweep netting within 50 m × 50 m sampling plots to evaluate grasshopper diversity in China. The combination of multiple sampling methods has been successfully applied in various regions, including Germany [29] and South Africa [71]. In urban wastelands of Berlin, Eckert et al. [27] used an integrated approach involving a 100-m transect (with a 2-m buffer on each side), combining

acoustic, visual, and sweep net sampling to assess grasshopper communities. Such multimethod sampling has proven particularly effective for collecting and monitoring grasshopper biodiversity in African rainforest ecosystems, where varied ecological zones and high rates of deforestation complicate biodiversity assessments. Moreover, ongoing human-induced ecological and climatic changes have contributed to the decline—and in some cases, local extinction—of species that were once widespread [76]. In this context, combining complementary sampling techniques enhances detection accuracy and provides a more complete representation of grasshopper assemblages in ecologically threatened environments. Our findings support this approach: 63.92% of the specimens collected in fallow lands were sampled using sweep netting, while the remaining 36.08% were obtained through open quadrats and pitfall traps. Observations during the study revealed that grasshopper movement strategies involved flying or hopping over vegetation and/or the soil surface (litter). Sweep netting proved more effective for capturing species that hop across vegetation, whereas it was less efficient for flying species and those moving primarily along the litter layer. In contrast, pitfall traps and quadrats were more successful in sampling individuals active on the ground or within very short vegetation, but these methods introduced a high bias against flying species. These findings underscore the necessity of combining multiple sampling techniques to ensure a more accurate and comprehensive assessment of grasshopper communities, especially in habitats where insect population densities are low.

## 5. Conclusion

Our study confirms that, as recognized in other part of the world, sweep net sampling is the more effective method for estimating grasshopper assemblages in the rainforests of Central Africa. While open quadrats and pitfall traps did not significantly increase species richness, they substantially contributed to higher estimates of species abundance and diversity, particularly in fallow land ecosystems. Sweep
netting is especially efficient for capturing winged individuals in short vegetation, whereas quadrats and pitfall traps, deployed at the ground level, are better suited for collecting specimens associated with the undergrowth and forest litter—such as *Mazaea granulosa* and *Serpusia opacula*. Therefore, to overcome the limitations of sweep netting and obtain a more complete assessment of grasshopper

diversity in African rainforests, researchers are encouraged to adopt an integrated sampling strategy that combines multiple complementary methods.

## Appendix A

<table><caption>TABLE A1: Absolute abundances of grasshopper species by sampling methods and ecological zones.</caption><thead><tr><th rowspan="2">Taxa</th><th colspan="2">Net</th><th colspan="2">Pitfall trap</th><th colspan="2">Open quadrat</th><th rowspan="2">Total</th></tr><tr><th>Forest</th><th>Fallow land</th><th>Forest</th><th>Fallow land</th><th>Forest</th><th>Fallow land</th></tr></thead><tbody><tr><td>Acrididae MacLeay, 1821</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Acridinae MacLeay, 1821</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Acrida turrita (Linnaeus, 1758)</td><td>0</td><td>3</td><td>0</td><td>1</td><td>0</td><td>2</td><td>6</td></tr><tr><td>Chirista compta (Walker, 1870)</td><td>0</td><td>147</td><td>0</td><td>68</td><td>0</td><td>44</td><td>259</td></tr><tr><td>Coryphosima stenoptera (Schaum, 1853)</td><td>0</td><td>43</td><td>0</td><td>3</td><td>0</td><td>10</td><td>56</td></tr><tr><td>Gymnobothrus temporalis (Stål, 1876)</td><td>0</td><td>23</td><td>0</td><td>12</td><td>0</td><td>6</td><td>41</td></tr><tr><td>Holopercna gerstaeckeri (Bolivar, 1890)</td><td>24</td><td>18</td><td>0</td><td>0</td><td>2</td><td>11</td><td>55</td></tr><tr><td>Odontomelus kamerunensis Ramme, 1929</td><td>0</td><td>129</td><td>0</td><td>20</td><td>0</td><td>75</td><td>224</td></tr><tr><td>Roduniella insipida (Karsch, 1896)</td><td>0</td><td>44</td><td>0</td><td>0</td><td>0</td><td>0</td><td>44</td></tr><tr><td>Catantopinae Brunner von Wattenwyl, 1893</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Abisares viridipennis (Burmeister, 1838)</td><td>0</td><td>9</td><td>0</td><td>2</td><td>0</td><td>3</td><td>14</td></tr><tr><td>Apoboleus degener Karsch, 1891</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>0</td><td>2</td></tr><tr><td>Catantops sylvestris Jago, 1984</td><td>0</td><td>195</td><td>0</td><td>73</td><td>0</td><td>109</td><td>377</td></tr><tr><td>Phaeocatantops signatus (Karsch, 1891)</td><td>0</td><td>20</td><td>0</td><td>2</td><td>0</td><td>12</td><td>34</td></tr><tr><td>Exopropacris rheni (Sjöstedt, 1923)</td><td>0</td><td>15</td><td>0</td><td>2</td><td>0</td><td>6</td><td>23</td></tr><tr><td>Eupropacris coeruleus (Drury, 1773)</td><td>0</td><td>24</td><td>0</td><td>2</td><td>0</td><td>19</td><td>45</td></tr><tr><td>Gemeneta opilionoides (Bolivar, 1905)</td><td>2</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>2</td></tr><tr><td>Gemeneta terrea Karsch, 1892</td><td>3</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>3</td></tr><tr><td>Mazaea granulosa Stål, 1876</td><td>291</td><td>0</td><td>19</td><td>0</td><td>47</td><td>0</td><td>357</td></tr><tr><td>Oxycatantops spissus (Walker, 1870)</td><td>0</td><td>50</td><td>0</td><td>0</td><td>0</td><td>14</td><td>64</td></tr><tr><td>Parapropacris notatus (Karsch, 1891)</td><td>0</td><td>114</td><td>0</td><td>19</td><td>0</td><td>41</td><td>174</td></tr><tr><td>Pteropera carnapi Ramme, 1929</td><td>5</td><td>27</td><td>0</td><td>1</td><td>0</td><td>17</td><td>50</td></tr><tr><td>Pteropera descampsi Donskoff, 1981</td><td>0</td><td>14</td><td>0</td><td>0</td><td>0</td><td>9</td><td>23</td></tr><tr><td>Serpusia opacula Karsch, 1891</td><td>29</td><td>110</td><td>2</td><td>14</td><td>7</td><td>46</td><td>208</td></tr><tr><td>Stenocrobylus festivus Karsch, 1891</td><td>0</td><td>4</td><td>0</td><td>0</td><td>0</td><td>3</td><td>7</td></tr><tr><td>Coptacrinae Brunner von Wattenwyl, 1893</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Cyphocerastis tristis Karsch, 1891</td><td>0</td><td>14</td><td>0</td><td>0</td><td>0</td><td>0</td><td>14</td></tr><tr><td>Cyphocerastis hopei Bruner, 1920</td><td>1</td><td>32</td><td>0</td><td>1</td><td>0</td><td>21</td><td>55</td></tr><tr><td>Cyphocerastis laeta Karsch, 1891</td><td>0</td><td>3</td><td>0</td><td>0</td><td>0</td><td>2</td><td>5</td></tr><tr><td>Epistaurus succineus (Krauss, 1877)</td><td>0</td><td>42</td><td>0</td><td>1</td><td>0</td><td>6</td><td>49</td></tr><tr><td>Eucoptacra anguliflava (Karsch, 1893)</td><td>0</td><td>115</td><td>0</td><td>14</td><td>0</td><td>30</td><td>159</td></tr><tr><td>Cyrtacanthacridinae Kirby, 1910</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Acanthacris ruficornis (Fabricius, 1787)</td><td>0</td><td>14</td><td>0</td><td>0</td><td>0</td><td>13</td><td>27</td></tr><tr><td>Eyprepocnemidinae Brunner von Wattenwyl, 1893</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Eyprepocnemis ibandana (Charpentier, 1825)</td><td>0</td><td>190</td><td>0</td><td>32</td><td>0</td><td>48</td><td>270</td></tr><tr><td>Heteracris guineensis (Krauss, 1890)</td><td>0</td><td>14</td><td>0</td><td>5</td><td>0</td><td>5</td><td>24</td></tr><tr><td>Spathosterninae Rehn, 1957</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Spathosternum pygmaeum Karsch, 1893</td><td>0</td><td>25</td><td>0</td><td>0</td><td>0</td><td>1</td><td>26</td></tr><tr><td>Oedipodinae Walker, 1871</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Heteropternis thoracica (Walker, 1870)</td><td>0</td><td>51</td><td>0</td><td>18</td><td>0</td><td>12</td><td>81</td></tr><tr><td>Morphacris fasciata (Thunberg, 1815)</td><td>0</td><td>3</td><td>0</td><td>0</td><td>0</td><td>1</td><td>4</td></tr><tr><td>Trilophidia conturbata (Walker, 1870)</td><td>0</td><td>8</td><td>0</td><td>1</td><td>0</td><td>0</td><td>9</td></tr><tr><td>Oxyinae Brunner von Wattenwyl, 1893</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Digentia fasciata Ramme, 1929</td><td>8</td><td>1</td><td>0</td><td>0</td><td>3</td><td>0</td><td>12</td></tr><tr><td>Oxya hyla Serville, 1831</td><td>0</td><td>1</td><td>0</td><td>0</td><td>0</td><td>1</td><td>2</td></tr><tr><td>Pterotiltus erythocerus Rowell &amp; Oumarou-Ngoute, 2024</td><td>14</td><td>0</td><td>0</td><td>0</td><td>1</td><td>1</td><td>16</td></tr></tbody></table>
<table><caption>TABLE A1: Continued.</caption><thead><tr><th rowspan="2">Taxa</th><th colspan="2">Net</th><th colspan="2">Pitfall trap</th><th colspan="2">Open quadrat</th><th rowspan="2">Total</th></tr><tr><th>Forest</th><th>Fallow land</th><th>Forest</th><th>Fallow land</th><th>Forest</th><th>Fallow land</th></tr></thead><tbody><tr><td>Pyrgomorphidae Brunner von Wattenwyl, 1874</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Pyrgomorphinae Brunner von Wattenwyl, 1874</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Atractomorpha acutipennis (Guérin-Méneville, 1844)</td><td>0</td><td>100</td><td>0</td><td>2</td><td>0</td><td>42</td><td>144</td></tr><tr><td>Parapetasia femorata Bolivar, 1884</td><td>4</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>4</td></tr><tr><td>Pyrgomorpha vignaudii (Guérin-Méneville, 1847)</td><td>0</td><td>23</td><td>0</td><td>3</td><td>0</td><td>13</td><td>39</td></tr><tr><td>Taphronota calliparea (Schaum, 1853)</td><td>0</td><td>21</td><td>0</td><td>0</td><td>0</td><td>0</td><td>21</td></tr><tr><td>Taphronota ferruginea (Fabricius, 1781)</td><td>1</td><td>27</td><td>0</td><td>0</td><td>0</td><td>3</td><td>31</td></tr><tr><td>Zonocerus variegatus (Linnaeus, 1758)</td><td>0</td><td>314</td><td>0</td><td>59</td><td>0</td><td>140</td><td>513</td></tr><tr><td>Total</td><td>383</td><td>1986</td><td>21</td><td>355</td><td>61</td><td>766</td><td>3572</td></tr></tbody></table>

## Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

## Conflicts of Interest

The authors declare no conflicts of interest.

## Author Contributions

Charly Oumarou Ngoute: conceptualization, methodology, funding acquisition, project administration, investigation, data curation, formal analysis, writing original draft, and writing and review-editing. Philène C. A. Um Nyobe: conceptualization, methodology, investigation, and writing and review-editing. Sévilor Kekeunou: conceptualization, methodology, writing and review-editing, and supervision. Michel Lecoq: conceptualization, methodology, writing and review-editing, and supervision.

## Funding

This study was supported by Rufford Foundation, 19665-1 and by special research funding from the Ministry of Higher Education of Cameroon.

## Acknowledgments

This study was supported by a Rufford Small Grant (Application ID: 19665-1) and by special research funding from the Ministry of Higher Education of Cameroon. We extend our sincere gratitude to Dr. Nganso of the National Herbarium of Cameroon for his assistance in plant species identification. We also pay tribute to late Prof. Charles F. Bilong Bilong, whose guidance and contributions were instrumental to the success of this work.

## Supporting Information

Additional supporting information can be found online in the Supporting Information section. (Supporting Information)

Plants species composition in the studied localities. Table S1: In forests; Table S2: In fallow lands.

## References

[1] J. Y. Humbert, S. Delley, and R. Arlettaz, "Grassland Intensification Dramatically Impacts Grasshoppers: Experimental Evidence for Direct and Indirect Effects of Fertilisation and Irrigation," *Agriculture, Ecosystems & Environment* 314 (2021): 107412, https://doi.org/10.1016/j.agee.2021.107412.

[2] S. Wei, X. Liu, M. R. McNeill, et al., "Identification of Spatial Distribution and Drivers for Grasshopper Populations Based on Geographic Detectors," *Ecological Indicators* 154 (2023): 110500, https://doi.org/10.1016/j.ecolind.2023.110500.

[3] M. Brandl, R. I. Hussain, B. Maas, D. Rabl, B. Pachinger, et al., "Improving Insect Conservation Values of agri-environment Schemes Through Diversified Seed Mixtures," *Biological Conservation* 269 (2022): 109530, https://doi.org/10.1016/j.biocon.2022.109530.

[4] T. Fartmann, B. Kramer, F. Stelzner, and D. Poniatowski, "Orthoptera as Ecological Indicators for Succession in Steppe Grassland," *Ecological Indicators* 20 (2012): 337-344, https://doi.org/10.1016/j.ecolind.2012.03.002.

[5] R. Walcher, R. I. Hussain, L. Sachslehner, J. G. Zaller, A. Arnberger, and T. Frank, "Assessing Grasshopper Communities in Mountainous Meadows -A Comparison of a visual-acoustic and a Novel, Purely Acoustic Soundscape Method," *Entomologia Experimentalis et Applicata* 170 (2022): 895-901, https://doi.org/10.1111/eea.13209.

[6] Y. Li, Q. Liu, X. Zhang, et al., "Effects of Environmental Factors on the Diversity of Grasshopper Communities Along Altitude Gradients in Xizang, China," *Insects* 15 (2024): 671, https://doi.org/10.3390/insects15090671.

[7] R. van Klink, D. E. Bowler, K. B. Gongalsky, M. Shen, S. R. Swengel, and J. M. Chase, "Disproportionate Declines of Formerly Abundant Species Underlie Insect Loss," *Nature* 628 (2024): 359-364, https://doi.org/10.1038/s41586-023-06861-4.

[8] T. R. Bishop, M. P. Robertson, B. J. V. Rensburg, and C. L. Parr, "Elevation-Diversity Patterns Through Space and Time: Ant Communities of the Maloti-Drakensberg Mountains of Southern Africa," *Journal of Biogeography* 41 (2014): 2256-2268, https://doi.org/10.1111/jbi.12368.

[9] R. Tito, H. L. Vasconcelos, and K. J. Feeley, "Mountain Ecosystems as Natural Laboratories for Climate Change Experiments," *Frontiers in Forests and Global Change* 3 (2020): 38, https://doi.org/10.3389/ffgc.2020.00038.

[10] X. Song, M. Cao, J. Li, et al., "Different Environmental Factors Drive Tree Species Diversity Along Elevation Gradients in Three Climatic Zones in Yunnan, southern China," *Plant Diversity* 43 (2021): 433-443, https://doi.org/10.1016/j.pld.2021.04.006.
[11] V. H. Resh and E. P. McElravy, "Contemporary Quantitative Approaches to Biomonitoring Using Benthic Macro-invertebrates," in *Freshwater Biomonitoring and Benthic Macroinvertebrates*, ed. D. M. Rosenberg and V. H. Resh (London, UK: Chapman & Hall, 1993), 59-194.

[12] J. L. Carter and V. H. Resh, "After Site Selection and Before Data Analysis: Sampling, Sorting, and Laboratory Procedures Used in Stream Benthic Macroinvertebrate Monitoring Programs by USA State Agencies," *Journal of the North American Benthological Society* 20 (2001): 658-682, https://doi.org/10.2307/1468095.

[13] S. A. Bonar and W. A. Hubert, "Standard Sampling of Inland Fish: Benefits, Challenges, and a Call for Action," *Fisheries* 27 (2002): 10-16.

[14] Y. Cao, C. P. Hawkins, and A. W. Storey, "A Method for Measuring the Comparability of Different Sampling Methods Used in Biological Surveys: Implications for Data Integration and Synthesis," *Freshwater Biology* 50 (2005): 1105-1115, https://doi.org/10.1111/j.1365-2427.2005.01377.x.

[15] H. Tahderdoost, "Sampling Methods in Research Methodology; How to Choose a Sampling Technique for Research," *International Journal of Academic Research in Management* 5 (2016): 18-27.

[16] I. Etikan and K. Bala, "Sampling and Sampling Methods," *Biometrics & Biostatistics International Journal* 5 (2017): 215-217.

[17] E. G. McDermott and T. J. Lysyk, "Sampling Considerations for Adult and Immature Culicoides (Diptera: Ceratopogonidae)," *Journal of Insect Science* 20 (2020): 1-11, https://doi.org/10.1093/jisesa/ieaa025.

[18] Y. Yan, H. Ma, and Z. Li, "An Improved Grasshopper Optimization Algorithm for Global Optimization," *Chinese Journal of Electronics* 30 (2021): 451-459, https://doi.org/10.1049/cje.2021.03.008.

[19] O. W. Richards, "The Study of the Number of the Red Locust (*Nomadacris septemfasciata* Serv.)," *Anti-Locust Bulletin* 15 (1953): 1-31.

[20] O. W. Richards, N. A. Waloff, and N. Waloff, "Studies on the Biology and Population Dynamics of British Grasshoppers," *Anti-Locust Bulletin* 17 (1954): 1-182.

[21] C. Clark, C. Ashall, Z. Waloff, and L. Chinnick, "Field Studies on the Australian Plague Locust (*Chortoicetes terminifera* Walk.) in the "Channel Country" of Queensland," *Anti-Locust Bulletin* 44 (1969): 1-101.

[22] T. H. Holmes and R. A. Arnold, "Generalized Generation Population Size Estimation of Endangered Insects via Parsonious, Flexible Integration of Transect Counts with mark-release-recapture Data," *Annals of the Entomological Society of America* 108 (2015): 160-171, https://doi.org/10.1093/aesa/sau007.

[23] K. I. Perry, K. F. Wallin, J. W. Wenzel, and D. A. Herms, "Characterizing Movement of Ground-Dwelling Arthropods with a Novel Mark-Capture Method Using Fluorescent Powder," *Journal of Insect Behavior* 30 (2017): 32-47, https://doi.org/10.1007/s10905-017-9598-0.

[24] T. Gardiner, J. Hill, and D. Chesmore, "Review of the Methods Frequently Used to Estimate the Abundance of Orthoptera in Grassland Ecosystems," *Journal of Insect Conservation* 9 (2005): 151-173, https://doi.org/10.1007/s10841-005-2854-1.

[25] C. Turlure, G. Pe'er, M. Baguette, and N. Schtickzelle, "A Simplified mark-release-recapture Protocol to Improve the Cost Effectiveness of Repeated Population Size Quantification," *Methods in Ecology and Evolution* 9 (2018): 645-656, https://doi.org/10.1111/2041-210X.12900.

[26] T. Gardiner and J. Hill, "A Comparison of Three Sampling Techniques Used to Estimate the Population Density and Assemblage Diversity of Orthoptera," *Journal of Orthoptera Research* 15 (2006): 45-51, https://doi.org/10.1665/1082-6467(2006)15[45:acotst]2.0.co;2.

[27] S. Eckert, M. Moller, and S. Buchholz, "Grasshopper Diversity of Urban Wastelands is Primarily Boosted by Habitat Factors," *Insect Conservation and Diversity* 10 (2017): 248-257, https://doi.org/10.1111/icad.12221.

[28] F. Sengendo, S. Subramanian, M. Kidoido, M. Chemurot, C. Tanga, and J. P. Egonyu, "Cost-Benefit Analysis of Improved Light Trap for Harvesting the Edible Grasshopper, Ruspolia differens (Orthoptera: Tettigoniidae): Evidence from Uganda," *International Journal of Tropical Insect Science* 41 (2021): 1913-1921, https://doi.org/10.1007/s42690-021-00505-8.

[29] M. Streitberger, G. Stuhldreher, T. Fartmann, et al., "The German Insect Monitoring Scheme: Establishment of a Nationwide long-term Recording of Arthropods," *Basic and Applied Ecology* 80 (2024): 81-91, https://doi.org/10.1016/j.baae.2024.08.004.

[30] T. Fartmann, F. M. Freienstein, F. Helbing, G. Scherer, and D. Poniatowski, "A Box Quadrat for Standardised Sampling of Orthoptera in Open Habitats: Design, Handling, Applications and Baseline Data," *Global Ecology and Conservation* 55 (2024): e03217, https://doi.org/10.1016/j.gecco.2024.e03217.

[31] M. Lecoq, "Biologie Et Dynamique D'Un Peuplement Acrialien De Zone Soudanienne En Afrique De L'Ouest (Orthoptera, Acrididae) [Biology and Population Dynamics of Grasshoppers (Orthoptera, Acrididae) in the Sudanian Zone of West Africa]," *Annales de la Société Entomologique de France* 14, no. 4 (1978): 603-681, https://doi.org/10.1080/21686351.1978.12278711.

[32] D. P. Larson, K. M. O'Neill, and W. P. Kemp, "Evaluation of the Accuracy of Sweep Sampling in Determining Grasshopper (Orthoptera: Acrididae) Community Composition," *Journal of Agricultural and Urban Entomology* 16 (1999): 207-214.

[33] Y. Mariottini, M. L. De Wysiecki, R. Cepeda, et al., "Grasshopper (Orthoptera: Acridoidea) Diversity in the Pampas Region of Argentina: Status as Revealed by long-term Sampling," *Journal of Insect Conservation* 28 (2024): 1265-1283, https://doi.org/10.1007/s10841-024-00622-y.

[34] S. R. Leather, J. H. Lawton, and G. E. Likens, *Insect Sampling in Forest Ecosystems. Methods in Ecology* (Blackwell Publishing, 2005).

[35] A. C. Wandji, S. Kekeunou, M. Mbadjoun-Nzike, A. Simeu-Noutchoum, and A. Fomena, "Grasshopper (Orthoptera: Acrididea) Assemblages in Forests and Savanna Areas in Center, West and South-West Regions of Cameroon," *Journal of Insect Biodiversity* 12 (2019): 17-32, https://doi.org/10.12976/jib/2019.12.1.3.

[36] C. Oumarou-Ngoute, S. Kekeunou, M. Lecoq, A. R. Nzoko Fiemapong, P. C. A. Um Nyobe, and C. F. Bilong Bilong, "Effect of Anthropogenic Pressure on Grasshopper (Orthoptera: Acridomorpha) Species Diversity in Three Forests in Southern Cameroon," *Journal of Orthoptera Research* 29 (2020): 25-34, https://doi.org/10.3897/jor.29.33373.

[37] P. C. A. Um Nyobe, S. Kekeunou, L. Ma, T. Robillard, A. Simeu-Noutchom, and C. F. Bilong-Bilong, "Description and Bioecology of Two New Species of the Genus *Cryncus* (Orthoptera, Gryllidae, Gryllinae) from Cameroon with a Key and Distribution Map of all African Species," *Zootaxa* 4908 (2021): 473-488.
[38] P. C. A. Um Nyobe, T. Robillard, S. Kekeunou, L. Ma, M. Mbadjoun-Nzike, and C. F. Bilong-Bilong, "Description of Two New Species of Turanogryllini Crickets (Orthoptera, Gryllidae, Gryllinae) from Cameroon, with Identification Keys for African Species," *Journal of Orthoptera Research* 31 (2022): 83–89, https://doi.org/10.3897/jor.31.373389.

[39] P. C. A. Um Nyobe, C. Oumarou-Ngoute, A. R. Nzoko-Fiemapong, T. Robillard, L. Ma, and S. Kekeunou, "Description of One New Species of the Genus *Gymnogryllus* (Orthoptera, Gryllidae, Gryllinae) from Cameroon with a Key for African Species," *Zootaxa* 5369 (2023): 591–596.

[40] M. Rejou-Mechain, F. Mortier, J. F. Bastin, et al., "Unveiling African Rainforest Composition and Vulnerability to Global Change," *Nature* 593 (2021): 90–94, https://doi.org/10.1038/s41586-021-03483-6.

[41] L. J. T. White, E. B. Masudi, J. D. Ndongo, et al., "Congo Basin Rainforest - Invest US$150 Million in Science," *Nature* 598 (2021): 411–414, https://doi.org/10.1038/d41586-021-02818-7.

[42] J. A. Zwets, E. H. M. Sterck, P. A. Verweij, et al., "FSC-Certified Forest Management Benefits Large Mammals Compared to non-FSC," *Nature* 628 (2024): 563–568, https://doi.org/10.1038/s41586-024-07257-8.

[43] M. Tsalefac, F. Hiol-Hiol, G. Mahé, et al., "Climate of Central Africa: past, Present and Future," in *The Forests of the Congo Basin - Forests and Climate Change*, ed. C. De-Wasseige, M. Tadoum, R. Eba'a Atyi, and C. Doumenge (Belgium: Weyrich, Neufchâteau, 2015).

[44] E. Westphal, J. Embrechts, P. Mbouemboue, J. M. C. Westphal-Stevels, and Mouzong-Boyomo, "L'Agri-culture Autochtone Au Cameroun: Les Techniques Cultur-ales, Les Séquences De Culture, Les Plantes Alimentaires Et Leur Consommation," in *Miscellaneous Papers 20/Land-bouwhogescool* (Veenman & Zonen, 1981).

[45] J. J. Gockowski, "Quelques Données De L'Enquête Agricole Dans Les Villages De Recherche," *Programme EPHTA en collaboration avec l'IRAD/ASB. Yaoundé: IITA-Yaoundé* (1996).

[46] C. Oumarou-Ngoute, S. Kekeunou, and C. F. Bilong-Bilong, "Grasshopper (Orthoptera: Acridomorpha) Diversity in Re-sponse to fallow-land Use in Southern Cameroon with Recommendations for Land Management," *Journal of Insect Science* 23 (2023): 5, https://doi.org/10.1093/jisesa/iead011.

[47] V. M. Dirsh, "Revision of the Genus *Eyprepocnemis* Fieber, 1853 (Orthoptera, Acrididae)," *Proceedings of the Royal Entomological Society* 27 (1958): 33–45.

[48] V. M. Dirsh, *The African Genera of Acridoidea* (New York and London: Cambridge University Press, 1965).

[49] V. M. Dirsh, "Acridoidea of the Congo (Orthoptera)," *Annales du Musée royal d'Afrique central (série Sciences zoologiques)* 182 (1970): 1–605.

[50] M. Donskoff, "Les Acridiens De la Foret Africaine I- Révision Du Genre *Pteropera* Karsch, 1891 (Orthoptera, Acrididae)," *Annales de la Société Entomologique de France* 17 (1991): 33–88.

[51] J. P. Grunshaw, "A Revision of the Grasshoppers' Genus *Heteracris* (Orthoptera: Acrididae: Eyprepocnemidinae)," *Bulletin Series* (Kent, UK: Natural Resources Institute, Chatham Maritime, 1991).

[52] D. Hollis, "A Review of the Subfamily Oxyinae (Orthoptera: Acridoidea)," *Bulletin of the British Museum (Natural History) Entomology* 31 (1975): 189–234.

[53] N. D. Jago, "The Alate Genera of East African Catantopinae (Orthoptera, Acridoidea) Including Revision of the Genus

Catantops Schaum," *Trans. Entomological Society of America* 110 (1984): 295–387.

[54] N. D. Jago, "Revision of the African Grasshopper Genus *Oxycatantops* Dirsh & Uvarov 1953 (Orthoptera, Acridoidea, Acrididae, Catantopinae)," *Tropical Zoology* 2 (1989): 207–234.

[55] N. D. Jago, "Odontomelus I. Bolivar 1890 (orthoptera Acridoidea Acrididae Acridinae): Savanna-Woodland Grasshoppers with a Major Radiation of Flightless Species in Eastern Africa," *Tropical Zoology* 7 (1994): 367–450.

[56] N. D. Jago, "Review of the African Genera *Catantops* Schaum 1853, *Hadrolecocatantops* jago 1984, and *Vitticatantops* Sjostedt 1931 (Orthoptera, Acrididae, Catantopinae)," *Journal of Orthoptera Research* 3 (1994): 69–85, https://doi.org/10.2307/3503411.

[57] F. Karsch, "Verzeichnis Der Von Herrn Dr. Paul Preuss in Kamerun Erbeuteten Acridoideen," *Berliner Entomologische Zeitschrift* 36 (1891): 175–196.

[58] D. K. M. E. Kevan, "A Revised Synopsis of the Genus *Atractomorpha* Saussure, 1862 (Orthoptera: Pyrgomorphidae) with an Account of the African aberrans-groups," *Zoological Journal of the Linnean Society* 48 (1969): 141–198, https://doi.org/10.1111/j.1096-3642.1969.tb00710.x.

[59] D. K. M. E. Kevan, "A Revision of the Genus *Taphronota* Stal, 1873 (Orthoptera, Acrididae, Pyrgomorphidae)," *Publicacoes Culturals da Companhia de Diamantes Angola* 88 (1974): 79–149.

[60] W. Ramme, "Afrikanische Acrididae. Revisionen Und Beschreibungen Wenig Bekannter Und Neuer Gattungen Und Arten," *Mitteilungen aus dem Zoologischen Museum in Berlin* 15 (1929): 247–492.

[61] C. H. F. Rowell, C. Hemp, and A. W. Harvey, "Jago's Grasshoppers of East and North East Africa," *Pneumoridae, Pyrgomorphidae, Lentulidae, Pamphagidae, and Dericorythidae*, 1 (San Francisco, USA: Blurb Publishers, 2015).

[62] C. H. F. Rowell and C. Hemp, "Jago's Grasshoppers of East and North East Africa," *Acrididae: Teratodinae, Hemi-acridinae, Spathosterninae, Tropidolinae, Calliptaminae, Oxyinae, Coptacrinae and Eyprepocnemidinae*. Blurb Publishers 2 (San Francisco, USA, 2017).

[63] C. H. F. Rowell and C. Hemp, in *Jago's Grasshoppers of East and North East Africa*, 3 (Blurb Publishers, 2018).

[64] R. Dajoz, *Précis D'Écologie* (Paris: Bordas, 1982).

[65] E. Marcon, "Mesures De La Biodiversité," *Kourou: UMR Ecologie des forêts de Guyane* (2018): https://agroparistech.hal.science/cel-01205813v5.

[66] R. K. Colwell, "Estimates: Statistical Estimation of Species Richness and Shared Species from Samples," (2013), http://purl.oclc.org/estimates.

[67] Ø Hammer, *PAST: Paleontological Statistics, Version 4.17* (USA: Natural History Museum, University of Oslo, 2024).

[68] K. Hutcheson, "A Test for Comparing Diversities Based on the Shannon Formula," *Journal of Theoretical Biology* 29 (1970): 151–154.

[69] J. Guo, W. Huang, Y. Dong, et al., "Spatiotemporal Monitoring of Grasshopper Habitats Using multi-source Data Combined with Landscape and Spatial Heterogeneity," *International Journal of Applied Earth Observation and Geoinformation* 130 (2024): 103838, https://doi.org/10.1016/j.jag.2024.103838.

[70] V. Noguerales, P. J. Cordero, and J. Ortego, "Testing the Role of Ancient and Contemporary Landscapes on Structuring Genetic Variation in a Specialist Grasshopper,"
*Ecology and Evolution* 7 (2017): 3110–3122, https://doi.org/
10.1002/ece3.2810.

[71] S. Adu-Acheampong, M. J. Samways, T. Landmann, et al., “Endemic Grasshopper Species Distribution in an agro-natural Landscape of the Cape Floristic Region, South Africa,” *Ecological Engineering* 105 (2017): 133–140, https://doi.org/10.1016/j.ecoleng.2017.04.037.

[72] P. K. Kariuki, F. Toroitich, G. Ongamo, J. M. Nduko, E. Owino, and A. King’Ori, “Diversity and Abundance of Grasshopper and Locust Species in Nakuru County, Kenya,” *Asian Journal of Conservation Biology* 8 (2019): 102–109.

[73] J. V. Itterbeeck, I. N. Rakotomalala-Andrianavalona, F. I. Rajemison, et al., “Diversity and Use of Edible Grasshoppers, Locusts, Crickets, and Katydids (Orthoptera) in Madagascar,” *Foods* 8 (2019): 666, https://doi.org/10.3390/foods8120666.

[74] J. A. Yetchom-fondjo, S. Kekeunou, M. Kenne, A. D. Missoup, and X. Sheng-Guan, “Diversity, Abundance and Distribution of Grasshopper Species (Orthoptera: Acrididea) in Three Different Types of Vegetation with Different Levels of Anthropogenic Disturbances in the Littoral Region of Cameroon,” *Journal of Insect Biodiversity* 14 (2020): 16–33, https://doi.org/10.12976/jib/2020.14.1.3.

[75] I. Badenhausser, “Estimation D’Abondance Des Criquets (Orthoptera: Acrididae) Dans Les Écosystèmes Prairiaux,” *Annales de la Société Entomologique de France* 48 (2012): 397–406, https://doi.org/10.1080/00379271.2012.10697787.

[76] L. S. Dey, M. V. P. Simões, O. Hawlitschek, et al., “Analysis of Geographic Centrality and Genetic Diversity in the Declining Grasshopper Species *Bryodemella tuberculata* (Orthoptera: Oedipodinae),” *Biodiversity & Conservation* 30 (2021): 2773–2796, https://doi.org/10.1007/s10531-021-02221-8.

[77] A. Verhegghen, C. Mayaux, W. de, and P. Defourny, “Mapping Congo Basin Vegetation Types from 300 M and 1 Km multi-sensor Time Series for Carbon Stocks and Forest Areas Estimation,” *Biogeosciences* 9 (2012): 5061–5079, https://doi.org/10.5194/bg-9-5061-2012.