IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Research article
erd

Assessment of Insect Damage and Growth Performance ofDipterocarps Planted at Rainforestation Demonstration Farmat VSU, Baybay City, Leyte
KLEER JEANN G. LONGATANG*
Visayas State University, Baybay City, Philippines
Email: kleerjeann.longatang@vsu.edu.ph

MA. JULIET C. CENIZA
Visayas State University, Baybay City, Philippines

CHRISTOPHER JR. R. GALGO
Visayas State University, Baybay City, Philippines

JIMMY O. POGOSA
Visayas State University, Baybay City, Philippines

DENNIS P. PEQUE
Visayas State University, Baybay City, Philippines

LEONARD PAOLO LONGATANG
Visayas State University, Baybay City, Philippines
Received 30 December 2020

Accepted 16 May 2021(*Corresponding Author)

Abstract Assessment of associated insects and leaf damage caused by insects is essential
concerning decisions to contribute to developing suitable rehabilitation techniques. Few studies
have been done to identify the insect species associated with dipterocarp species and determine
the damage caused by insects and their growth performance. Six species of dipterocarps,
namely: Dipterocarpus alatus (hairy leaf apitong), Hopea philippinensis (gisok-gisok), Shorea
malibato (malibato), Shorea assamica (manggasinoro), Shorea polita (malaanonang), andShorea almon, were studied. This study was conducted to determine the insect-associated faunausing the visual and handpicking method of insect collection, leaf damage assessment using theBioleaf app, and the morphological traits (i.e., basal diameter and plant height) on the growth
performance of dipterocarps. There were eight orders of insects associated with thedipterocarps: Coleoptera, Diptera, Hemiptera, Heteroptera, Hymenoptera, Lepidoptera, Odonata,and Orthoptera. There was a significant difference (p ≤ 0.05) in the leaf damage among the six
dipterocarps species after 25 months from planting. Shorea assamica had the highest leaf
damage (8.68% ± 0.09), and Shorea almon had the least leaf damage (2.57% ± 0.09). In termsof basal diameter, the species with the highest significant increment (p ≤ 0.05) was Shorea
polita (2.49 ± 0.67 mm), while Shorea almon had the least growth increment (0.98 ± 0.67 mm)
25 months after planting. Dipterocarpus alatus grows faster for the plant height than otherspecies with a significant increment (p ≤ 0.05) of 32.90 ± 0.19 cm, while Shorea assamica had
the least increment of (4.95 ± 0.19) cm. The study indicated eight orders of insects associatedwith the dipterocarps showing significant damage on the S. assamica. Despite the insect
association, the plants grow significantly with the rapid increase observed on D. alatus.
Keywords dipterocarp, defoliation, insect fauna, leaf damage, bioleafⒸ ISERD

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INTRODUCTION
Herbivorous species, mostly insects, are a significant global biodiversity component, comprising
approximately 25% of all described species. Insect herbivores are among the many biotic factors
known to help maintain forest diversity through selective predation on vulnerable tree species'
seedlings altering forest community composition (Norghauer and Newbery, 2013). Insect herbivores,
directly and indirectly, influence plant community composition by altering the recruitment, mortality,
or individual growth rates of plant species, as supported by Maron and Crone, 2006.
Dipterocarps are known worldwide because of their economic and ecological functions. It has agood timber quality exported to other countries in finished products such as plywood and sawn timber(Corlett and Primack, 2005). According to Langenberger (2005), some species of dipterocarps areindicators for site suitability in local reforestation programs. Moreover, insect herbivores increase tree
seedling recruits (Dyer et al., 2010). Annual rates of leaf damage are higher in tropical forests than intemperate broad-leaved forests (Coley and Barone, 1996). In the natural Dipterocarp forest, insects are
the primary source of damage as leaf feeders, borers, suckers, and gall formation (Appanah, 1998).
Despite the knowledge about the damages caused by the insects' attack, few studies have been
done in the Philippines to identify the insect species associated with Dipterocarpus alatus (hairy leaf
apitong), Hopea philippinensis (gisok-gisok), Shorea malibato (malibato), Shorea assamica(manggasinoro), Shorea polita (malaanonang), Shorea almon and its growth performance. Thesespecies were chosen because of their conservation status according to the Updated National List ofThreatened Philippine Plants and Their Categories by the Department of Environment and Natural
Resources Administrative Order No. 2017-11. Assessing the damage caused by the insect is essential
concerning assisting experts to make better decisions to contribute to efforts of developing suitablerehabilitation techniques and to recommend favorable dipterocarp species that can stand insect
herbivory. Furthermore, the study used a novel approach in assessing leaf damage i.e., using theBioleaf app for the first time on dipterocarps which in the literature has been commonly used inassessing leaf damage on soybean (Machado, 2016)
OBJECTIVES1. To identify the insect species associated with the dipterocarps planted in the dipterocarp germplasm
and;2. To assess the leaf damage of insects and growth performance of dipterocarps planted in thedipterocarp germplasm of VSU, Baybay City, Leyte, Philippines.
METHODOLOGY
Location of the Study Site
The study site was located at the Dipterocarp germplasm of the Terrestrial Ecosystems Division (TED),
Institute of Tropical Ecology and Environmental Management (ITEEM) field laboratory establishednear the Rainforestation Research Training Center (RRTC), Visayas State University-Main Campus,Baybay City, Leyte, Philippines (Fig. 1). It has a total area of approximately 1.80 hectares planted to30 species of dipterocarps. The seedlings were randomly planted with a planting distance of 5 meters x
5 meters, constituting 21 seedlings per species. Six species of dipterocarp trees are randomly selectedamong the species of dipterocarps planted in the germplasm.

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Fig. 1 The study site is located in Visca, Baybay City, Leyte, Philippines.
Assessment of Insect Fauna Associated with Dipterocarps
To identify the insect species inflicting damage on the trees and affected their growth performance,
visual observation and handpicking was used as an insect collection method (Fig. 2). This included
documenting all insects encountered and their damage among the sample plants. Insects observed werephotographed, documented, and were collected by handpicking. They were brought to the laboratory tovalidate and identify the type of damage to the tree species. Insects that were collected were identified
according to Order level. Sampling was done every morning (6:00 to 8:00 a.m.) and afternoon (3:00 to5:00 p.m.). Samples were separately placed in jars with a killing agent and brought to the laboratory forprocessing, identification, and recording. Insects collected from each sample tree were separately kept
for counting and sorting (Fig. 3). The different arthropod species were classified according to thefollowing categories (Wall work, 1976 as cited by Ceniza, 1995). Insects can be considered“accidental” if the species occurs in 1-24 % of samples; “accessory” if the species occurs in 25-49% ofsamples; “constant” if the species occurs in 50-74% of samples; and “absolute” if the species occurs in
75-100% of samples.

Fig. 2 Visual andhandpicking

Fig. 3 Sorting of insects in labeled plastic wares
and vials

Assessment of Leaf Damage Using the Bioleaf App
The study followed the methodology on insect herbivory assessment by Herve et al. 2017, which issuitable for this study. Measures were made on a fixed number of leaves per tree, choosing two facing
opposite branches at the top and two facing opposite branches at the middle, and two facing oppositebranches bottom of the tree crown. Ten leaves were randomly chosen at the top of a branch, ten at theⒸ ISERD24

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middle, and ten leaves at the bottom per tree per species. If there were not enough leaves on the branch,
one could choose another branch at the same height. If there are not enough branches, one can use themain axis. Assessed leaves were different from one assessment to the next because some may fell,
some may have appeared, and damage may have accumulated. Bioleaf foliar analysis was used toestimate the damage (Machado et al., 2016), a professional mobile application to measure foliar
damage caused by insect herbivory, developed by a Brazilian team of researchers released in 2016. It
then estimated the defoliation percentage related to the total area using images captured from thecamera or loaded from the photo gallery. Pictures of the leaf images taken from the field were loaded
into the bioleaf app, automatically reading the injured leaf regions caused by insect herbivory andestimating the total area's defoliation percentage (Fig. 4).

Fig. 4 Process flow for the bioleaf foliar analysis
Growth Performance of Dipterocarp Species
Ten sample plants per species of dipterocarp were measured every three months. The basal diameter(mm) was measured at the base of the stem using a Vernier caliper. The sample plants' base wasmarked with white ink to ensure a permanent measurement point from the present to the following datacollection (Fig. 5). Meanwhile, the plant height (cm) was measured using a meter stick. It was takenfrom the stem's base up to the stem's tip (Fig. 6).

Fig. 5 Measuring the basal diameter

Fig. 6 Measuring the total plant hight

Data Encoding and Statistical Analysis
All data gathered were collated, encoded, and summarized using an electronic spreadsheet editor,
Microsoft Excel 2013. The data were analyzed using the Statistical Package for Social Science (SPSSversion 20). The mean of basal diameter and plant height variability were analyzed using the one-way
analysis of variance (ANOVA). Moreover, in a case where the significant variations at p ≤ 0.05 wereidentified, Tukey and Least Squares Differences (LSD) were carried out to compare means.
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RESULTS AND DISCUSSION
Insect Species Associated with Dipterocarp Species
Table 1 shows the list of insect orders associated with the dipterocarps. It included eight insects,
namely, Coleoptera, Diptera, Hemiptera, Heteroptera, Hymenoptera, Lepidoptera, Odonata Orthoptera.
These groups were composed of chewers and suckers, the major groups causing damage to thedipterocarp species.
Table 1 List of insect order associated with the dipterocarp speciesDipterocarp species

Insect orders with constancy class

Dipterocarpus alatus

Orthoptera-(Ab), Coleoptera- (A), Hemiptera- (A), Lepidoptera (Ab), Odonata (A)Hopea philippinensis

Orthoptera-(C), Coleoptera- (Ac), Hemiptera- (Ac), Lepidoptera (Ab)

Shorea almon

Orthoptera-(A), Coleoptera- (A), Hemiptera- (A), Lepidoptera (Ab)

Shorea assamica

Orthoptera-(Ab), Coleoptera- (Ab), Hemiptera- (Ab), Lepidoptera (Ab), Heteroptera(Ab), Diptera (C), Hymenoptera (Ab), Odonata (Ac)

Shorea malibato

Orthoptera-(C), Coleoptera- (Ac), Hemiptera- (Ac), Lepidoptera (Ab)

Shorea polita

Orthoptera-(C), Coleoptera- (A), Hemiptera- (A), Lepidoptera (Ab)

Note: Accidental 1-24% Ac- Accessory 25-49% C- Constant 50-74% Ab- Absolute 75-100%

Leaf Damage
The leaf damage samples of six dipterocarp species were shown in Fig. 7. The statistical analysis
results showed significant (p ≤ 0.05) differences in the leaf percentage damage among the six
dipterocarps species during the data collection 25 months after planting. Fig. 8 shows the results on theleaf percentage damage of dipterocarp species in the three sampling periods. Shorea assamica had thehighest leaf damage (8.68% ± 0.087), and Shorea almon had the least leaf percentage damage (2.57%± 0.087).

Fig. 7 Leaf damage samples of six dipterocarp
speciesFig. 8 Percentage damage of leaves of six
dipterocarp species
Note: Values in the figure with different letters (a-b)
designation across treatments during datacollection periods are statistically significant at p ≤0.05. N = 10 in total for all treatments per species
per period.

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Basal Diameter and Plant HeightThe different dipterocarp species' growth performance showed increments and variations after a 3month sampling period, 25 months after planting. Increments are used as a measure of performance inour forest stands for a particular period (Assmann, 1970). This was calculated as the difference
between the initial growth of the height and basal diameter of the plant at 22 months and its growth
after 3months and 6 months.The most significant growth increment was the Shorea polita (2.49 mm ±0.67) regarding basal diameter. At the same time, Shorea almon had the least growth increment (0.98 ±0.67). However, it can be seen from the results that regardless of the dipterocarp species, there was anincrease in the growth of the basal diameter between the periods of the first three months and sixmonths (Fig. 9). At least one species in every Dipterocarp genus differed in terms of basal diameter
among other species. There was a significant increase in dipterocarp species for the plant height after
six months of data collection, 28 months after planting (Fig. 10). There is evidence that at least one
species in each Dipterocarp genus differs in plant height among other species. Notably, Dipterocarpus
alatus (32.90 cm ± 0.19) had a considerable increment in plant height, while Shorea assamica (4.95 cm± 0.19) had the least increment, 28 months after planting.

Fig. 9 Basal diameter increment of six
dipterocarp species

Fig. 10 Height increment of six
dipterocarp species

Note: Values in the figure with different letters (a-b)
designation across treatments during data collection
periods are statistically significant at p ≤ 0.05. N =10 in total for all treatments per species per period.

Note: Values in the figure with different
letters (a-b) designation across treatments
during data collection periods are statisticallysignificant at p ≤ 0.05. N = 10 in total for all
treatments per species per period.

CONCLUSION
There are eight orders of insects associated with dipterocarps: Coleoptera, Diptera, Hemiptera,Heteroptera, Hymenoptera, Lepidoptera, Odonata, and Orthoptera, showing significant damage on theS. assamica. There was a significant difference (p ≤ 0.05) in the leaf damage among the six
dipterocarps species during the data collection 25 months after planting. Shorea assamica had the mostsignificant leaf damage, and Shorea almon had the least leaf damage. The different dipterocarp species'
growth performance showed significant increments (p ≤ 0.05) and variations after a 3-month sampling
period, 25 months after planting. In terms of basal diameter, the species with the most significant
growth increment was Shorea polita. At the same time, Shorea almon had the least growth increment.
Dipterocarpus alatus grow significantly (p ≤ 0.05), which had the largest increment for the plant height
despite the insect association, while Shorea assamica had the least increment. The assessment ofassociated insects is more relevant in assessing the damage of insects. Thus, it is suggested that afurther detailed study and analysis on the family and species level of other groups should be conductedto enhance the recent findings.

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ACKNOWLEDGEMENT
This study was supported by the Environmental Leadership and Training Initiative (ELTI) and Visayas
State University (VSU).
REFERENCES
Appanah, S. and Turnbull, J.M. 1998. A review of dipterocarps: Taxonomy. Ecology and Silviculture.
Assman, E. 1970. Principles of forest yield study: Studies in the organic production, structure, increment andyield of forest stands. 207-433.
Ceniza, M.J. 1995. Arthropod abundance and diversity in different ecosystems of Mount Pangasugan, Baybay,Leyte, Philippines with special reference to the Coleoptera and Hymenoptera. PLITS, 13 (3), 65-71.
Coley, P.D. and Barone, J.A. 1996. Herbivory and plant defenses in tropical forests. Annual Review of Ecologyand Systematics, 27 (1), 305-335.
Corlette, R. and Primack, R. 2005. Dipterocarps: Trees that dominate the Asian rainforest. Arnoldia, 63 (3), 3-7.
DENR. 2017. Department of Environment and Natural Resources Administrative, Order No. 2017-11.
Dyer, L.A., Letourneau, D.K., Chavarria G.V. and Amoretti, S. 2010. Herbivores on a dominant understory shrub
increase local plant diversity in rainforest communities. Ecology, 91, 3707-3718.
IUCN. 2020. IUCN Red list of threatened species. Retrieved from https://www.iucnredlist.org
Jactel, H., Moreira, X. and Castagneyrol, B. 2017. Tree div net insect herbivory assessment. Retrieved fromhttps://treedivnet.ugent.be/protocols/TDN_InsectHerbivoryAssessment.pdf
Langenberger, G. 2006. Habitat distribution of dipterocarp species in the Leyte Cordillera: An indicator forspecies–site suitability in local reforestation programs. Annals of Forest Science, 63 (2), 149-156.
Machado, B.B., Orue, J.P., Arruda, M.S., Santos, C.V., Sarath, D.S., Goncalves, W.N. and Rodriguez Jr, Jf. 2016.
Bioleaf: A professional mobile application to measure foliar damage caused by insect herbivory. Computers
and Electronics in Agriculture, 129, 44-55.
Maron, J.L. and Crone, E.E. 2006. Herbivory: Effects on plant abundance, distribution and population growth.
Proceedings of the Royal Society B: Biological Sciences, 273:25752584.
Norghauer, J.M. and Newbery, D.M. 2013. Herbivores equalize the seedling height growth of three dominant tree.
Statistical Package for Social Sciences (SPSS). 2011. IBM SPSS statistics for windows. Version 20.0. Armonk,NY, IBM Corp.
The Plant List. 2013. Version 1.1. Published on the internet, Retrieved from http://www.theplantlist.org/Ⓒ ISERD

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