bluuebunny/crossref_metadata_2025 huggingface dataset:
Dispersal of the exotic parasitoid Cotesia flavipes in a new ecosystem
Authors: Sallam M.N. , Overholt W.A. , Kairu E.
Published: October 2003

A study on the dispersal of the exotic larval endoparasitoid, Cotesia flavipes Cameron (Hymenoptera: Braconidae), was conducted in a maize field in the northern Kilifi District in the coastal area of Kenya. Because C. flavipes did not previously occur in the release area, it was possible to use a unique indirect method to estimate dispersal by examining the distribution of parasitised hosts. Parasitoids released in the centre of the field moved as far as 64 meters during their life span, and dispersal was dependent on wind direction. The level of parasitism was influenced by the location of hosts in plants. The majority of parasitised stemborers (88.4%) were found inside the plant (stems and tassel stems), where 74.3% of the suitable hosts were found, which indicates that female parasitoids were not searching randomly for hosts. Aggregation of parasitoids in response to plants with different host densities was not detected. Implications of the release of C. flavipes on stemborers population in the agroecosystem of East Africa are discussed.
The use of barrier‐connected pitfall trapping for sampling predatory beetles and spiders
Authors: Winder L. , Holland J.M. , Perry J.N. , Woolley C. , Alexander C.J.
Published: October 2003

The efficiency of barrier‐connected pitfall trapping was compared to conventional single traps or arrays. For ground‐active beetles, the use of a pitfall system incorporating a wetting agent with five traps arranged in a cross formation connected by plastic barriers was more efficient than a single dry trap by at least an order of magnitude and at least twice as efficient as five traps without connecting barriers. It is argued that the efficiency of pitfall trapping may be improved markedly by using barrier‐connected traps, particularly for some carabid and staphylinid beetles and lycosid spiders. Capture of linyphiids was not improved by the use of barriers and was dependent only on the use of wetting agent and number of traps used.
Factors affecting mitochondrial DNA quality from museum preserved Drosophila simulans
Authors: Dean Matthew D. , Ballard J. William O.
Published: October 2003

In this study we investigate how traditional killing methods and storage regimes affected mitochondrial DNA quality in Drosophila simulans. Here we define quality with three criteria: (1) size of extracted DNA, (2) extraction yield, and (3) ability to amplify from four target regions. Killing methods had a significant effect on extraction yield, but not on PCR success. Highest DNA yields were extracted from specimens exposed to cyanide, while the lowest were from specimens killed in 70% ethanol. Specimens stored for two years contained badly sheared DNA, which translated into a significant decrease in PCR success compared to freshly assayed specimens. The most dramatic decrease in PCR success occurred in the 1822 bp and 1332 bp amplicons, compared to the 959 bp and 291 bp fragments. Naphthalene did not affect any aspect of DNA quality; time of storage affected PCR success regardless of naphthalene environment. This study serves to further refine our understanding of DNA degradation.
The potential of Chrysoperla rufilabris and Doru taeniatum as agents for dispersal of Spodoptera frugiperda nucleopolyhedrovirus in maize
Authors: Castillejos Vasty , García Luis , Cisneros Juan , Goulson Dave , Cave Ronald D. , Caballero Primitivo , Williams Trevor
Published: October 2003

The behaviour of two abundant predators in Mesoamerican maize crops, Chrysoperla rufilabris larvae and Doru taeniatum adults, towards healthy and nucleopolyhedrovirus‐infected Spodoptera frugiperda larvae was compared. C. rufilabris did not discriminate between healthy and virus‐infected prey, although the mean search time was approximately two times longer towards virus‐infected larvae. In contrast, D. taeniatum directed a greater proportion of their attacks towards virus‐infected prey but there was no significant difference in the search time. Prey consumption time did not differ significantly for each type of prey by either predator, although prey consumption was much faster in D. taeniatum. Viable virus was detected in D. taeniatum faeces up to 3 d after feeding on infected S. frugiperda larvae, whereas virus was inactivated in the gut of C. rufilabris. Both predators were shown to have acidic guts. A field experiment demonstrated that D. taeniatum that had fed on infected prey could contaminate foliage resulting in the transmission of the disease at a low prevalence (4.7%) to S. frugiperda larvae in a field maize crop.
Mating compatibility, life‐history traits, and RAPD‐PCR variation in Bemisia tabaci associated with the cassava mosaic disease pandemic in East Africa
Authors: Maruthi M.N. , Colvin J. , Seal S.
Published: October 2003

The pandemic of a severe form of cassava mosaic virus disease (CMVD) in East Africa is associated with abnormally high numbers of its whitefly vector, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). To determine whether a novel B. tabaci biotype was associated with the CMVD pandemic, reproductive compatibility, fecundity, nymphal development, and random amplified polymorphic DNA (RAPD) variability were examined in, and between, B. tabaci colonies collected from within the CMVD pandemic and non‐pandemic zone in Uganda. In a series of reciprocal crosses carried out over two generations among the six CMVD pandemic and four non‐pandemic zone cassava B. tabaci colonies, there was no evidence of mating incompatibility. All the crosses produced both female and male progeny in the F1 and F2 generations, which in a haplo‐diploid species such as B. tabaci indicates successful mating. There also were no significant differences between the sex ratios for the pooled data of experimental crosses, between individuals from two different colonies and control crosses between individuals from the same colony. Only one instance of mating incompatibility occurred in a control cross between cassava B. tabaci from Uganda and cotton B. tabaci from India. Measures of fecundity of the pandemic and non‐pandemic zone B. tabaci on four cassava varieties showed no significant differences in their fecundity, nymphal development or numbers surviving to adult eclosion. Cluster analysis of 26 RAPD bands using six 10‐mer primers was concordant with the mating results, grouping the pandemic and non‐pandemic zone colonies into a single large group, also including a B. tabaci colony collected from cassava in Tanzania. These results suggest that it is unlikely that the severe CMVD pandemic in East Africa is associated with a novel and reproductively isolated B. tabaci biotype.
The dynamics of second‐ and third‐male fertilization precedence in Tribolium castaneum
Authors: Arnaud Ludovic , Gage Matthew J.G. , Haubruge Eric
Published: October 2003

Sperm precedence is a useful descriptor of the outcome and possible processes of sperm competition between (usually) two males. Although sperm precedence values are known for a variety of taxa, a characteristic feature has been the profound, and largely unexplained, variance in precedence. In this study we partition some of the precedence variance in Tribolium castaneum (Herbst) (Coleoptera, Tenebrionidae) by examining how: (1) sperm precedence changes with time over a one‐month oviposition period, (2) precedence is influenced by the relative timing of the two competitive mating periods, and (3) sperm precedence is affected when three, rather than the normal two, males are placed in sperm competition. In general, last male sperm precedence is high (≈ 90%) for the first few days after mating, but this changes significantly with time as previous males' sperm become used in fertilization. We find that the duration between two competitive mating bouts has a significant effect on precedence (even when relatively brief): longer intervals between mating bouts result in more complete and persistent last‐male sperm precedence. The dynamics of last‐male sperm precedence when there are three males in the competition are not significantly different to precedence results when only two males are in competition. Our results are consistent with the hypothesis that, soon after inseminations, male ejaculates ‘stratify’ in the narrow and elongate storage tubules of the spermatheca. With time we see increased variance in individual male precedence as sperm from previous matings achieve more fertilizations. This change over time may result from depletion (either via fertilizations or passive/active sperm loss) of the last males' sperm and/or increased mixing of different males' sperm within the spermatheca.
Induction of systemic acquired resistance in cotton by BTH has a negligible effect on phytophagous insects
Authors: Inbar Moshe , Doostdar Hamed , Gerling Dan , Mayer Richard T.
Published: October 2003

Whether or not chemical changes in plants in response to pests (insects and pathogens) are general or specific remains unclear. Some evidence indicates that an induced response (IR) to arthropods via the octadecanoid pathway represents a distinct mechanism from the salicylic acid‐based pathway of systemic acquired resistance (SAR) to pathogens. To further test this hypothesis, young cotton seedlings were activated with benzo (1,2,3) thiadiazole‐7‐carbothioic acid (S) methyl ester (BTH), an elicitor of SAR. The enzymatic activities of a number of pathogenesis‐related (PR) proteins in young and old leaves of control and BTH treated plants were measured. BTH applications elicited marked increases in the activity levels of chitinase, peroxidase, and β‐1,3‐glucanase both locally and systemically. The highest levels of induction were detected systemically in young leaves. Except for some local effects on whitefly oviposition, the induction of SAR by BTH had no effect on either host preference of whiteflies Bemisia tabaci (Gennadius) or on feeding efficiency of cotton bollworms Helicoverpa armigera (Hübner). We conclude that SAR induction via the salicylic acid pathway in ‘Acala’ cotton has negligible effect on the tested insect herbivores.
Antimetabolic effects of plant lectins towards nymphal stages of the planthoppers Tarophagous proserpina and Nilaparvata lugens
Authors: Powell K.S.
Published: October 2003

Taro Colocasia esculenta (L. Schott) and rice (Oryza sativa L.) form a major part of the staple diet of pacific islanders. Pest constraints hamper the sustainability of taro and rice production in the Pacific region. Insect feeding trials were conducted in vitro to determine the effects of plant lectins against planthopper pests of taro and rice. Lectins were incorporated into artificial diet at 0.1% (w/v) level. The lectins Galanthus nivalis agglutinin (GNA) and concanavalin A (Con A) showed significant antimetabolic effects towards third instar nymphs of taro planthopper (Tarophagous proserpina Kirkaldy) whilst Pisum sativum agglutinin (PSA) showed no significant effects toward the insect. Psophocarpus tetragonolobus agglutinin (PTA) showed significant antimetabolic effects towards third instar nymphs of rice brown planthopper (Nilaparvata lugens Stål). PTA also reduced honeydew excretion levels of rice brown planthopper, over a 24‐hour period, demonstrating antifeedant properties of the protein.
Effects of soybean proteinase inhibitor on development, survival and reproductive potential of the sugarcane borer, Diatraea saccharalis
Authors: Pompermayer P. , Lopes A.R. , Terra W.R. , Parra J.R.P. , Falco M.C. , Silva‐Filho M.C.
Published: October 2003

One approach that can be employed in integrated pest management is the use of proteins with antinutritional effects on insect metabolism and development. The antimetabolic properties of soybean proteinase inhibitor (SPI) on growth of neonate larvae of the sugarcane borer, Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) have been evaluated. When incorporated into an artificial diet at 0.5% (w/w), SPI retarded growth rate and development of larvae when compared with larvae fed on artificial diet alone. However, larval survival was not significantly affected. The purpose of our research was to calculate demographic statistics for the sugarcane borer reared on diet either with or without semi‐purified extract of SPI. Net reproductive rate (R0), instantaneous rate of increase (rm), combined age‐specific survivorship (lx) and age specific fecundity (mx) provide information about population growth potential. These parameters were measured in order to determine the effects of the proteinase inhibitor on the insect's population dynamics. The observed differences would potentially translate into large reductions in population growth, indicating a potential value of using SPI for protecting sugarcane plants against damage by the sugarcane borer.
Why are seed cones of Swiss stone pine (Pinus cembra) not attacked by the specialized pine cone weevil, Pissodes validirostris? A case of host selection vs. host suitability
Authors: Dormont L. , Roques A.
Published: October 2003

The pine cone weevil, Pissodes validirostris Gyll. (Coleoptera: Curculionidae), attacks seed cones of most Eurasian pine species, except these of Swiss stone pine (Pinus cembra L.). Behavioural responses of adult weevils to cone volatile emissions of Swiss stone pine and to those of a common host, mountain pine (Pinus uncinata Ram.), were compared in an olfactometer. Weevils were significantly attracted by the volatile blend emitted by mountain pine, but Swiss stone pine volatiles elicited an inverse response, with most weevils moving in the opposite direction to the odour source. However, the majority of second instar weevil larvae that were extracted from mountain pine cones and transferred into Swiss stone pine cones were capable of developing to the adult stage. This suggests that Swiss stone pine cones do not contain strong feeding deterrents that could prevent larval development. The possible factors involved in the absence of colonization of Swiss stone pine cones by cone weevils are discussed.
Flower nitrogen status and populations of Frankliniella occidentalis feeding on Lycopersicon esculentum
Authors: Brodbeck Brent V. , Stavisky Julianne , Funderburk Joseph E. , Andersen Peter C. , Olson Steven M.
Published: October 2003

In a 2‐year study, we manipulated flower chemistry of field grown Lycopersicon esculentum in North Florida and examined subsequent effects on populations of Frankliniella occidentalis. We examined variation in amino‐acid profiles and total nitrogen concentrations of flowers, flower number and plant size seasonally and in response to variable rates of nitrogen fertilization (202 kg ha−1 and 309 kg ha−1). Populations of F. occidentalis sampled every 6 to 10 days were then related to seasonal and treatment effects on plant variables. For both years, F. occidentalis was abundant on L. esculentum tomatoes for only short intervals (2–3 weeks), and populations were significantly higher on hosts receiving higher rates of nitrogen fertilization. Seasonal trends in F. occidentalis on L. esculentum were correlated to number of flowers per host plant, as well as concentrations of total nitrogen in flowers. Moreover, treatment (fertilization) effects were consistent with changes in the nitrogen status of flowers. Plants subjected to higher fertilization rates produced flowers that had higher nitrogen content as well as variations in amino‐acid profiles during the period of peak thrips populations. Abundance of F. occidentalis (particularly adult females) were most highly correlated to flower concentrations of phenylalanine during population peaks. Our results are consistent with beneficial effects of high dietary nitrogen to thrips populations, and also support the hypothesis that aromatic amino acids (e.g., phenylalanine) play a central role in the nutritional ecology of F. occidentalis.
Different approaches to labelling parasitoids using strontium
Authors: Gu Hainan , Wäckers Felix , Steindl Philippe , Günther Detlef , Dorn Silvia
Published: October 2003

Labelling parasitoids with trace elements is a potentially powerful technique for studying dispersal and trophic interactions in these usually small insects. Laboratory experiments were conducted to investigate the feasibility and efficiency of different methods for trace element labelling of the hymenopteran parasitoid Cotesia glomerata. We concentrated on Sr as a marker and in some relevant aspects also compared its labelling efficiency to that of Rb, which is the trace element commonly used to label insects. Laboratory‐reared wasps had a mean background level of 0.43±0.26 (SD) μg g−1 for strontium (Sr) and 0.51±0.25 (SD) μg g−1 for rubidium (Rb), which was much lower than that for seven other common trace elements (i.e. B, Mg, Al, Ca, Fe, Cu, and Zn). Cotesia glomerata could be effectively labelled with Sr by: (1) feeding adults on sucrose solution spiked with Sr; (2) rearing larvae from Pieris brassicae fed the cabbage plant (Brassica oleracea) soil‐drenched with aqueous Sr; or (3) feeding adults on extrafloral nectar from a plant (Vicia faba) soil‐drenched with aqueous Sr. Although Sr content in labelled wasps varied with the concentration and the method applied, it did not decline significantly with age. Labelled wasps could be unequivocally distinguished from unlabelled counterparts even 16 days after they were denied access to the Sr‐enriched food sources. Labelling with Sr did not seem to have any negative effect on the parasitoid fitness. Thus, Sr is an ideal internal marker to label C. glomerata and other hymenopteran parasitoids for investigations of bi‐ and tri‐trophic interactions.
Differences in morphology and reproductive traits of Galerucella nymphaeae from four host plant species
Authors: Pappers Stephanie M. , van Dommelen Harm , van der Velde Gerard , Ouborg N. Joop
Published: October 2003

The water lily beetle Galerucella nymphaeae L. (Coleoptera: Chrysomelidae) exploits different hosts, including Nuphar lutea Sm. and Nymphaea alba L. (both Nymphaeaceae), as well as Polygonum amphibium L. and Rumex hydrolapathum Hudson (both Polygonaceae). The present study investigates whether within‐species differences in morphological and reproductive traits are associated with differences in host species exploitation. A total of 1103 adult beetles were collected from 11 localities in The Netherlands, one of which contained all four hosts and three other localities contained hosts from both families (sympatric localities). Adults originating from Nuphar and Nymphaea were on average darker in colour and larger in size and had disproportionally bigger mandibles than beetles originating from Polygonum and Rumex across the 11 localities. Head capsules of first instar larvae from Nymphaeaceae hosts were between 17% and 28% larger than those of larvae from Polygonaceae hosts. Furthermore, beetles from Nuphar and Nymphaea laid larger sized eggs, but fewer eggs per clutch than beetles originating from Polygonum and Rumex. Although host related variation was less pronounced at the sympatric localities than in the allopatric localities, differences in larval and adult size were still highly significant at the sympatric localities. It is not clear whether the observed differences are genetically based, as opposed to host induced. However, leaf toughness varied among species in a way suggesting that leaf toughness may be partly responsible for host related differences in G. nymphaeae.
Chitinolytic enzymes from Streptomyces albidoflavus expressed in tomato plants: effects on Trichoplusia ni
Authors: Gongora Carmenza E. , Wang Shaojiu , Barbehenn Raymond V. , Broadway Roxanne M.
Published: October 2003

Tomato (Lycopersicon esculentum) cultivars were transformed with genes that encode bacterial chitinolytic enzymes (i.e., endochitinase and chitobiosidase) from Streptomyces albidoflavus. Transgenic tomato plants producing these enzymes were found to have enhanced resistance to cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), consistently reducing the growth rates of larvae. Mortality was significantly increased in two of three feeding trials. Ingestion of endochitinase and chitobiosidase not only affected development of larval T. ni from neonate to ultimate instar, but they also caused mortality and decreased insect weight when exposure began during the third instar. The results of this study provide some insight into the mode of action of the chitinolytic enzymes, by supporting the hypothesis that ingested chitinolytic enzymes damage the chitin component of the peritrophic envelope, leading to increased permeability. The size of marker molecules (FITC‐dextrans) that permeated the peritrophic envelopes of T. ni feeding on transgenic plants were 50% larger than those permeating the peritrophic envelopes of T. ni feeding on the control plants. Further research is needed to more clearly identify the sites and modes of action of these chitinolytic enzymes, and the potential for synergy between these enzymes and pathogens, allelochemicals, and other environmental factors.
Antibiotic curing of parthenogenesis in Eretmocerus mundus (Australian parthenogenic form)
Authors: De Barro P.J. , Hart P.J.
Published: October 2003

The thelytokous parasitoid, Eretmocerus mundus (Australian parthenogenetic form) was infected with a species of Group B Wolbachia. Antibiotic treatment of the parasitoid cured parthenogenesis and lead to male production and reduced egg hatching by virgin females. For each generation infected females produced more progeny than cured females. The descendants of individuals treated with antibiotic were in most cases free of a detectable infection. Both treated females and descendant females mated and received sperm, but these were not used as mated and unmated cured females produced offspring with a similar sex ratio. Males produced as a result of the antibiotic treatment were at least partially functional as they produced sperm and copulated with and inseminated females. However, no sexual line could be established.
Host marking behavior in phytophagous insects and parasitoids
Authors: Nufio César R. , Papaj Daniel R.
Published: October 2003

Oviposition behavior in phytophagous insects and entomophagous parasitoids is often modified by the presence of conspecific brood (eggs and larvae). Often, females avoid laying eggs on or in hosts bearing brood, a behavior that acts to reduce the level of competition suffered by their offspring. Avoidance of occupied hosts is typically mediated by cues and/or signals associated with brood. In this article, we review the role of Marking Pheromones (MPs) as signals of brood presence in both phytophagous and entomophagous insects. We place information about the function and evolution of MPs in the context of recent theory in the field of animal communication. We highlight the dynamics of host‐marking systems and discuss how effects of MPs vary according to factors such as female experience and egg load. We also examine variation in the form and function of MP communication across a variety of insect taxa. While studies of MP communication in phytophagous insects have focused on the underlying behavioral mechanisms and chemistry of MP communication, studies in entomophagous insects have focused on the functional aspects of MPs and their role in ‘decision‐making’ in insects. We argue that an approach that incorporates the important contributions of both of these somewhat independent, but complementary areas of research will lead to a more complete understanding of MPs in insects. Finally, we suggest that MP systems are model systems for the study of animal signaling and its evolution.
Embryonic development of orchard leafrollers and the forecasting of egg hatch
Authors: Blommers L.H.M. , Helsen H.H.M. , Vaal F.W.N.M.
Published: October 2003

The development time of eggs of three of the most noxious leafrollers found in Northeuropean orchards, Spilonota ocellana (Denis & Schiffermüller), Archips podana (Scopoli), and Pandemis heparana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) was recorded in the laboratory at five constant temperatures between 14 and 25 °C. In this range, developmental rates of the three species did not differ significantly. While the flight periods of these species overlap largely, a single algorithm could be used to devise optimal spraying time(s) for the three species.
Flight potential and oxygen uptake during early dormancy in Coccinella septempunctata
Authors: Nedvěd Oldřich , Ceryngier Piotr , Hodková Magdalena , Hodek Ivo
Published: October 2003

Two flight parameters (take‐off and duration) and respiration level were measured, in two years in summer and early autumn, in dormant Coccinella septempunctata L. (Coleoptera: Coccinellidae) collected while hidden in grass tussocks in hibernation sites (HID) and in beetles collected on plants (PLA). The duration of tethered flight of HID beetles measured in the laboratory in late August and September 1995 (range of geometric means 190–440 s) was slightly longer than the flight of PLA beetles (80–310 s), both being much longer than trivial flight recorded in beetles foraging for prey during the breeding season (35 s). In general, the flight performance had a tendency to increase in September and to decrease in October.

The oxygen consumption in HID beetles increased throughout September 1994 from 430 to 780 μl g−1 h−1 and throughout October 1995 from 710 to 1060 μl g−1 h−1. This increase is ascribed to a concomitant decrease in diapause intensity. A similar increase was observed also in PLA beetles in 1994 and oxygen consumption was always higher than in HID beetles, most probably due to feeding and digestion in PLA beetles.

Laboratory feeding of HID beetles on aphids induced maturation of ovaries and increased oxygen uptake (from 680 to 1110 μl g−1 h−1). Feeding on honey and pollen left their oxygen uptake unchanged. Effect of feeding on the flight parameters was mostly not significant. In agreement with its less suitable body shape and usually less distant dormancy sites, C. septempunctata was found a less apt flier than long‐distance migrating coccinellid species.
Interactions between host attributes and wasp size: a laboratory evaluation of Trichogramma platneri as an augmentative biological control agent for two avocado pests
Authors: Honda Jeffrey Y. , Luck Robert F.
Published: October 2003

We compared egg parasitization of two sporadic pests of avocado, Persea americana Miller, by Trichogramma platneri Nagarkatti reared on Sitotroga cerealella (Oliver) (=smaller parasitoids) with those reared on Trichoplusia ni (Hübner) (= larger parasitoids) in the laboratory. Large T. platneri females invested less time than smaller parasitoids in obtaining offspring from eggs of either Amorbia cuneana Walsingham or Sabulodes aegrotata (Gueneé). Furthermore, large T. platneri invested substantially more time (ca. 3‐fold) in obtaining offspring from S. aegrotata than A. cuneana eggs. These investment times positively correlated with percentage egg‐load retained by a female after it had ceased exploiting a host species. This occurred even though the offspring produced by a parasitoid from either host species manifested the same size and fecundity (= quality). Host species utilization in the laboratory mirrored that observed in the avocado groves of southern California following augmentative release of commercially produced T. platneri (Oatman & Platner, 1985). Explanations for these differences in host utilization are discussed along with their implications for augmentative biological control.
Specialisation pattern of the aphid Rhopalosiphum maidis is not modified by experience on a novel host
Authors: Caballero Paula P. , Ramírez Claudio C. , Niemeyer Hermann M.
Published: October 2003

The effect of alternative host condition on the pattern of specialisation of the aphid Rhopalosiphum maidis (Fitch) was studied. R. maidis commonly occurs in Chile on Johnson grass (Sorghum halepense L.) but rarely on contiguous wheat (Triticum durum L.) crops. The performance of 23 clones of R. maidis on S. halepense (established host) and T. durum (novel host) before and after rearing on wheat for 20 asexual generations was evaluated. Prior and after the period of conditioning on wheat no negative correlation of performance parameters between both hosts was found. Only 8 out of 23 clones survived the 20 asexual generations on wheat. Further, after conditioning on wheat, survival of three out of eight clones increased on wheat and three clones improved rm on Johnson grass but not on wheat. Although some genotypes of R. maidis were able to withstand wheat stressing conditions, the conditioning on this alternative host did not cause a decreased capacity to use Johnson grass as host. The results suggest that R. maidis performance on wheat is not genetically constrained, and also that conditioning on wheat cannot substantially modify this pattern.
Rearing of the pupal parasitoid Brachymeria intermedia on veal homogenate‐based artificial diets: evaluation of factors affecting effectiveness
Authors: Dindo M.L. , Farneti R. , Baronio P.
Published: October 2003

The pupal parasitoid Brachymeria intermedia (Nees) was reared from egg to fecund adult on various veal homogenate‐based artificial diets. For every replicate 12.12 ml of each diet were used. Four diets were tested first. Two media, one devoid of and one supplemented with 1 ml Galleria mellonella pupal extract, contained 0.19 g wheat germ and 0.19 g yeast extract each. The other two, one added with and the other devoid of host extract, contained 0.38 g yeast extract each and no wheat germ. All diets also contained chicken egg yolk (1.1 and 0.8 ml in the diets without and with host extract, respectively). The amount of yeast extract was seen to have no significant effect on any of the developmental parameters considered. The replacement of wheat germ with yeast extract was therefore not convenient, considering that the former is far more economical than the latter. Pupal extract was instead found to have a significant effect on pupal and adult yields. The highest adult yield (= 53.2%) was obtained on the diet supplemented with 0.38 g yeast extract and containing host pupal extract. A further four media, each comprising a different kind of material derived from G. mellonella, were subsequently tested. Adult yields were such as to suggest the possibility of replacing pupal with larval extract in the diets as the latter is easier to prepare since there are no cocoons to be removed. In contrast, when the diets were supplemented with larval or pupal homogenate, adult yields dramatically dropped. When B. intermedia was reared in groups rather than individually, most larvae died before attaining maturity. Only two parasitoids, in two different replicates, emerged as adults.
Pesticide‐induced susceptibility of rice to brown planthopper Nilaparvata lugens
Authors: Wu Jin‐cai , Xu Jian‐xiang , Yuan Shu‐zong , Liu Jing‐lan , Jiang Yong‐hou , Xu Jun‐feng
Published: October 2003

The effects of rice plants treated with various pesticides (jingganmycin, bisultap and methamidophos) on feeding, survival rates and population growth of Nilaparvata lugens Stål (Homoptera: Delphacidae), susceptibility of the treated rice plants and amounts of free amino acids and sucrose were studied. Experiments indicated that the effects of the tested pesticides were dependent on nymphal age, pesticide and their dose and time after application. Jingganmycin at 75 g a.i. ha−1 significantly increased the N. lugens population. Both jingganmycin and bisultap increased the survival rate of N. lugens nymphs. The feeding rate of the insects was also affected by the pesticide application, but the effect varied between nymphal age and time after application and lasted no longer than 15 d. Results clearly indicated that pesticide application increased the susceptibility of rice plants to N. lugens. Although the free amino acids in rice plants did not change with the pesticide treatments, the concentration of sucrose significantly decreased 5 d after application and the C/N ratio significantly decreased in jingganmycin treated plants 5 d and 10 d after application.
Factors affecting density‐independent survival of an island population of tsetse flies in Zimbabwe
Authors: Hargrove J.W.
Published: October 2003

Analysis is presented of the factors affecting survival probability in populations of tsetse flies Glossina morsitans morsitans Westwood and G. pallidipes Austen (Diptera: Glossinidae) on Antelope Island, Lake Kariba, Zimbabwe. For mature male and female adult G. m. morsitans mean temperature (Tbar) accounted for 70 and 50%, respectively, of the variance in mark‐recapture estimates of survival when the flies were not subjected to trapping. Saturation deficit (SD) only accounted for 36 and 33%, respectively. Maximum temperature (Tmax) and SD accounted for 36–42% of the variance in male and female G. pallidipes. For the corresponding Moran curve estimates of the survival over all developmental stages, SD lagged by three weeks accounted for 61 and 41% of the variance for male and female G. m. morsitans, respectively, and 64 and 56% for G. pallidipes. The corresponding figures for plots against Tmax were 44, 23, 23, and 21%, respectively. The same patterns were seen in the whole data set once allowance was made for the effect of trapping on survival and for an effect of season, correlated with an index of photosynthetic activity. For male G. m. morsitans there was a significant effect of saturation deficit, but not temperature, on immature survival. Decreased adult survival at high temperatures results from the need to feed more frequently and hence to take more risks per unit time. High saturation deficits result directly in reduced emergence of healthy flies from pupae.
Quantitative aspects of the regulation of ovarian development in selected anautogenous Diptera: integration of endocrinology and nutrition
Authors: Browne L. Barton
Published: October 2003

Aspects of the influence of nutrition on the degree of ovarian development in selected anautogenous Diptera are reviewed. The Diptera considered are several mosquito species, with emphasis on Aedes aegypti, the house fly, Musca domestica, the Australian bush fly, M. vetustissima and the blowflies, Lucilia cuprina and Phormia regina. All the selected species display discrete ovarian cycles in which all oocytes destined to reach maturity in a particular ovarian cycle develop synchronously. In these species, the proportion of females maturing oocytes and, where such data exist, the number of oocytes they mature are positively correlated with the amount of any particular nitrogen‐containing material ingested or given by enema or by infusion. In addition, the degree of ovarian development may be affected by the chemical composition of nitrogen‐containing food. Possible physiological bases for the observed relationships are discussed. Available evidence suggests that whether or not a female matures any oocytes is hormonally regulated and that the number of oocytes matured is probably regulated by the availability of nutrients. Some approaches that might further elucidate the physiological regulatory mechanisms involved in ovarian development are outlined.
Modeling evolution of behavioral resistance by an insect to crop rotation
Authors: Onstad D.W. , Spencer J.L. , Guse C.A. , Levine E. , Isard S.A.
Published: October 2003

Crop rotation has traditionally been a valuable method for managing pests, but now a serious insect pest of maize (Diabrotica virgifera virgifera LeConte [Coleoptera: Chrysomelidae]) has developed behavioral resistance to rotation. A simple model of adult behavior and population genetics can explain how this resistance may have developed. This general model indicates that evolution may be caused by selection on a single gene for adult movement and that behavioral resistance only develops at high levels of rotation (>80% of plant landscape). In less diverse landscapes, crop rotation selects for the expansion of host preferences (polyphagy) by adults. More diverse landscapes may delay the evolution of resistance to crop rotation depending on the fitness costs and the nature of the genetic system.
Timing of diapause induction outside the natural distribution range of a species: an outdoor experiment with the bean bug Riptortus clavatus
Authors: Musolin Dmitry L. , Numata Hideharu , Saulich Aida H.
Published: October 2003

The phytophagous bug Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) produces two or three generations per year in Central Japan and overwinters in the adult stage. In bugs from the Kyoto population (35°00′ N, 135°45′ E), we studied (1) the effects of day‐length on the nymphal and preoviposition periods under constant photoperiod at 20.5 °C, and (2) photoperiodic induction of adult diapause at 20.5 °C and under a combination of constant photoperiod and natural daily rhythm of temperature in the forest‐steppe zone of Russia (50°38′ N, 35°58′ E). Then, we examined (3) the timing of diapause induction under quasi‐natural conditions in the same region, far outside the species' natural geographical range. At 20.5 °C, the nymphal period in both males and females was significantly longer under regimes with shorter photophases than under those with longer photophases. The preoviposition period in females was significantly longer under the near‐critical long‐day regime L14:D10 than under typical long‐day regimes (L15:D9, L16:D8, and L17:D7). The critical day‐length for diapause induction was shorter under conditions of natural daily rhythm of temperature than those reported at constant 20, 25, and 30 °C. Under quasi‐natural conditions in the forest‐steppe zone, R. clavatus entered diapause in September, much later than the local populations of true bugs studied to date. This experiment showed that R. clavatus was maladapted to new environmental conditions: diapause was induced too late with the result that all or most nymphs hatched in late August or early September will die.
Irreversible thelytokous reproduction in Muscidifurax uniraptor
Authors: Gottlieb Yuval , Zchori‐Fein Einat
Published: October 2003

Vertically transmitted bacteria of the genus Wolbachia are obligatory endosymbionts known to cause thelytokous (asexual) reproduction in many species of parasitic Hymenoptera. In these species production of males can be induced, but attempts to establish sexual lines have failed in all but one genus. We have found three reproductive barriers between antibiotic‐induced males and conspecific females of Muscidifurax uniraptor Kogan and Legner (Hymenoptera: Pteromalidae): males do not produce mature sperm, females are reluctant to mate, and a major muscle is absent from the spermatheca. These findings suggest that Wolbachia‐induced thelytokous reproduction in M. uniraptor is irreversible, and are consistent with the idea that since sexual reproduction has ceased, selection on sexual traits has been removed leading to the disappearance or reduction in these traits. Because under these circumstances asexual reproduction is irreversible, the host has become totally dependent on the symbiont for reproduction.
Encapsulation and hemocyte numbers in three lepidopteran stemborers parasitized by Cotesia flavipes‐complex endoparasitoids
Authors: Alleyne Marianne , Wiedenmann Robert N.
Published: October 2003

Determination of the potential and actual host range of a natural enemy is crucial before its importation and release for biological control. We studied some of the factors that are important in determining the physiological host range of insect parasitoids attacking lepidopteran hosts. Our experimental system consisted of novel host‐parasitoid associations, with two New World pyralid stalk borers, Diatraea saccharalis and D. grandiosella; one Old World crambid borer, Ostrinia nubilalis as hosts; and three Old World microgastrine braconids, Cotesia chilonis, C. sesamiae, and C. flavipes as parasitoids. Experiments on the chronology of encapsulation of the parasitoid progeny by host hemocytes indicated that lepidopteran stemborers that are taxonomically, behaviorally and ecologically very similar differ in their ability to encapsulate a parasitoid species. D. saccharalis encapsulated C. flavipes sometimes, whereas D. grandiosella consistently encapsulated C. sesamiae and C. flavipes. C. chilonis was not encapsulated by either Diatraea host. If encapsulation occurred it did not start until four days after parasitization and continued during the following days. O. nubilalis was an unsuitable host for all three parasitoid species; parasitoid eggs were killed within 24 hours of parasitization. O. nubilalis had nearly twice as many hemocytes present in the hemolymph compared to the Diatraea species. In many of the host‐parasitoid combinations, there was an initial increase of hemocyte number soon after parasitization, which was not due to mechanical damage at oviposition. There was no correlation between total numbers of hemocytes present in the host hemolymph and the observed encapsulation levels. By understanding the encapsulation response we may be able to make better predictions about the host range of a parasitoid species before its release as a biological control agent.
Does host‐feeding on GNA‐intoxicated aphids by Aphelinus abdominalis affect their longevity and/or fecundity?
Authors: Couty Aude , Poppy Guy M.
Published: October 2003

Transgenic potatoes have been transformed with a gene coding the snowdrop lectin Galanthus nivalis agglutinin (GNA) and they have been shown to be partially resistant to aphids. GNA binds to insect gut cells, including those of aphids, consequently inducing disruption of nutrient assimilation. Aphid parasitoids are important natural biocontrol agents of aphids and some species such as Aphelinus abdominalis are commercially available. Aphid parasitoids are endoparasitoids during their larval stages and free‐living insects as adults. They could be directly or indirectly affected by GNA during both these stages. In this work, we present data on the potential direct and indirect effects of GNA on adult A. abdominalis.

Aphelinus abdominalis is a synovigenic species (eggs are matured throughout the adult life) which needs a diet relatively rich in proteins and amino‐acids to produce anhydropic eggs (large, yolk‐rich eggs that do not expand in the host during embryonic stages). Adult A. abdominalis females feed on aphid haemolymph and they may be directly exposed to the entomotoxin or indirectly affected by a change in aphid haemolymph quality due to intoxication by GNA. We conducted a first tier experiment to investigate this potential risk. A. abdominalis females were offered either aphids reared on control diet or aphids reared on GNA 0.1% diet as hosts (i.e., as food and oviposition sites). No trace of GNA was found in females fed with GNA‐aphids but no GNA could be detected in the haemolymph of aphids fed a 0.1% GNA diet. Longevity and fecundity were not affected suggesting that the quality of the haemolymph necessary for A. abdominalis egg maturation and production was not significantly altered.
Stylet penetration and survival of three psyllid species on adult leaves and ‘waxy’ and ‘de‐waxed’ juvenile leaves of Eucalyptus globulus
Authors: Brennan Eric B. , Weinbaum Steven A.
Published: October 2003

The stylet probing behavior and survival of Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore (Homoptera, Psyllidae) on adult leaves and ‘waxy’ (untreated) and ‘de‐waxed’ (rubbed) juvenile leaves of the heteroblastic plant Eucalyptus globulus Labillardiere were compared. Psyllids were confined within clip‐on cages and after 15 days the leaf tissue under each cage was sectioned and stained to characterize and quantify stylet tracks. Across all leaf treatments and psyllid species 1438 stylet tracks were observed in 7239 leaf sections and 571 of these stylet tracks reached the vascular tissue. Survival and the number of stylet tracks of C. eucalypti on the different leaf types did not differ. In contrast, C. spatulata survived significantly longer and produced significantly more stylet tracks on adult leaves and ‘de‐waxed’ juvenile leaves than on ‘waxy’ juvenile leaves. Although G. brimblecombei survived equally on all treatments, it produced more stylet tracks on adult leaves and ‘de‐waxed’ juvenile leaves than on ‘waxy’ juvenile leaves. For all three psyllid species, there was a positive correlation between survival and number of stylet tracks reaching the vascular tissue. Stylet tracks of all species were generally intercellular from the leaf epidermis to the vascular tissue. Oil glands were avoided by all species, as indicated by the repeated branching and formation of stylet tracks at the periphery of the glands. In ‘de‐waxed’ juvenile leaves, C. spatulata and G. brimblecombei produced stylet tracks that entered the leaf at the adaxial surface and exited at the abaxial surface. This pattern was rarely observed on adult leaves, and never occurred with C. eucalypti in any leaf type. We conclude that (1) the epicuticular wax on juvenile leaves reduced stylet probing by C. spatulata and G. brimblecombei, (2) there were apparently no internal physical barriers in either juvenile or adult leaves to prevent the stylets of any of the psyllid species from reaching the vascular tissue, (3) the psyllids avoided oil glands in both leaf types, and (4) C. spatulata and G. brimblecombei may lack cues to orient their stylets towards the vascular tissue in the juvenile leaves.
Potential for habituation to a neem‐based feeding deterrent in Japanese beetles, Popillia japonica
Authors: Held D.W. , Eaton T. , Potter D.A.
Published: October 2003

We tested the potential for the Japanese beetle, Popillia japonica Newman, to habituate to a neem‐based feeding deterrent applied to foliage of linden, Tilia cordata L., a preferred host for the adults. Female beetles' consumption of control foliage versus foliage treated with either a low or high rate of neem insecticide, corresponding to 9 or 39 pm azadirachtin, respectively, was tested in a series of 4‐h choice or no‐choice tests over four successive days. In another experiment, females were conditioned for 22 h with either control foliage, leaves treated with the low rate, or a mixture of both treated and untreated leaves. Deterrence of either the low or high rate of neem to these beetles was then evaluated in choice tests with control foliage, as before. In choice tests, mean consumption of control foliage was always greater than for treated foliage, regardless of rate. There was, however, proportionately more feeding on foliage treated with the high rate upon successive exposures. In no‐choice tests, beetles initially deterred by the low rate were not significantly deterred by that rate by the third and fourth days of the experiment. Finally, beetles conditioned by exposure to leaves treated with the low rate were not deterred by that rate in a subsequent choice test, although they were deterred by the higher rate. Despite these trends, we suggest that Japanese beetles' polyphagy and mobility probably would reduce the likelihood for habituation to neem‐based feeding deterrents in the field.