bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure to avoid rutin diets results in altered food utilization and reduced growth rate of Manduca sexta larvae
Authors: Stamp N. E. , Skrobola C. M.
Published: April 2011

The possibility of avoidance of and dietary self‐selection relative to the flavonol rutin was examined for third instar Manduca sexta for two thermal regimes and for larvae previously reared on plain or rutin diet. Temperature affected all of the performance indices examined, except efficiency of conversion of digested food. Significant interactive effects between temperature and diet occurred for relative consumption rate, relative growth rate and the food utilization efficiencies. For example, at the warm daytime temperature, relative growth rate prior to head capsule slippage was lower for caterpillars previously reared on rutin diet compared to those reared on plain diet. In contrast, at the cool daytime temperature, the relative growth rates were similar for caterpillars reared on plain diet and on 6 μmoles rutin diet. Consequently, in some treatments (5 of 12), caterpillars with a history of rutin in their diet had lower relative growth rates than those experiencing rutin for the first time. Despite rutin's impact on food utilization indices and negative effect on relative growth rate, the caterpillars did not avoid rutin nor was there evidence of regulation of the intake of rutin. The lack of metabolic feedback is discussed.
Interaction of Manduca sexta resistance in tomato with insect predators of Helicoverpa zea
Authors: Barbour J. D. , Farrar R. R. , Kennedy G. G.
Published: April 2011

Resistance in accession PI 134417 of Lycopersicon hirsutum f. glabratum to Manduca sexta L. results from the presence of the methyl ketones 2‐tridecanone and 2‐undecanone in the type VI trichome glands on foliage of these plants. Short (24 h) and long term (neonate to adult) laboratory experiments using M. sexta‐resistant and susceptible foliage and methyl ketone treated filter paper disks were conducted to evaluate the direct (plant‐mediated) and indirect (prey‐mediated) effects of this resistance on two predators of Helicoverpa zea eggs, Coleomegilla maculata (DeGeer) and Geocoris punctipes (Say). Direct effects of resistance were manifest as reduced egg consumption and increased mortality for both predators. Indirect effects were manifest as reduced egg consumption by G. punctipes, but were not observed for C. maculata. Results of experiments using methyl ketone‐treated filter paper disks instead of foliage were similar.
Host race formation in Tetranychus urticae: genetic differentiation, host plant preference, and mate choice in a tomato and a cucumber strain
Authors: Gotoh T. , Bruin J. , Sabelis M. W. , Menken S. B. J.
Published: April 2011

The two‐spotted spider mite, Tetranychus urticae Koch, occurs in two colour forms in greenhouses in the Netherlands: a red form on tomato and a green form on cucumber. The evolutionary status of these strains was analysed by studying genetic differentiation, host plant preference, and mate choice. Males of the tomato strain preferred the female (30 h‐old) teleiochrysales from the same strain to those of the cucumber strain, independent of the host plants (tomato, cucumber, bean) on which the teleiochrysales were placed. In contrast, males of the cucumber strain were not selective. In a Y‐tube olfactometer, females of the cucumber strain were not responsive to host plant volatiles alone. However, in two‐choice disc experiments, where females were exposed to both volatile and contact cues, they settled on cucumber leaves in preference to tomato leaves. Females of the tomato strain preferred the odour of tomato leaves and settled on tomato leaves in preference to cucumber leaves. These experimental results provide the first evidence for (1) host‐plant independent mate selection in male spider mites and (2) olfactory discrimination between host plants in female spider mites.

Electrophoretic analysis showed much genetic differentiation at the phosphoglucose isomerase locus. The cucumber strain showed large variation with 5 alleles, whereas the tomato strain was fixed for the most common allele of the cucumber strain.

The results suggest that the two strains represent host races. We hypothesize that the tomato strain has originated from the cucumber strain because (1) tomato represents a more hostile host plant to spider mites (due to toxic compounds and glandular hairs) and (2) the tomato strain is genetically impoverished suggesting that it passed through one or more bottlenecks.
Behavioural responses of three linyphiid spiders to pitfall traps
Authors: Topping C. J.
Published: April 2011

The behaviour of three linyphiid spider species (Araneae: Linyhiidae) towards pitfall traps was investigated in an experimental arena. Capture efficiencies were low with a mean of between 16 and 57 traps being encountered before spiders were caught. Survival time, trap encounter rate, trap entry rate and reactions towards vegetation were all found to be species‐specific. These behaviours are considered to affect differentially pitfall trap efficiency and may partially explain the lack of clear relationship between pitfall trap catch and density found in published studies.
Toxicity of the fungal metabolite griseofulvin toHelicoverpa zeaandSpodoptera frugiperda
Authors: Dowd Patrick F.
Published: April 2011

Griseofulvin is a fungal metabolite that can be considered a mycotoxin but is used pharmaceutically to treat topical fungal infections. It was found to be toxic to both the corn earworm.Helicoverpa zeaBoddie, and the fall armyworm,Spodoptera frugiperda(J. E. Smith), at 250 ppm in diets. Its toxicity was enhanced by exposure to ultraviolet light, suggesting it can be photoactivated. Its toxicity was also enhanced by coincorporated δ‐amino levulinic acid, suggesting it interferes with porphyrin synthesis in these insects. Differences in toxicity and rates of metabolism caused by coincorporated piperonyl butoxide suggested unspecific monooxygenases were relatively more important in griseofulvin activation inH. zeaand detoxification inS. frugiperda.
Managing lepidopteran pests in cabbage with herbicide‐induced resistance, in combination with a pyrethroid insecticide
Authors: Eigenbrode Sanford D. , Shelton Anthony M. , Kain Wendy C. , Leichtweis Harry , Spittler Terry D.
Published: April 2011

S‐ethyldipropylthiocarbamate (EPTC) applied as a soil treatment or over‐the‐top spray on cabbage plants (Brassica oleracea L.) caused the leaves to turn ‘glossy’ for as long as 30 days. EPTC‐induced glossy plants were damaged significantly less than untreated plants by diamondback moth, Plutella xylostella (L.), imported cabbage worm, Pieris rapae (L.), and cabbage looper, Trichoplusia ni (Hbn.). Reductions in damage were equivalent to those obtained from treatment with permethrin. When used in combination with permethrin, EPTC provided additive control of damage by these pests. Our calculations show EPTC‐induced resistance to be cost‐effective. This use of EPTC has several limitations, however. Younger plants (<9 leaves) were killed or injured by the herbicide. The growth of older plants was not affected, but plants did not become glossy for ca. 10 days after they were treated with EPTC. The crop must be protected with insecticides until the plants are mature enough to treat with EPTC, and until treated plants become glossy. In addition, since the glossy trait is only effective against first instar larvae, populations of later instars on glossy plants must be reduced with an application of insecticide. Finally, EPTC formulations are water‐soluble and can be washed away from the plants by heavy rains and irrigation, which may make this use of EPTC impractical in some situations. Where its use is practical, and the indicated precautions are taken, EPTC‐induced resistance could reduce dependence on chemical insecticides and reduce selection for insecticide resistance in diamondback moth.
The inheritance of a wingless character in the 2spot ladybird (Adalia bipunctata)
Authors: Marples N. M. , de Jong P. W. , Ottenheim M. M. , Verhoog M. D. , Brakefield P. M.
Published: April 2011

A viable wingless 2spot ladybird Adalia bipunctata (L.) was found in the wild. Breeding through four generations revealed that the wingless trait was controlled by a recessive allele which displays variable levels of expression. The wingless ladybird is discussed in relation to its potential as a biocontrol agent. One ladybird also occurred in this stock which is suggestive of a supergene controlling the colour polymorphism in this species.
Bioassay for evaluating attraction of the phorid fly, Megaselia halterata to compost colonized by the commercial mushroom, Agaricus bisporus and to 1‐octen‐3‐ol and 3‐octanone
Authors: Pfeil R. M. , Mumma R. O.
Published: April 2011

A bioassay chamber was developed to evaluate the attraction of the phorid fly pest, Megaselia halterata (Wood) (Diptera, Phoridae), to volatiles from mushroom compost colonized by the commercial mushroom, Agaricus bisporus (Fungi, Agaricaceae) and to its volatile constituents, 1‐octen‐3‐ol and 3‐octanone. The bioassay chamber consisted of a large round container which was attached, via glass tubes, to three removable sample cups situated below the container. Once a fly had entered a sample cup, the flatly cut glass tubes prevented the flies from readily returning to the release chamber and, in effect, was a pit fall trap which kept the flies in the cups until the flies were counted. Holes in the bottom of the cups and removal of 20 ml of air from the chamber to fill the entrance tubes with volatiles from the cups were necessary for the success of the bioassay.

Mated and unmated female M. halterata and, to a lesser extent, mated males preferred spawned compost (compost well colonized by fungal mycelia) relative to unspawned compost or blank cups. Unmated males were not attracted to spawned compost. Males and females were not attracted to unspawned compost. No attraction of male or female M. halterata to the spawned compost volatiles, 1‐octen‐3‐ol and 3‐octanone, could be demonstrated under various experimental conditions. These two compounds seemed to deter females at high concentrations.
Production and electrophoretic verification of F1 hybrids between the sibling species Rhagoletis pomonella and R. cornivora
Authors: Smith D. C. , Lyons S. A. , Berlocher S. H.
Published: April 2011

To investigate the potential for natural interspecific hybridization in the Rhagoletis pomonella group of sibling fruit fly species, an attempt was made to hybridize R. pomonella, the apple maggot fly, with R. cornivora, a non‐pest feeding on dogwoods. Laboratory hybridization was difficult, with only five F1 hybrids produced. Electrophoretic analysis of the hybrids confirmed their hybrid origin. Allele frequency data for three diagnostic loci in up to 5,596 individuals of the parental species, gathered from published and unpublished studies, indicate that the two sibling species hybridize in nature very infrequently, if at all.
Associations of allozyme variation and behavior in the cowpea weevil (Callosobruchus maculatus)
Authors: Berg David J. , Mitchell Rodger
Published: April 2011

The cowpea weevil (Callosobruchus maculatus (Fabré)) exhibits several behavioral traits that are stable within, but vary among, strains. These traits are heritable and quantitative. We used cellulose acetate gel electrophoresis to quantify allozyme variation within and among laboratory cultures of four weevil strains and determine whether allozyme variation correlates with behavioral traits. Significant variation exists at 8 of 11 loci assayed and gene frequencies are significantly different among strains. The South Indian strain (SI) is most variable and measures of genetic distance set it apart from the other strains. It is also behaviorally unique. The Brazilian strain (BC) is most different from SI in allozyme diversity and behavioral phenotype, while two African strains (IITA, CAM) are intermediate in allozyme diversity and phenotype. These results are consistent with the known history of these strains and the differences in the allozymes parallel the differences in behavioral traits.
Chemosensory attraction of fig wasps to substances produced by receptive figs
Authors: Hossaert‐McKey M. , Gibernau M. , Frey J. E.
Published: April 2011

In the mutualism between figs (Ficus spp., Moraceae) and their species‐specific fig wasp pollinators (Hymenoptera: Agaonidae), location of a receptive host tree by the adult insect is a critical step. The adult female wasp lives only a few days, and must usually fly to a different tree than her natal tree to locate receptive figs. Trees in receptive phase often occur at very low densities. Reproductive success of both fig and wasp depends on transmission of a very strong signal by the plant. Some evidence exists for the role of olfaction in location of receptive hosts by fig wasps, but very little work has been done on the chemical ecology of host location and host specificity. Here the first experimental evidence is presented for long‐distance olfactory attraction of wasps by volatile substances produced by receptive figs, and for short‐distance or contact chemostimulation by host volatiles that elicit entry of the wasp into the fig. In studies using Ficus carica L., pentane extracts of receptive‐phase figs attract the pollinator Blastophaga psenes L. from distances of at least 5 m in the field. Short‐distance chemostimulation was demonstrated in laboratory bioassays. Pentane extracts of receptive figs, when painted onto the ostiole of non‐receptive figs, elicit entry of pollinator wasps. Figs emit volatile compounds attractive to pollinating wasps only during the period of receptivity; pentane extracts of non‐receptive figs are not attractive. A simple reliable procedure is described to compare the attractivity of different types of extracts (total, internal, and external extracts) and of different fractions, in the first step towards identifying attractant substances.
The protection of barley seedlings from attack by Schistocerca gregaria using azadirachtin and related analogues
Authors: Nasiruddin M. , (Luntz) A. J. Mordue
Published: April 2011

Barley seedlings were sprayed with azadirachtin or analogues and the resulting crop protection against Schistocerca gregaria was examined. Any change of the parent azadirachtin molecule resulted in less effective insect control and hence more crop damage. Crop protection by azadirachtin and dihydroazadirachtin resulted from both antifeedancy and toxicity, 3‐tigloylazadirachtol was more effective by direct toxicity after significant ingestion and bromoethoxyazadirachtin showed extremely low antifeedant and insecticidal properties. S. gregaria was shown to be very sensitive to change in the azadirachtin molecule.
Effect of age on the responsiveness of peripheral chemosensory sensilla of the turnip root fly (Delia floralis)
Authors: Blaney W. M. , Simmonds M. S. J.
Published: April 2011

The effect of insect age on the neural responsiveness of gustatory sensilla was investigated. Electrophysiological recordings were obtained from type A and type D sensilla on the pro‐ and meso‐thoracic tarsi, and from sensilla on the labellum of the turnip root fly, Delia floralis (Fallen) in response to potassium chloride, sucrose and sinigrin. The age of the fly did have an effect on the numbers of sensilla responding to the test stimuli and on the magnitude of the response, but there was no consistent pattern in these effects among sensilla. The labellar sensilla were more responsive to sucrose than the tarsal sensilla and the proportion of flies whose labellar sensilla responded to sucrose was initially low, but increased after day 2 of adult life. In contrast, the number of flies whose tarsal sensilla responded to stimulation with sucrose was initially high and decreased as the flies aged. There was a similar decline in the proportion of tarsal sensilla responding to potassium chloride. Neither the proportion of flies whose tarsal sensilla responded to sinigrin nor the magnitude of the response was influenced by the age of the fly. These finding are discussed in relation to the feeding and host selection behaviour of the fly.
Selection of Azolla forms resistant to the water lily aphid, Rhopalosiphum nymphaeaeLife history of Rhopalosiphum nymphaeae
Authors: Hance Th. , Nibelle D. , Lebrun Ph. , van Impe G. , van Hove C.
Published: April 2011

The water lily aphid Rhopalosiphum nymphaeae (L.) (Homoptera: Aphididae) is one of the potential pests of the genus Azolla Lam., an agronomically important aquatic fern used as green manure and as fodder. In this paper its life and fertility table was established by observing 70 virginoparous females individually from birth to death on Azolla microphylla Kaulf. under constant abiotic conditions. A rather short average development time of 6.1 days was observed. The maximum length of survival recorded was 24 days, and a linear relationship was found between age and survival. The fecundity averaged 36.8 larvae/female, but this appeared to be an age‐specific parameter. Life table computation showed a high intrinsic rate of increase (0.315 days−1), meaning that theoretical populations could double every 2.2 days.

Les fougères aquatiques du genre Azolla présentent un grand intérêt en agriculture tropicale et subtropicale, comme engrais vert et comme source de nourriture. Le puceron Rhopalosiphum nymphaeae (L.) est un des insectes déprédateurs susceptibles d'affecter considérablement la productivité d'Azolla Lam.

Le but de cette étude était de déterminer les paramètres démographiques et d'établir la table de survie de R. nymphaeae. Pour ce faire, 70 femelles virginopares ont été observées depuis leur naissance jusqu'à leur mort sur Azolla microphylla (souche 69 MI).

Le temps de développement moyen enregistré est de 6,1 jour. La survie maximum est de 24 jours et une relation linéaire entre l'âge et le taux de survie a été mise en évidence. La fécondité moyenne totalise 36,8 larves par femelle mais la fécondité journalière montre une évolution clairement âge‐spécifique. Le calcul des paramètres de la table de survie a mis en évidence le haut taux d'accroissement intrinsèque (0,315 par jours), ce qui signifie qu'une population dont la distribution d'âge serait constante dans le temps verrait son effectif doubler tous les 2,2 jours.
Selection of Azolla forms resistant to the water lily aphid, Rhopalosiphum nymphaeaeSusceptibility of Azolla forms to Rhopalosiphum nymphaeae
Authors: Hance Th. , Nibelle D. , Lebrun Ph. , van Impe G. , van Hove C.
Published: April 2011

The least expensive method for controlling the water lily aphid, Rhopalosiphum nymphaeae (Homoptera: Aphididae), would be to select a more resistant variety of Azolla. Therefore the susceptibility of 6 species of Azolla totalling 12 forms, was analysed by the use of aphid survival and cumulative fecundity. For each form, a minimum of 50 to 140 virginoparous females were followed individually from birth to death. Six forms of three species appeared to be totally resistant, as a mortality rate of 100% was recorded after 4 days; thus insects were unable to reach adulthood. For one form, adults were obtained but died within 11 days and fecundity was poor. The other five forms were more susceptible, and significant differences were found in the total number of offspring after one generation.

These results show differences in susceptibility between different forms of Azolla, and thus strongly support the possibility of cultivating more resistant varieties.

Le puceron Rhopalosiphum nymphaeae (L.) peut causer des dégâts importants dans les cultures de la fougère aquatique Azolla. Aussi, dans le but de contrôler ce puceron au moindre coût et sans effets secondaires sur l'environnement, l'étude de la sensibilité différentielle de 12 formes appartenant à 6 espèces d'Azolla a été entreprise. Pour chaque forme de la fougère, de 50 à 140 femelles virginopares du puceron ont été observées durant toute leur vie.

Sept formes sont apparues comme totalement résistantes. Cent pourcents de mortalité y ont été observés après 4 jours d'expérience. Pour une forme, des pucerons adultes ont été obtenus mais leur fécondité s'est avérée insuffisante pour compenser les 100% de mortalité observés après 11 jours d'expérience. Les cinq autres formes se sont montrées plus sensibles; dans ce cas, des différences entre les effectifs obtenus après une génération ont permis d'établir un classement de sensibilité variétale.

L'existence de ces différences de sensibilité au puceron permet d'envisager la sélection de formes plus résistantes et leur utilisation en conditions de cultures.
Uscana lariophaga, egg parasitoid of bruchid beetle storage pests of cowpea in West Africa: the effect of temperature and humidity
Authors: van Huis A. , Arendse P. W. , Schilthuizen M. , Wiegers P. P. , Heering H. , Hulshof M. , Kaashoek N. K.
Published: April 2011

The stored‐product bruchid pests, Callosobruchus maculatus (Fabricius) and Bruchidius atrolineatus (Pic) cause considerable production losses in cowpea in West Africa. Uscana lariophaga Steffan parasitizes the eggs of the bruchids both in the field and in storage. As chemical control of bruchids in traditional granaries is not appropriate for poor farmers, enhancement of the efficacy of the parasitoid by environmental manipulation has been investigated. The effect of temperature on the capacity of U. lariophaga to parasitize eggs has been studied at eleven constant and three fluctuating temperatures within the range 10 to 45 °C. Longevity of the female wasp decreased with increasing temperature. The rate of development increased linearly at temperatures from 17.5 to 35 °C, but decreased from 35 to 40 °C. Mortality of the developing wasp remained below 20% from 20 to 37.5 °C, but outside this range, mortality reached 100% at 15 and at 42.5 °C. Most parasitization occurred at temperatures of 25 and 30 °C. Sex ratio (percentage females) increased with temperature in the high temperature range. The intrinsic rate of increase (rm) for U. lariophaga was highest in the temperature range from 30 to 37.5 °C and was higher than that of C. maculatus at all temperatures. While the rm value of C. maculatus did not vary much at temperatures from 25 to 35 °C, the rm value of the wasp doubled. Relative humidity did not effect longevity, egg‐laying capacity, mortality, development time and sex ratio of the wasps with C. maculatus as host. However, with B. atrolineatus as the host, development time and mortality increased at lower relative humidity levels. The results indicate that temperature is the major regulating factor on the parasitoid. As the type of storage structure and its location (sun or shade) affects the temperature inside the store, ways are being investigated of manipulating the storage environment through temperature regulation to increase the impact of the parasitoid.
Physiological resistance and behavioral avoidance responses to residues of four pesticides by six spider mite populations
Authors: Suiter K. A. , Gould F.
Published: April 2011

Six twospotted spider mite populations were assayed for their levels of physiological resistance and behavioral avoidance to residues of four synthetic pesticides. Mortality could not be estimated for bifenthrin and fenvalerate (synthetic pyrethroids) as mites effectively avoided treated surfaces, however significant between‐population differences in mortality were detected for chlordimeform and cyhexatin. Considerable variation in walkoff and spindown behavioral response to sub‐lethal doses of pesticides was observed among populations within compounds, and within populations among compounds. Within‐compound walkoff and spindown behavioral response varied among all mite populations. Few significant between‐compound correlations were significant, indicating that spider mites responded differently to the four pesticides. The hypothesis that physiological resistance is negatively correlated with behavioral avoidance was tested. Of the four possible negative correlations between physiological resistance and behavioral avoidance for chlordimeform and cyhexatin, only the correlation between cyhexatin‐induced mortality and spindown response was significant. Comparisons of physiological resistance and behavioral avoidance of chlordimeform and cyhexatin by specific pairs of populations did not consistently find these two characters to be related. In a related experiment, the magnitude and direction of the correlation between physiological resistance and behavioral avoidance following selection for increased physiological tolerance to cyhexatin was compared in a highly resistant and a susceptible population of the twospotted spider mite. Mortality in the susceptible population at 2 ppm cyhexatin was similar to mortality in the resistant population at 250 ppm after 72 h exposure (ca. 12%). However, at these concentrations, the resistant population exhibited much higher avoidance of the compound through walkoff response.
Regulation of Helicoverpa zea larval behavior by the parasitoid Eucelatoria bryani
Authors: Reitz Stuart R. , Nettles William C.
Published: April 2011

The parasitoid Eucelatoria bryani Sabrosky regulates the larval behavior of its host Helicoverpa zea (Boddie). Parasitized third, fourth and fifth instars burrow into the soil 0.7–3.4 days earlier than unparasitized larvae that normally enter the soil to pupate at the end of the fifth and final larval instar. Parasitized third instars molt once then burrow as fourth instars, one instar earlier than normal. When E. bryani pupariated on the soil surface in the field, none survived to the adult stage. However, E. bryani adults emerged from 49.2% of hosts that had burrowed into the soil. By accelerating the timing of H. zea burrowing behavior and causing host larvae to enter the soil before death, E. bryani ensures its pupariation in an environment with improved protection against natural enemies and lethal temperatures.
Investigations of the host feeding preferences of Sitona weevils found commonly on white clover (Trifolium repens) in the UK
Authors: Murray P.J. , Clements R.O.
Published: April 2011

A series of laboratory and field studies were done to evaluate a range of leguminous plant species for their feeding potential by adult weevils of the genus Sitona Germar. (Coleoptera: Curculionidae). Three species of Sitona, S. lineatus L., S. flavescens Marsh. and S. hispidulus F. all of which are found commonly on white clover (Trifolium repens L.) in the UK were offered a range of 11 legume species, T. repens (white clover, cv. Olwen), T. pratense L. (red clover, cv. Marcom), T. fragiferum L. (strawberry clover, cv. Palestine), T. hybridum L. (hybrid clover, cv. Tetra), T. incarnatum L (crimson clover), T. dubium Sibth. (lesser yellow trefoil), Lotus corniculatus L. (birdsfoot‐trefoil, cv. Leo), L. uliginosus Schkuhr. (large birdsfoot‐trefoil), Melilotus alba Desr. (white melilot), Medicago sativa L. (lucerne, cv. Europe) and M. lupulina L. (black medick) in two laboratory experiments. The weevils were offered a choice of these legumes in one experiment whilst in the other they did not have a choice of food material. These legumes were also sown in the field and a number of measurements of damage, together with counts of Sitona spp., were made. In the laboratory S. lineatus and S. hispidulus favoured some of the legumes to a greater or lesser extent than white clover. S. flavescens was more restricted in its feeding than the other two weevil species. In the field study S. lineatus invaded the experimental area quickly and tended to favour Medicago spp. and Melilotus spp. Later in the year S. flavescens dominated the sitona fauna on the experiment, with the exception of aggregations of S. lineatus on M. sativa and M. alba. In a separate screen of 5 varieties of white clover (cvs Donna, Menna, Kersey, Olwen and Grasslands Huia), cv. Olwen appeared to be the most susceptible to sitona attack.
Interactions between panicle size, insect density, and environment for genotypic resistance in sorghum to head bug, Calocoris angustatus
Authors: Sharma H. C. , Lopez V. F.
Published: April 2011

Studies were undertaken on interactions between panicle size, insect density, host plant, and the environment for sorghum head bug, Calocoris angustatus Lethiery on five sorghum genotypes in terms of bug population increase, grain damage and loss in grain mass across four panicle sizes (5, 10 or 20 branches/panicle and whole panicle), and three infestation levels (5, 10 and 15 pairs of bugs/panicle). Head bug numbers increased and grain damage decreased with an increase in panicle size in the head bug susceptible cultivars, CSH 1 and CSH 5. However, the increase in bug numbers or decrease in grain damage was not significant in head bug resistant genotypes, IS 17610 and IS 17645. Head bug numbers increased with an increase in infestation level in CSH 1 and CSH 5, however, such an increase was not substantial in IS 17610 and IS 17645. Grain damage was significantly lower in IS 17610 and IS 17645 compared with CSH 1 and CSH 5 across infestation levels. Head bug population increased at a greater rate during the rainy season compared with the dry season. Panicle size and infestation levels accounted for greater variation in grain damage and percentage loss in grain mass during the rainy season than in the dry season. To identify reliable sources of resistance to insects, it is important to study insect host plant‐interactions across panicle sizes (levels of food availability), infestation levels and season
Geographical variation in habitat choice and host suitability in the parasitoid Asobara rufescens
Authors: Kraaijeveld Alex R. , Voet Steven , van Alphen Jacques J. M.
Published: April 2011

In the Netherlands, Asobara rufescens (Förster) (Hymenoptera: Braconidae) is a parasitoid of drosophilid larvae in decaying plant material. In several places in the Mediterranean, parasitoids looking very similar to A. rufescens were collected on fermenting substrates. A hybridization experiment showed that the parasitoids were indeed A. rufescens. In an olfactometer Portuguese A. rufescens do not have a preference for either the odour of yeast or decaying leaves, while their Dutch conspecifics prefer the odour of decaying leaves. The survival probability of Portuguese A. rufescens in Drosophila melanogaster Meigen (Diptera: Drosophilidae), a species typical for fermenting substrates, is much higher than the survival probability of Dutch A. rufescens in this host species.

It is hypothesized that decaying plant material may be unsuitable for drosophilid larvae during part of the year in the Mediterranean, forcing A. rufescens there to broaden its microhabitat choice. The use of fermenting substrates brings A. rufescens in contact with its sibling A. tabida Nees, a species typical for fermenting substrates in most of Europe. Portuguese A. rufescens appear to be genetically isolated from A. tabida. In the Netherlands, where the two species occupy different microhabitats, there is only a premating barrier.
Effects of the ecdysteroid agonists RH 5849 an RH 5992, alone and in combination with a juvenile hormone analogue, pyriproxyfen, on larvae ofSpodoptera exigua
Authors: Smagghe Guy , Degheele Danny
Published: April 2011

Biological activity assays with RH 5849 and RH 5992 indicated that both compounds affected growth and development of last‐instar larvae ofSpodoptera exigua(Hübner) (Lepidoptera: Noctuidae) in a dose‐dependent manner. Within the first 24 h after treatment by continuously offering leaves dipped in a water solution of ≥ 50 mg/1 RH 5849 and ≥ 0.5 mg/1 RH 5992, symptoms of a prematurely induced larval moult and head capsule apolysis were visible. Intoxicated larvae died shortly afterwards, showing signs of unsuccessful ecdysis. LC50‐values of RH 5849 and RH 5992 for fifth‐instarS. exigualarvae were 110 and 2.5 mg/l, respectively. Pyriproxyfen alone affected the larval stage and disturbed normal metamorphosis. One supernumerary larval instar occurred occasionally. LC50‐value for pyriproxyfen was 1.7 mg/l. Larvae simultaneously treated with RH 5849 or RH 5992 and pyriproxyfen, continued to grow until they attained a size and weight about 2–3 times that of the controls. This growth was accompanied by at least one and sometimes two supernumerary moults.

Concerning thein vivoimaginal wing disc growth and development, only in larvae treated with 10 and 50 mg/l RH 5849 or 0.5 mg/l RH 5992, tracheole migration was observed earlier than in the controls. When applying 300 mg/l RH 5849 or 3–7 mg/l RH 5992, the discs remained small and no signs of tracheole migration were observed. In larvae simultaneously treated with RH 5849 or RH 5992 and pyriproxyfen, tracheole migration was not prematurely induced and a pupal cuticle was produced in the discs of larvae, undergoing a supernumerary moult. No clear signs of evagination were observed.
Predatory behavior of a seed‐eating ant: Brachyponera senaarensis
Authors: Lachaud Jean‐Paul , Déjean Alain
Published: April 2011

The great flexibility of the feeding strategies exhibited by the ponerine ant Brachyponera senaarensis (Mayr) allows it to exploit either seeds or animal prey items as food resources. Predation is generally limited to small prey and is very similar to scavenging behavior. In laboratory conditions, the predatory behavior of B. senaarensis is not different in structure from that known in other carnivorous ants species. The workers forage individually and return to the nest using a series of cues involving light, a chemical graduated marking system near the nest entrance, and memory. During nest‐moving, recruitment by tandem running was observed. However, in colonies where the food supply is regular, workers that discover food do not recruit nestmates, but make repeated trips between the nest and the food source. On the contrary, in starved colonies, the introduction of prey may produce a massive exit of foragers, corresponding to a primitive form of mass recruitment similar to that observed in some other ant species.
Age effects on the insemination rate of Anopheles gambiae s.l. in the laboratory
Authors: Verhoek B. A. , Takken W.
Published: April 2011

Accepted: December 30, 1993

Age effects on the insemination rate of the Galisua strain of Anopheles gambiae s.s. (Diptera: Culicidae) and of the Nyanza strain of An. arabiensis were investigated in the laboratory. Batches of 7‐day old males and females were kept together for 24 h with batches of mosquitoes of the opposite sex of ages ranging from 1–7 days. Males and females were also kept together continuously from emergence. The effect of increasing male/female ratios on the insemination rate was investigated as well. The insemination rate of An. arabiensis in the laboratory (96%) was similar to that found in nature, whereas that of our strain of An. gambiae s.s. was consistently low (maximum 72%), particularly after females had been together with males for a 24 h period only. The optimum age for insemination was 7 days for males and females of both species. The insemination rate of our strain of An. arabiensis was significantly higher at all ages than that of our strain of An. gambiae s.s. The latter strain became inseminated at the earliest when 4 days old. An increase in the male/female ratio significantly enhanced the insemination rate in both strains. It was found that motility of spermatozoa inside the spermatheca, once in contact with saline, could be used as a marker for the approximate time of insemination. It is concluded that the relatively low insemination rate of the Galisua strain of An. gambiae s.s. is unlikely to be caused by the rearing conditions. Other factors that may be responsible are discussed.
Effets d'un régulateur de croissance d'insectes, le fénoxycarbe, sur la diapause du psylle du poirier Cacopsylla pyri
Authors: Lyoussoufi A. , Gadenne C. , Rieux R. , d'Arcier F. Faivre
Published: April 2011

Effects of an insect growth regulator, fenoxycarb, on the diapause of the pear psylla, Cacopsylla pyri Under natural conditions, winter‐form females undergo a reproductive diapause. Topical application on adults and treatment of young pear foliage with fenoxycarb show that this mimic of juvenile hormone (JH) accelerates ovarian maturation of winter‐form females, leading to a rapid breakdown of diapause. Treatment of males increases the mating rate of non‐treated females. The physiologically mature winter‐form males exhibit a behavioural arrest which can be eliminated by this insect growth regulator. Mating thus depends more on the ‘maturity of sexual behaviour’ of males than on the physiological maturity of females.

Les femelles de forme hivernale de Cacopsylla pyri (L.) présentent dans les conditions naturelles une diapause reproductrice. L'application topique sur les adultes et foliaire sur jeunes poiriers du fénoxycarbe, montrent que ce mimétique de l'hormone juvénile (JH), accélère la maturation ovarienne et permet une levée rapide de la diapause. Le traitement des mâles augmente le taux de fécondation chez les femelles non traitées. Les mâles, très tôt physiologiquement mûrs, présentent un blocage comportemental qui est levé par ce régulateur de croissance. L'accouplement dépendrait ainsi plus de ‘la maturité du comportement sexuel’ des mâles que de la maturité physiologique des femelles.
Aggregation patterns of Bemisia tabaci in response to insecticide applications
Authors: Athayde Tonhasca Jr.  , Palumbo John C. , Byrne David N.
Published: April 2011

We measured the effect of insecticide applications on the distribution patterns of the sweet potato whitefly, Bemisia tabaci (Gennadius), in fields of cantaloupe, Cucumis melo L., in Yuma, Arizona. Whitefly infestations were measured by counts of adults, eggs, first to mid/fourth instars, and late‐fourth instars (‘red‐eyed’) nymphs. Adults were sampled from the entire leaf, and immature stages were counted in a 1‐cm2 area of a leaf. The indices b (Power Law), β (Patchiness regression) and Id (Morisita) indicated that all life stages were aggregated, but results for the three indices were not similar for determining the relative aggregation levels between treatments. In general, indices β and Id indicated higher aggregation in insecticide‐treated fields, whereas b had mixed results. The Morisita index was sensitive to a few unusually high means among a series of low densities in the treatment plots, what could be attributed to refuges due to failure in the insecticide applications. Despite the usefulness of the Power Law and the Patchiness regression for describing the relationship between spatial or temporal variability and mean densities, we suggest that Id is more appropriate for expression of spatial distribution because it is based on a precise definition of aggregation.
An antimony‐silver/silver chloride electrode system for measuring pH in insect gut contents
Authors: Biggs David R. , Greenway Robert M. , McGregor Peter G.
Published: April 2011

An electrode system consisting of a cast antimony rod with a silver chloride‐coated wire as a reference electrode has been developed to measure pH in insect gut contents. The electrode works well with buffer volumes down to 0.1 μl. Response to pH is linear between pH 4 and 11 and equates to a change of 52.3 mV per pH unit at 18–20 °C. Electrical resistance is low (0.25 MΩ), so the electrode can be used with low‐impedance meters and does not require shielding from induced currents. Its useful range lies between redox potentials −330 mV (pH 7) and +297 mV to 350 mV, corresponding to a pe + pH range of 1.4 to about 10.8. This covers reported gut pH values for most insects so far examined. Consequently the electrode is suitable for measuring pH of gut contents from many insects that are too small to be analysed with current commercial electrodes.
Disrupting spring colonization of Colorado potato beetle to nonrotated potato fields
Authors: Weber D. C. , Ferro D. N. , Buonaccorsi J. , Hazzard R. V.
Published: April 2011

Overwintering Colorado potato beetles (Leptinotarsa decemlineata (Say)) were concentrated primarily within woody borders, and mortality was lower in borders than in potato fields. After overwintering, only 15–44% of live beetles were in the potato fields. In experiments with small plots, colonization of fields from woody borders was reduced ∼ 60% by a trap crop, either treated with adulticide or with beetles collected daily. Such trap crops, or simply pitfall traps to prevent colonization from woody borders, could significantly reduce early‐season adult numbers and subsequent larval populations. However, success is dependent on the local densities of overwintered beetles, and the prevalence of arrestment behavior in the case of trap crops.
Stabilité du polymorphisme enzymatique dans les populations d'un Lépidoptère migrant, Agrotis ipsilon
Authors: Buès R. , Freuler J. , Toubon J. F. , Gerber Susanna , Poitout S.
Published: April 2011

Homogeneous population structure in a migrant Lepidoptera, Agrotis ipsilon.

Light trapping of Agrotis ipsilon (Lepidoptera, Noctuidae) on various passes of the Alps and Pyrénées exhibited wide range movements between overwintering and aestivation areas. Electrophoretic analysis of samples taken in the Cantons of Vaud and Tessin (Switzerland), in the Rhône Delta (Southern France), and on passes of the Alps and Pyrénées, showed a great temporal and spatial homogeneity of allele frequencies (Fst values ranging from 0.002 to 0.013, and genetic distances from 0 to 0.004). These results support the hypothesis of a high level of gene flow. However, the occurrence during some years of high Fis values, might be explained by mixtures of populations that had undergone selection or went through a bottle‐neck.
Effect of constant temperatures on development of the walnut husk fly, Rhagoletis completa
Authors: Kasana Abdulmajid , AliNiazee M. T.
Published: April 2011

The developmental rates of various life stages of Rhagoletis completa Cresson (Diptera: Tephritidae) were determined in the laboratory at seven different constant temperatures: 8, 12, 16, 20, 24, 28, and 32 ± 1°C, RH 80 ± 10%, photoperiod L16:D8. Preoviposition developmental rate was fastest at 28°C (10 ± 1 days, mean ± SD) and slowest at 12°C (26 ± 1 days). About 83% of the females deposited eggs at 20 and 24°C and only 25% oviposited at 32°C. Females laid the highest number of eggs at 24°C and the lowest at 8°C. Egg development increased with increasing temperatures up to 28°C, then declined. The fastest egg development was noticed at 28°C (55 ± 1 h) and slowest at 8°C (389 ± 2 h). Over 90% egg hatch was observed at temperatures between 12 and 32°C, but decreased to 73% at 8°C. Larval development was fastest also at 28°C (20 ± 0.2 days). Over 65% pupation was recorded at 20 and 24°C, but decreased to 15% at 32°C and 12% at 8°C. Pupal development was most rapid at 24°C (53 ± 1 days) and slowest at 8°C (162 ± 2 days). More than 70% of adult emergence was noticed in treatments between 16 and 24°C but decreased to 20% at 8°C. Based on a linear regression model of temperature‐development rate relationship, the lower developmental thresholds were determined to be 6.6, 5.3, 2.9, and 5°C for preoviposition, egg, larval, and pupal stages, respectively. Based on a non‐linear developmental rate model, the upper developmental thresholds were 34°C for preoviposition, egg, and larval stages and 30°C for pupal stage.
Monophagy in a polyphagous grasshopper, Schistocerca shoshone
Authors: Sword G. A. , Chapman R. F.
Published: April 2011

The feeding behavior of different populations of the grasshopper, Schistocerca shoshone, was investigated in the southwestern United States. Insects from three riparian populations, with a broad spectrum of plants available to them, tended to eat plants roughly in relation to their availability except that broad‐leaved herbaceous plants were avoided. Insects from a desert population in a plantation of Simmondsia fed exclusively on that plant, as did those from another population in the Tucson mountains, despite the availability of a range of other plants. Insects from a third desert population, near Portal, fed mainly on Prosopis, the dominant woody plant. In detailed behavioral experiments in the laboratory, insects from Tucson mountains readily accepted Simmondsia, and less readily accepted Prosopis. Three other common woody plants from the habitat were generally rejected without feeding. Insects from Portal accepted Prosopis and Simmondsia with approximately equal readiness. Breeding experiments suggested that the differences between the plantation insects and those from Portal was genetic and not induced by experience. The insects from both populations were potentially polyphagous and ate a wide range of plants in the laboratory if given no alternative.
Apple maggot fly response to red sphere traps in relation to fly age and experience
Authors: Duan Jian Jun , Prokopy Ronald J.
Published: April 2011

Responses of the apple maggot fly, Rhagoletis pomonella (Walsh), to 8 cm red sticky sphere traps, baited with the synthetic fruit odor butyl hexanoate, were investigated in field‐caged apple trees containing green or red Gravenstein apples. Trap capture rate and the probability of oviposition in apples before capture generally increased with female age and number of mature eggs in ovaries. Two days of pre‐test exposure of mature females to red hawthorns, green Red Delicious apples or green Gravenstein apples had no significant effect on the likelihood of a fly finding a red sphere. However, before capture on a sphere or departing a tree, hawthorn‐exposed females found significantly fewer apples and laid significantly fewer eggs than females exposed to Gravenstein apples. Variation in duration of pre‐test exposure (1–4 days) of flies to Gravenstein apples had no detectable influence on female response to apples or to a red sphere in a test tree. The relevance of these findings to effectiveness of sphere traps for R. pomonella control in commercial orchards is discussed.
Crowding inhibits pupation in Tribolium freemani: contact chemical and mechanical stimuli are involved
Authors: Kotaki Toyomi , Fujii Hiroshi
Published: April 2011

Pupation of Tribolium freemani larvae was strongly inhibited by crowding. When such larvae were transferred to regimes with various levels of food quantity (1, 2 and 3 g) and rearing density (1 to 5 larvae/g food), the percentage of pupation observed within 10 days after transfer increased as the rearing density decreased, regardless of the amount of food medium. Co‐rearing of single T. freemani larvae with Tenebrio molitor larvae or mechanical stimulation with a shaker or rotator also exerted a pupation‐inhibiting effect. Larvae confined individually in a wire cage held in vials containing a group of larvae underwent metamorphosis as did isolated ones. These results suggest that a tactile stimulus is important in manifestation of the crowding effect. Freshly killed larvae had some crowding effect on isolated larvae, but this effect was significantly reduced when the dead larvae had been washed with hexane. Hexane extracts of larvae delayed the time of pupation in isolated larvae in a dose‐dependent manner. Therefore, a substance(s) on the body surface of larvae may be involved in the crowding effect.