bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses of Mamestra suasa male moths to synthetic pheromone compounds in a wind tunnel
Authors: Frérot Brigitte , Lucas Philippe , Rochat Didier
Published: April 2011

The upwind flight and landing responses of male Mamestra suasa (Den. & Schiff.) (Lepidoptera; Noctuidae) to various synthetic chemicals were studied in a wind tunnel. Amixture of (Z)‐11‐hexadecenyl acetate (Z11–16:Ac) and (Z)‐11‐hexadecenal (Z11–16:Ald) elicited upwind flight responses past the midpoint of the wind tunnel, and both components were necessary for landing of the males to occur at the pheromone source point. The best response to the mixtures tested was to a ratio 100:1 (ng) of Z11–16:Ac and Z11–16:Ald (blend B).

The addition of (Z)‐9‐tetradecenyl acetate (Z9–14:Ac) (10 ng) to blend B resulted in a significant decrease of upwind flight and landing responses. The inhibitory effect of this chemical when it is mixed with blend B, and the presence of a specific receptor for this compound in sensilla trichodea of male M. suasa, suggest that Z9–14: Ac is involved in the chemical communication between M. suasa and other sympatric species. The addition of (Z)‐11‐hexadecenol (Z11–16: OH) (1 or 10 ng) to blend B had no effect on male upwind flight and landing responses. This compound does not seem to be involved in the chemical communication of this species.

Etude en tunnel de vol des réponses des mâles de Mamestra suasa à des composés phéromonaux de synthèse.

L'observation et la comptabilisation des vols orientés et des atterrissages des mâles de Mamestra suasa (Den. & Schiff.) (Lepidoptera; Noctuidae) sur une source de phéromone de synthèse ont mis en évidence un mélange attractif appelé mélange B et constitué par 100 ng de Z11–16: Ac et 1 ng de Z11–16: Ald. L'attraction et l'atterrissage sont sous la dépendance du mélange de ces 2 composés. Les variations de leurs proportions relatives affectent les différentes phases du comportement de vol des mâles.

L'addition de 10 ng d'acétoxy‐1 tetradécène‐9 Z (Z9–14: Ac) diminue significativement les proportions de vols orientés et d'atterrissages par rapport aux réponses obtenues avec le mélange B seul. L'effet inhibiteur de cette molécule sur l'attractivité du mélange B et la présence chez M. suasa d'un récepteur spécialisé dans la perception de ce composé suggèrent que le Z9–14: Ac est impliqué dans la communication chimique entre M. suasa et d'autres espèces sympatriques. L'addition d'hexadécènol‐11 Z (Z11–16:OH) au mélange B à la dose de 1 ou 10 ng ne modifie pas les réponses des mâles. Ce composé ne semble pas impliqué dans la communication chimique chez M. suasa.
Attraction of the cabbage looper to host plants and host plant odor in the laboratory
Authors: Landolt Peter J.
Published: April 2011

In a laboratory flight tunnel, mated female, unmated female, and male adult cabbage loopers, Trichoplusia ni (Hübner), exhibited chemically mediated anemotaxis (attraction) in response to intact potted cabbage plants (Brassica oleracea L.), leading to contact with the plant. Similar attraction responses were also observed by mated females to potted soybean (Glycine max (L.)), tomato (Lycopersicon esculentum Miller), and celery (Apium graveolens L.) plants in noncompetitive comparisons. Mated females, unmated females, and males flew to cabbage plants throughout the scotophase. Response rates for mated females were higher than for unmated females and males. Mated female cabbage loopers were attracted by odors of cabbage, soybean, tomato, or celery piped into a flight tunnel from single plants held in glass jars and not to odors of the non‐host plant Setcreasea purpurea, or to humidified air. They were also attracted to water washings of cabbage at dosages of 0.4 to 2.0 gram equivalents, when presented on cotton dental wicks in the flight tunnel.

Attraction au laboratoire de Trichoplusia ni par des plantes hôtes ou par l'odeur de plantes‐hôtes

Dans un tunnel de vol, des femelles vierges ou inséminées et des mâles de T. ni Hübner, réagissent par une anémotaxie chimique (attraction) à des plantes entières de Brassica oleracea L., ce qui a entraîné le contact avec le végétal. Avec Glycine max (L), Lycopersicon esculentum (Miller) et Apium graveolens (L), des attractions du même type ont été observées chez des femelles inséminées, mais en absence de compétition entre les plantes. Les femelles vierges et inséminées ainsi que les mâles volent vers le chou pendant la scotophase. Le taux de réactions des femelles inséminées a été le plus élevé. Dans un tunnel de vol, ces mêmes femelles étaient attirées par les odeurs de plantes isolées de chou, soja, tomate et céleri, mais non par celle de la plante non‐hôte, Setcreasea purpurea, ou par de l'air humide. Dans le tunnel de vol, elles ont été attirées aussi par des mèches de coton dentaire imprégnées d'eau de lavage de chou aux concentrations de 0,4 à 2,0 équivalents grammes.
The role of availability of food and water to the adult Epiphyas postvittana, the light brown apple moth, in its reproductive performance
Authors: Gu H. , Danthanarayana W.
Published: April 2011

Female Epiphyas postvittana (Lepidoptera, Tortricidae) moths were able to lay fertile eggs without feeding, but they require water to achieve their full reproductive potential. Fecundity of moths given water from emergence was not different from that of moths fed with 30% honey solution. Deprivation of feeding during the early stage (up to three days after emergence) showed no significant decrease in fecundity provided that honey solution was available from the age of four days after emergence. Starved moths laid less than 30% of the number of eggs laid by those fed with honey solution or water. Fecundity was correlated with moth weight at emergence when moths were fed with water or honey solution, but not when no food or water was provided. Moths of both sexes fed on honey solution copulated less frequently, lost body weight at a lower rate and had a greater longevity, compared with those fed with water or nothing. These results are discussed in relation to the reproductive strategy of this species.

Die Bedeutung von Nahrung und Wasser für den Fortpflanzungserfolg der hellbraunen Apfelmotte Epiphyas postvittana

Weibliche Motten der Art Epiphyas postvittana (Lepidoptera, Tortricidae) legten fruchtbare Eier ohne Nahrung aufzunehmen, brauchten jedoch Wasser, um ihr voiles Fortpflanzung – Potential zu erreichen. Fruchtbarkeit von Motten, denen Wasser von der Zeit des Schlüpfens an gegeben wurde, unterschied sich nicht von der Fruchtbarkeit der Motten, die mit einer 30 prozentigen Honiglösung gefüttert wurden. Nahrungsentzug während der frühen Entwicklung (bis zu drei Tagen nach Schlüpfen) führte nicht zu einer Reduktion der Fruchtbarkit, vorausgesetzt dass Honiglösung von einem Alter von vier Tagen nach Schlüpfen angeboten wurde. Hungernde Motten legten weniger als 30% der Eier als mit Honiglösung oder Wasser gefütterte Motten. Fruchtbarkeit war korreliert mit dem Gewicht der Motten zur Zeit des Schlüpfeus, wenn die Motten mit Wasser oder Honiglösung gefüttert wurden, jedoch nicht, wenn weder Nahrung noch Wasser angeboten wurde. Mit Honiglösung gefütterte Motten beiderlei Geschlechts kopulierten weniger häufig, verloren Gewicht langsamer und lebten langer als mit Wasser oder nicht gefütterte Motten. Die Ergebnisse werden diskutiert in Bezug auf die Fortpflanzungsstrategie der Art.
Comparative flight behavior of Diabrotica virgifera virgifera and Diabrotica barberi in the laboratory
Authors: Naranjo Steven E.
Published: April 2011

A tethered flight system was used to characterize and compare the flight behavior of western, Diabrotica virgifera virgifera LeConte (WCR), and northern, Diabrotica barberi (Smith and Lawrence) (NCR), corn rootworms in the laboratory. Distributions of flight durations were skewed towards short flights for both species regardless of sex or age and there was high variability in flight durations and frequency in individual beetles. Flight distributions for WCR were distinctly bimodal, reflecting a dichotomy between short trivial flights and much longer sustained flights. Trivial flight performance did not vary with age but did differ between species. In comparison to WCR, NCR took shorter flights but had a higher frequency of flights over a 23‐h period. Overall, WCR beetles logged substantially more flight time in the same period of time. The proportion of individual WCR undertaking sustained flight was relatively low (<24%) and, for females, declined along with sustained flight durations as a function of age. Periodicity of trivial flight did not differ between the species. In general, flight activity was greatest during early morning and early evening hours. No correlations were found between any feature of flight performance and body size or wing loading ratios.

Comparaison au laboratoire des comportements de vol de Diabrotica virgifera virgifera et D. barberi

Un système de vol captif a été utilisé pour caractériser et comparer au laboratoire les comportements de vol de D. virgifera virgifera et D. barberi. La distribution des durées de vol est nettement biaisée avec la grande majorité des vols durant moins d'une minute quels que soient le sexe et l'âge. Il y a une grande variabilité interindividuelle tant en durée qu'en fréquence de vol. Les distributions des durées de vol en fonction du sexe sont bimodales chez D. virgifera virgifera, mais pas chez D. barberi, ce qui reflète la séparation entre vols brefs ordinaires et long vols prolongés. Les vols brefs ordinaires ne dépendent pas beaucoup de l'âge ou du sexe mais diffèrent suivant l'espèce. D. barberi a eu des vols plus brefs, mais en a effectué plus pendant une période de 23 heures. Au total, D. virgifera virgifera a consacré nettement plus de temps au vol pendant la même période; mais, chez cette espèce la proportion d'individus effectuant des vols soutenus était relativement faible (<24%), avec une diminution de leur nombre avec l'âge chez les femelles; le nombre le plus élevé étant chez les jeunes femelles. La périodicité des vols ordinaires n'a dépendu ni du sexe, ni de l'espèce; l'activité de vol a été en général plus importante tôt le matin et en début de soirée. Aucune corrélation n'a été trouvée entre une quelconque performance de vol et la taille du corps ou la charge alaire.
Xylem ingestion by aphids – a strategy for maintaining water balance
Authors: Spiller N.J. , Koenders L. , Tjallingii W.F.
Published: April 2011

A new waveform, pattern G, detected during recording of electrical penetration graphs (EPG's) from aphids was strongly correlated with uptake from radioactively labelled artificial diets. During pattern G, maxillary stylet tips were located within xylem conductive elements and it was concluded that pattern G is representative of ingestion of xylem sap. Dehydrated aphids showed a higher incidence and greater duration of xylem uptake, suggesting that its occurrence is related to the water balance of the insect.

Ingestion du xylème par les pucerons, – un moyen de maintenir l'équilibre hydrique

Une nouvelle onde, de type G, décelée pendant l'enregistrement des électropénétrogrammes (EPG's) des pucerons est nettement associée à la prise d'aliments marqués radioactivement. Pendant l'onde G, les extrémités des stylets maxillaires sont situées dans les éléments conducteurs du xylème et l'on en conclu que l'onde G représente l'ingestion du contenu du xylème. Les pucerons déshydratés présentent une plus grande fréquence et une durée plus longue d'absorption de xylème, ce qui suggère qu'elle est liée à l'équilibre hydrique de l'insecte.
Azadirachtin: structural requirements for reducing growth and increasing mortality in lepidopterous larvae
Authors: Simmonds M. S. J. , Blaney W. M. , Ley S. V. , Anderson J. C. , Toogood P. L.
Published: April 2011

Spodoptera littoralis, Spodoptera frugiperda and Heliothis virescens were exposed to azadirachtin and 23 other related compounds in three bioassays: oral cannulation, haemolymph injection and topical application. Spodoptera littoralis was susceptible to a larger proportion of the compounds than either of the other species. Overall, azadirachtin, 22,23‐dihydroazadirachtin and 1‐detigloyl‐22,23‐dihydroazadirachtin were the most active compounds. The nature of the substitutes at C‐1 and C‐3 of the decalin ring affects the potency of the compounds, as does the addition of substitutes to C‐22,23. Generally, larvae were less sensitive to compounds when they were topically applied than when they were cannulated into the gut or injected into the haemolymph.

Azadirachtine: contraintes structurales nécessaires pour obtenir la réduction de la croissance et l'augmentation de la mortalité chez les chenilles de lépidoptères

Spodoptera littoralis, S. frugiperda et Heliothis virescens ont été exposés à l'azadirachtine et 23 autres substances voisines dans 3 expériences: canulation orale, injection d'haemolymphe et application topique. S. littoralis est sensible à un plus grand nombre de substances que les 2 autres espèces. De toutes façons, les substances les plus actives ont été l'azadirachtine, la 22,23‐dihydroazadirachtine et la 1‐détigloyl‐22,23‐dihydroazadirachtine. La nature des substitutions en C‐1 et C‐3 de l'anneau décaline modifie la puissance des substances, tout comme les substitutions en C‐22,23. D'une façon générale, les chenilles ont été moins sensibles aux applications topiques qu'aux canulations dans le tube digestif ou aux injections dans l'haemolymphe.
The role of kairomones in prey finding by Diomus sp. and Exochomus sp., two coccinellid predators of the cassava mealybug, Phenacoccus manihoti
Authors: van den Meiracker R. A. F. , Hammond W. N. O. , van Alphen J. J. M.
Published: April 2011

We studied searching behaviour of Diomus sp., a coccinellid predator introduced into Africa as a natural enemy of the cassava mealybug, when searching on cassava leaves, and compared its behaviour with the searching behaviour of Exochomus sp., an African predator of mealybugs (MB's). Female adults of Diomus and Exochomus spent more lime searching on cassava leaves previously infested with cassava MB than on clean cassava leaves, in response to substances produced by MB's (wax and/or honeydew) still present on these leaves as kairomones after removal of the MB's. Both species were also arrested by wax and/or honeydew of the citrus mealybug, Planococcus citri. When offered a choice between kairomones of both MB species only experienced Diomus (reared on cassava MB) showed a clear preference for kairomone of cassava MB. Separate influences of wax and honeydew were tested. Wax from cassava MB was an arrestment stimulus for both coccinellid species. Honeydew produced by cassava MB arrested Exochomus and inexperienced Diomus.

Die Rolle von Kairomonen beim Auffinden der Beute von Diomus und Exochomus sp., zwei coccinellide Raüher der Cassaveschmierlaus

Das Suchverhalten auf Cassaveblätter des coccinelliden Raübers Diomus, eines aus Süd Amerika importierten natürlichen Feindes der Cassaveschmierlaus wurde studiert und verglichen mit dem Suchverhalten eines afrikanischen Räubers von Schmierläusen, Exochomus sp., Weiblichen Adulten von Diomus un Exochomus verwendeten mehr Zeit auf Cassaveblätter wenn diese Blätter vorher mit Cassaveschmierläuse infiziert waren als auf uninfizierte Blätter, und gebrauchten Substanzen (Wachs und/oder Honigtau) die von Schmierläuse produziert wurden und nach der Entfernung der Schmierläuse auf die Blatter zugeblieben waren als Kairomonen.

Beide Arten wurden auch von Wachs und/oder Honigtau der Citrusschmierlaus, Planococcus citri, auf den Blätter arretiert. Wenn die Tiere wahlen könnten zwischen Kairomone der beiden Schmierlaus arten wurden die Kairomonen der Cassaveschmierlaus nur von erfahrenen Diomus–Individuen, die auf Cassaveschmierlaüse aufgezogen wurden, bevorzugt.

Die Einflüsse von Wachs und Honigtau wurden separat geprüft. Wachs von Exuvien der Cassaveschmierlaus ist ein Arretierungsstimulus für beide Räuberarten. Von Cassavescbmierläusen produzierten Honigtau arretierte Exochomus‐ und unerfahrene Diomus‐Individuen.
Proteinases and amylases of larval midgut of Zabrotes subfasciatus reared on cowpea (Vigna unguiculata) seeds
Authors: Lemos F. J. A. , Campos F. A. P. , Silva C. P. , Xavier‐Filho J.
Published: April 2011

Proteinase and amylase activities in larval midguts of the bruchid beetle Zabrotes subfasciatus (Boh.) (Coleoptera: Bruchidae) reared on cowpea (Vigna unguiculata (L.) Walp.) seeds were investigated. We could detect and isolate a proteolytic activity with a pH optimum of 5.5 (on azo‐casein as substrate) which was activated by thiol reagents and inhibited by several compounds reactive against ‐SH groups. None of the plant protein inhibitors of serine proteinases utilized were effective inhibitors of this activity. This activity has characteristics of a cysteine class proteinase. We could also detect and isolate a proteolytic activity with a pH optimum of 3.5 (on hemoglobin as substrate) which was not influenced by activators or inhibitors of cysteine, serine, or metalloproteinases. This activity was totally inhibited by pepstatin, a specific inhibitor of aspartic proteinases. We conclude that this activity is due to an aspartic class proteinase. We found also that the aspartic class proteolytic activity is higher than the cysteine class proteinase activity in the midguts of Z. subfasciatus. This seems to be contrary to what is found in Callosobruchus maculatus (F.) larvae midguts. An amylolytic activity with the charateristics of an α‐amylase was also detected and isolated.

Protéinases et amylases de l'intestin moyen de larves de Zabrotes subfasciatus élevées sur Vigna unguiculata

Les activités protéinase et amylase ont été étudiées sur l'intestin moyen de larves de Zabrotes subfasciatus Boh. (Coléo, Bruchidae), élevées sur graines de Vigna unguiculata Walp. Nous avons pu décelcr et isoler unc activité protéolytique optimale à pH 5,5 (sur substrat d'azo‐caséine) activée par des réactifs thiol et inhibée par plusieurs composés réagissant aux groupements SH. Aucun inhibiteur végétal des sérine‐protéases utilisé n'a inibé efficacement cette activité qui présente les caractéristiques des protéines de la famille des cystéines. Nous avons pu déceler et isoler aussi une activité protéolytique optimale au pH 3,5 (sur hémoglobine comme substrat) qui n'était pas modifiée par les activateurs ou les inhibiteurs de cystéine, de sérine ou de métalloprotéinases. Cette activité était totalement inhibée par la pepstatine, inhibiteur spécifique des protéinases aspartiques. Nous en concluons que l'activité est due à une protéinase de la famille aspartique. Nous avons trouvé aussi que l'activité protéolytique de la famille aspartique était supérieure à l'activité protéinase de la famille cystéine dans l'intestin moyen de Z. subfasciatus. Ceci semble l'inverse de ce qui a été observé dans l'intestin moyen des larves de Callosobruchus maculatus F. (C.P. Silva & al, in litt.). Une activité amylolytique ayant les caractéristiques d'une α‐amylase a aussi été décelée.
Pattern of growth and fat content of somatic and gonadal tissues of virginoparae of the vetch aphid, Megoura viciae
Authors: Brough C. N. , Dixon A. F. G. , Kindlmann P.
Published: April 2011

Throughout the development of virginoparous apterae of the vetch aphid, Megoura viciae, the percentage water content remained constant. Over the period from birth to the onset of reproduction the somatic tissues grew logistically and the gonads exponentially. During development the percentage of the weight of an aphid that consisted of gonads increased. The sigmoidal pattern of growth in weight of an aphid reflects the combined growth patterns of the somatic and gonadal components.

Large adults had proportionally bigger gonads than small adults. The fat (lipid) content of both the soma and gonads increased during development; in the soma up to the adult moult, and the gonads up to the onset of reproduction.

Caractères de la croissance et de la teneur en corps gras des tissus somatiques et de gonades des virginipares de Medoura viciae.

Le pourcentagc en cau reste constant pendant tout le développement des virginipares de Megoura viciae. De la naissance au début de la reproduction, les tissus somatiques croissent logisliquement et les gonades exponentiellement. Le poids relatif des gonades augmente pendant le développement. L'allure sigmoïde de la courbe de croissance reflète la cominaison des types de croissance des tissue somatiques et des gonades.

Les gros adultes ont proportionnellement de plus grosses gonades que les petits. La teneur en corps gras augmente dans le soma et les gonades pendant le développement; dans le soma jusqu'à la mue imaginale, dans les gonades jusqu'au début de la reproduction.
Handling time, prey preference, and functional response for Chrysoperla rufilabris in the laboratory
Authors: Nordlund Donald A. , Morrison R.K.
Published: April 2011

The predaceous larvae of Chrysoperla rufilabris (Burmeister) exhibited some success‐motivated searching, particularly when feeding on Heliothis virescens (F.) eggs, but handling time did not decrease with experience. Handling time for H. virescens larvae was more than twice that for eggs. H. virescens larvae were preferred to cotton aphids (Aphis gossypü (F.)) while aphids were preferred to H. virescens eggs. C. rufilabris larvae exhibited a linear functional response to the three prey types tested, over the prey densities tested.

Temps de manipulation, choix des proies et réactions fonctionnelles de Chrysoperla rufilabris au laboratoire

C. rufilabris (Burmeister) est commun dans des habitats variés de différentes parties des USA. Les larves sont prédatrices et attaquent presque tous les insectes au corps mou. Sa prospection est orientée quand il s'alimente sur des œufs et les premiers stades d'Heliothis virescens F. mais pas lorsqu'il consomme Aphis gossypii F. Le temps de manipulation par C. rufilabris n'est cependant pas modifié par la consommation antérieure de proies ces types. Il dépend du type de proie: il est plus de 2 fois plus long avec les chenilles d'H. virescens qu'avec ses œufs. Les larves de C. rufilabris sont des prédateurs généralistes ayant des préférences lorsqu'elles ont le choix: les chenilles d'H. virescens sont préférées aux pucerons du coton, et ceux‐ci aux œufs de H. virescens. Elles présentent une réaction fonctionnelle linéaire pour tous les types de proies, à toutes les densités examinées.

C. rufilabris constitue un potentiel intéressant pour la lutte biologique avec des interventions inondatrices contre de nombreux insectes nuisibles. Cependant, des mises au point techniques sont nécessaires pour obtenir une production de masse économique et des méthodes de libération dans la nature efficaces.
Effects of natural enemies on the rate of herbivore adaptation to resistant host plants
Authors: Gould F. , Kennedy G.G. , Johnson M.T.
Published: April 2011

The potential of natural enemies to influence the rate of herbivore adaptation to resistance factors in plants is examined using conceptual and mathematical models. Results indicate that natural enemies could increase or decrease the rate of herbivore adaptation. The specific behavioral and physiological effects of a resistance factor on the herbivore, as well as the behavior of the natural enemy, and the population dynamics of the natural enemy/herbivore system are important in assessing the extent to which the natural enemies will affect the rate of herbivore adaptation to a resistance factor. Herbivore adaptation to partial resistance in a host‐plant is generally expected to be slower than adaptation to high levels of resistance, even in the presence of natural enemies, if genetic variance is not limiting.

Influence des ennemis naturels sur le taux d'adaptation d'herbivores à des plantes‐hôtes résistantes

Des modèles conceptuels et mathématiques ont servi à examiner l'influence du potentiel d'ennemis

naturels sur le taux d'adaptation d'herbivores à des facteurs de résistance des plantes. Les résultats montrent que les ennemis naturels peuvent augmenter ou réduire le taux d'adaptation des herbivores. Les effets spécifiques (comportementaux et physiologiques) d'un facteur de résistance sur l'herbivore, aussi bien que le comportement de l'ennemi naturel et la dynamique de population du système ennemi naturel/herbivore permettent de déterminer le niveau de l'effet des ennemis naturels sur le taux d'adaptation de l'herbivore au facteur de résistance. Une adaptation de l'herbivore à une résistance partielle à une plante est généralement envisagée comme plus lente qu'une adaptation à des hauts niveaux de résistance, même en présence d'ennemis naturels, mais il peut y avoir des exceptions.
Polymer webs to prevent virus transmission by aphids in seed potatoes
Authors: Harrewijn P. , den Ouden H. , Piron P.G.M.
Published: April 2011

Electrical registration and visual observation of penetration behaviour combined with ELISA‐technique showed that laboratory‐made webs of synthetic fibers were very promising to protect plants against virus infection by aphids. It was demonstrated that stylet penetration by aphids into potato leaves could be prevented by covering plants with these materials. The recent mass production of polypropylene sealed fiber fleeces and polyethylene nettings have made field experiments possible to determine their effect on aphid probing behaviour and virus transmission.

Field experiments with potatoes showed that one particular fleece completely protected the plants against virus transmission (PVY and PLRV) and with a second fleece and a netting a small proportion of plants were infected. In uncovered plots up to 25% of plants became infected. A seed potato crop covered with polypropylene fleece which is inspected regularly for damage will be fully protected against virus transmission.

Utilisation de toiles de polymères afin d'empêcher la transmission de virus par les pucerons chez les pommes de terres semencières

Des enregistrements électriques et des observations visuelles du comportement de pénétration, combinés avec l'usage de la technique ELISA, ont montré que l'usage de toiles de fibres synthétiques élaborées au laboratoire était très prometteur pour la protection des plantes contre des infections virales transmises par des aphides. On a pu démontrer que la pénétration du stylet dans des feuilles de pomme de terre pouvait être empèchée en couvrant les plantes avec ces matériaux. La production en masse récente de nappes en fibres de polypropylene soudées et de filets de polyethylène a rendu possibles des expériences de terrain pour déterminer leur effet sur le comportement de sondage des pucerons et sur la transmission des virus.

Des essais en plein champ avec des pommes de terre ont montré qu'un type de nappe en particulier protégeait complètement les plantes contre la transmission de virus (PVY en PLRV) et qu'avec un second type de nappe et un filet une petite proportion de plantes était infectée. Dans des parcelles non couvertes la proportion de plantes infectées sx'élevait jusqu'à 25%. Une récolte de pommes de terre semencières couverte d'une nappe de polypropylène régulièrement inspectée afin de remédier aux détériorations éventuelles sera totalement protégée contre la transmission de virus.
A comparison between the amino acid composition of an egg parasitoid wasp and some of its hosts
Authors: Barrett M. , Schmidt J. M.
Published: April 2011

Amino acid compositions of the eggs of five lepidopteran hosts for Trichogramma minutum were compared with each other and with a non‐host species, Rhodnius prolixus, in which T. minutum oviposits but does not develop. Host eggs are quite homogeneous, particularly when compared according to groupings of potentially interconvertible amino acids. Combined mole percent values for glycine, serine and alanine were higher in hosts (27.5–29.2 mole%) than in R. prolixus eggs (21.5 mole%), in bovine serum albumin (14.9%), which has been used as a protein source in artificial diets for T. minutum, or in many of the mixtures used in published diets for this species. Since these three amino acids make up 26.3 mole% of the adult amino acid content of T. minutum, their deficiency in diets could require metabolic compensation detrimental to development.

Adult T. minutum arising from eggs of Manduca sexta, Choristoneura fumiferana, and Sitotroga cerealella are similar in amino acid composition to each other and, in general, to their hosts. Variability appears greater in hosts than in adult wasp composition, suggesting some interconversion of host amino acids to accommodate inflexible nutritional requirements of T. minutum.

In the three host species tested, free amino acids constituted 15.8–19.3% by weight of the amino acid in egg contents. In M. sexta eggs, glycine, serine and alanine together make up 28.4% by weight of the total free amino acid, a much higher proportion than in many published diets. The four free amino acids (isoleucine, leucine, phenylalanine and histidine) reported to be oviposition stimulants in experiments on encapsulated diets are present in sufficient concentrations to induce oviposition in the host species tested and in R. prolixus.

S. cerealella egg contents having approximately 1.8 μg amino acid, yield one or rarely two adult T. minutum (1 μg amino acid/insect). In contrast, M. sexta eggs with 94 μg amino acid each yield an average of 10–12 adults (8.2 μg amino acid/insect). This suggests that small hosts are allocated few eggs which can only develop into small adults because of nutrient supply (parasitoid size in metabolically restricted), whereas much larger hosts are allocated proportionately fewer eggs than the former resulting in larger, and presumably more viable and fecund, adults (parasitoid size is established behaviourally).
The effects of temperature and host density on the development and survival of Copidosoma koehleri
Authors: Horne P. A. , Horne J. A.
Published: April 2011

Developmental rates for Copidosoma koehleri Blanchard (Hymenoptera: Encyrtidae) and its host, Phthorimaea operculella (Zeller), were determined at 10, 15, 23, 27, 29, 32, 34 and 35 °C from host egg to adult. The developmental rates determined for both species showed good fit to mathematical models of insect development. At 15 °C mean emergence of adult C. koehleri was 15 days after P. operculella adults emerged. At 29 °C mean emergence of C. koehleri was only 5 days after that of P. operculella. P. operculella developed at 35 °C, but parasitized larvae, and therefore C. koehleri, did not tolerate temperatures above 32 °C. In the presence of C. koehleri, host survival was low (3%) at low host egg densities, but greater (20%) at higher host densities. Parasitized larvae of P. operculella were less able to compete for food resources, as measured by adult emergence.
A study on mode of antifeedant effects of epilimonol against Leptinotarsa decemlineata
Authors: Liu Yong‐Biao , Alford A. R. , Bentley M. D.
Published: April 2011

Colorado potato beetle, Leptinotarsa decemlineata (Say), neonate larvae and adults were bioassayed with the antifeedant epilimonol. Three‐day exposure of neonate larvae resulted in increasing delays in development (appearance of 4th instars) corresponding to increasing dosages. At a dosage of 20 μg/cm2, development was delayed by about 40% without other detrimental effects. Mouthpart coating of adult beetles with epilimonol emulsion resulted in significant feeding reductions, while injection of epilimonol into the haemolymph of female adults did not elicit significant feeding reduction or oviposition suppression. The results indicated that epilimonol did not elicit significant internal toxicity, and feeding reductions were most likely exerted by action on chemoreceptors on mouthparts or in the preoral cavity.
Rutin: a phagostimulant for the polyphagous acridid Schistocerca americana
Authors: Bernays E. A. , Howard J. J. , Champagne D. , Estesen B. J.
Published: April 2011

Rutin was demonstrated to be a phagostimulant for the grasshopper Schistocerca americana across a very wide concentration range. The effect was not maintained over a period of days if the insects had already ingested a large amount, but when individuals were given different concentrations on disks as supplements to their lettuce diet, they tended to self select a moderate quantity on a daily basis. In long term experiments on food utilization and growth rates using artificial diet, no beneficial effects of rutin could be demonstrated. Ingested rutin was absorbed and some of it deposited in the cuticle. Most was excreted as the aglycone quercetin. The possible functional significance of the phagostimulatory effect is discussed.
Influence of endophyte infection, plant age and harvest interval on Rhopalosiphum padi survival and its relation to quantity of N‐formyl and N‐acetyl loline in tall fescue
Authors: Eichenseer H. , Dahlman D. L. , Bush L. P.
Published: April 2011

Rhopalosiphum padi L. (Homoptera: Aphididae) is sensitive to loline alkaloids present in tall fescue, Festuca arundinacea Shreb., infected with the endophytic fungus, Acremonium coenophialum Morgan‐Jones & Gams. Aphid survival was higher on endophyte‐free plants regardless of plant age after germination or age of regrowth tissue after clipping. Survival of aphids on endophyte‐infected grass was lower on young tissue but increased as plants aged, although it never reached the same level on endophyte‐free plants. Both N‐formyl and N‐acetyl loline increased as uncut or regrowth tissue aged; however, this was influenced by the age of the plant at the initial cut and the clipping frequency. Although even small amounts of loline cause high aphid mortality, the aphids are able to survive on endophyte‐infected plants if the tillers have senescing leaves which contain lower amounts of loline. Preference for senescing leaves may help R. padi avoid plant parts containing high amounts of toxic allelochemicals, thus contributing to higher numbers of aphids on older, endophyte‐infected plants.
>Morphogenesis and cuticular markers during the larval‐pupal transformation of the medfly Ceratitis capitata
Authors: Rabossi A. , Boccaccio G. L. , Wappner P. , Quesada‐Allué L. A.
Published: April 2011

Changes in morphology during early metamorphosis of the medfly, Ceratitis capitata (Wied.) (Tephritidae) were correlated with biochemical differentiation events. Protein profiles were studied both in the 3rd instar larval cuticle further transformed into puparium and the newly synthesized pupal cuticle. Beta‐alanine incorporation into the puparium (0–20 h) correlates with concomitant pigmentation (completed by 16 h) and sclerotization phenomena. This early ‘tannification program seems to be followed by deposition of a layer of substances, probably ecdysial fluid remnants, into the puparium. Their deposition ends approximately at +46 h. Simultaneously, pupal cuticle material starts to be deposited. Synthesis and deposition of the main pupal cuticle protein was detected 48 h after pupariation. At that time, eversion of the pupal head occurs. The definitive profile of pupal cuticle proteins was attained at around +72 h together with the establishment of adult body proportions.
Selection for pesticide resistance in Aphytis
Authors: Javier P. A. , Havron A. , Morallo‐Rejesus B. , Rosen D.
Published: April 2011

Field‐collected populations of Aphytis holoxanthus DeBach (Hymenoptera: Aphelinidae) and of A. lingnanensis Compere were selected for malathion and azinphosmethyl resistance, respectively, utilizing the male selection method.

In preliminary experiments, fertility of virgin females was not significantly lower than that of mated females, and the rate of development of their progeny was similar. Males proved more susceptible to pesticides than females, and among them the sons of virgins were more susceptible than the sons of mated females. Some after‐effects of sublethal exposure to pesticides were noted in both species. A mating ratio of 1 selected male: 2.0–2.5 females was optimal. Cold storage of female pupae proved feasible for synchronizing availability.

Resistance of A. holoxanthus to malathion was not increased by 25 male selection cycles. Resistance of A. lingnanensis to azinphosmethyl, which had already been improved by mass selection, was further increased by 7 cycles of male selection.

The different outcomes of the two projects are discussed in relation to the variability of the original field populations, and the results of male selection are compared with those of mass selection of identical populations.
Explaining differences in flea beetle Phyllotreta cruciferae Goeze densities in simple and mixed broccoli cropping systems as a function of individual behavior
Authors: Garcia M. A. , Altieri M. A.
Published: April 2011

Diversification of habitat has proved to be an efficient way to reduce insect pest levels in agroecosystems. Some general theories used to explain this fact, such as the natural enemies and the resource concentration hypotheses, do not always clearly apply because, in many cases, pest individuals and population response seem controlled by more specific insect‐plant interactions. In non replicated plots, we found substantially lower flea beetle densities in mixed broccoli‐Vicia cropping systems compared to broccoli monoculture. These results were consistent with those from controlled experiments reported in the literature. To investigate if beetle behavior was related to such population reduction, the movement behavior of marked individuals of Phyllotreta cruciferae Goeze released in plots composed solely of broccoli plants and of broccoli mixed with Vicia faba or Vicia sativa plants, was followed and analyzed. The mean tenure time of beetles was longer in simple than in mixed cultures. Also, more beetles tended to fly out and leave mixed cultures compared to monoculture. This resulted in faster reduction of artificially introduced flea beetle populations in the mixed systems.

Flea beetles landing on cover crop plants spent considerable time entangled in Vicia sativa branches or attempting to reach the upper part of the tall Vicia faba plants from which they could fly away. It is possible that the beetles characteristic movement on these two species of cover crops increased their risk of predation and the time and energy expended before they reached suitable host plants. Nevertheless, it seems that the detected flea beetle emigration rates were more than sufficient to account for the population trends observed.
Analysis of covariance: an alternative to nutritional indices
Authors: Raubenheimer D. , Simpson S. L.
Published: April 2011

Some statistical problems are added to the growing list of cautionary tales regarding the use of the conventional, ratio‐based nutritional indices (RCR, RGR, ECI, AD and ECD). Analysis of ratios is based on the, probably unrealistic, assumption of an isometric relationship between denominator and numerator variables. Analysis of covariance (ANCOVA) makes less restrictive assumptions, and additionally provides important information about the data which is lost by using ratio variables. We demonstrate, using computer‐generated data sets, some of the pitfalls of statistical analysis of ratios and illustrate how these may be avoided using ANCOVA. Some possible consequences of such statistical iniquities for biological interpretations are discussed.
Diapause induction in the codling moth, Cydia pomonella: effect of larval diet
Authors: Steinberg S. , Podoler H. , Applebaum S. W.
Published: April 2011

The effect of larval diet on diapause induction in the Israeli strain of the codling moth, Cydia pomonella (L.), was studied in a field trial using intact apple fruits of two varieties: ‘Ana’ (early‐ripening, in the end of June) and ‘Granny Smith’ (late‐ripening, in October). Diapause incidence increased as fruit age (determined as days from fruit‐set) progressed. These results corroborate former studies on other strains of the codling moth, where excised fruits were used.

The combination of 80‐day‐old, fully ripe, ‘Ana’ fruit treatment with the longest days of the year, yielded 38% diapause. This result demonstrates that mature fruit (inducing diapause) cannot completely override the effect of long day (averting diapause), but does confirm that larval diet modifies the photoperiodic induction of diapause in the codling moth.
Stylet activities and potato virus Y vector efficiencies by the aphids Brachycaudus helichrysi and Drepanosiphum platanoidis
Authors: Powell G. , Harrington R. , Spiller N. J.
Published: April 2011

Stylet penetration activities of two aphid species were recorded electrically and compared with their efficiency of potato virus Y transmission. B. helichrysi (Kltb.) acquired the virus during 15% of single penetrations on infected leaves. These acquisitions were associated with the occurrence of cell membrane puncture by stylets, recorded during 44% of the penetrations. D. platanoidis (Schrank) punctured membranes during only 8% of penetrations, and its acquisition efficiency was less than 1%. The frequency with which aphids puncture cell membranes appears to partially determine their vector efficiency.
Onion fly egg distribution in soil: a new sampling method and the effect of two granular insecticides
Authors: Havukkala I. , Harris M. O. , Miller J. R.
Published: April 2011

A method for rapidly determining the vertical and horizontal distribution of insect eggs in fragile soil is described. Liquefied agar is allowed to permeate intact soil samples from below; after cooling, the resulting solid is cut into thin sections, from which eggs can be recovered by washes with hot water. This technique revealed that in organic (muck) soil in the laboratory, undisturbed onion flies, Delia antiqua (Meigen) (Diptera: Anthomyiidae), laid 95% of their eggs within a 10 mm diameter zone around the base of a surrogate onion ‘stem’ arising vertically from the soil. Ninety % of all eggs were found in the top 12 mm of soil, with an apparent maximum at depth of 2–4 mm. Increasing fly density from 30 to 200 flies per 30 × 30 × 42 cm cage flattened the horizontal distribution of eggs and extended the ovipositional range from c. 15 mm to beyond 60 mm, suggesting there was competition for the preferred ovipositional sites. Surface treatment of muck soil in the field by granular formulations of the insecticides Lorsban™15 G (active ingredient chlorpyrifos) and Dyfonate™15 G (fonofos) three weeks prior to bioassaying reduced egg‐laying at depths greater than 8 mm. The relation between the measured egg distribution and mortality factors in soil (low moisture and high temperature) is discussed.
Host plant recognition in monophagous weevils: Specialization of Ceutorhynchus inaffectatus to glucosinolates from its host plant Hesperis matronalis
Authors: Larsen L. M. , Nielsen J. K. , Sørensen H.
Published: April 2011

Ceutorhynchus inaffectatus Gyllenhal (Coleoptera: Curculionidae: Ceutorhynchinae) is a monophagous species feeding only on Hesperis matronalis L. (Cruciferae) in North‐western Europe. Feeding responses of this weevil to five glucosinolates from its host plant were compared with the responses to four glucosinolates from non‐host plants. The major glucosinolates in the host plant were isolated and identified: 6‐methylsulphinylhexylglucosinolate (glucohesperalin), 3, 4‐dihydroxybenzylglucosinolate (glucomatronalin), 3‐O‐apiosylglucomatronalin, a 3, 4‐dihydroxybenzoylester and a 3, 4‐dimethoxybenzoylester of 3‐O‐apiosylglucomatronalin. The three glucosinolates containing apiose were powerful feeding stimulants for C. inaffectatus while the other host plant compounds and allylglucosinolate (sinigrin), 3‐methylsulphinylpropylglucosinolate (glucoiberin), benzylglucosinolate (glucotropaeolin) and p‐hydroxybenzylglucosinolate (sinalbin) were weaker stimulants. The role of glucosinolates in host plant selection of C. inaffectatus and related monophagous crucifer feeders is discussed.
Suppression of Ostrinia nubilalis by Trichogramma nubilale in sweet corn
Authors: Prokrym D. R. , Andow D. A. , Ciborowski J. A. , Sreenivasam D. D.
Published: April 2011

We conducted inundative release experiments with Trichogramma nubilale (Hymenoptera: Trichogrammatidae) to suppress Ostrinia nubilalis (Lepidoptera: Pyralidae) in sweet corn (Zea mays): two experiment during O. nubilalis first generation and three experiments during second generation. Five measurements of ear and stalk damage were used to assess O. nubilalis control in treated and untreated plots within each experimental field. In one experiment during second generation, natural O. nubilalis populations were sufficiently high to demonstrate that the parasitoids (three releases totaling 4.4 million parasitoids per ha) parasitized an estimated 57.4% of the placed O. nubilalis egg masses and reduced the mean number of O. nubilalis larvae per ear by 97.4%, the number of tunnels per stalk by 92.9%, and the number of larvae per stalk by 94.3% in the release plot. Ear damage in this experiment was suppressed to meet acceptable standards for use in cut‐corn commercial processing. Larval mortality was apparently density independent, which implies that density‐dependent larval loss would not compensate for egg parasitism by T. nubilale.
Compensatory response of a legume root‐nodule system to nodule herbivory by Sitona hispidulus
Authors: Quinn M. A. , Hall M. H.
Published: April 2011

A laboratory study was conducted to examine the hypothesis that herbivory of nitrogen‐fixing root nodules on legumes causes an exact compensatory response in nodule growth. Plants of Medicago sativa (L.) were grown hydroponically in clear plastic growth pouches so that the number and biomass of root nodules could be estimated nondestructively before, and 10 and 18 days after, partial denodulation. For treatments, plants were subjected to 23% denodulation by first‐instar larvae of Sitona hispidulus (F.) (a common herbivore of Medicago and Trifolium) or 50% nodule pruning; additional plants were left untreated. Results indicated that nodule herbivory and nodule pruning caused an overcompensatory response in number of nodules. This was also true for number of nodule units (an indirect measure of nodule biomass) per plant at 10 days after denodulation but had changed to an exact compensatory response by day 18. An inverse relationship between change in number of nodule units and initial number of nodules indicated that compensatory nodulation was regulated by a feedback mechanism. Shoot and root biomasses were not affected by denodulation in this study.
Response of predatory mites with different rearing histories to volatiles of uninfested plants
Authors: Takabayashi J. , Dicke M.
Published: April 2011

The behavioural response of the predatory mite Phytoseiulus persimilis to volatiles from several host plants of its prey, spider mites in the genus Tetranychus, was investigated in a Y‐tube olfactometer. A positive response to volatiles from tomato leaves and Lima bean leaves was recorded, whereas no response was observed to volatiles from cucumber leaves, or leaves of Solanum luteum and Solanum dulcamara.

Different results were obtained for predators that differed in rearing history. Predators that were reared on spider mites (Tetranychus urticae) on Lima bean leaves did respond to volatiles from Lima bean leaves, while predators that had been reared on the same spider mite species but with cucumber as host plant did not respond to Lima bean leaf volatiles. This effect is compared with the effect of rearing history on the response of P. persimilis to volatile allelochemicals of prey‐infested plant leaves.