bluuebunny/crossref_metadata_2025 huggingface dataset:
La répartition spatiale des différents stades de Coccinella septempunctata dans un champ de blé: variation au cours de la saison
Authors: Ferran A. , Gubanti P. , Iperti G. , Migeon A. , Onillon J.
Published: April 2011

Au début du printemps les adultes de Coccinella septempunctata L. (Col., Coccinellidae) issus des sites d'hivernation, les larves et les nymphes qui en proviennent, fréquentent le sol et les parties basses du blé. En juin, les adultes nés dans le champ et leur descendance sont dispersés sur toute la hauteur des talles bien qu'une fraction non négligeable de leur population se rencontre à l'extrémité supérieure. La plupart des pontes sont déposées sous les mottes de terre, les pierres et les petites adventices qui constituent des sites privilégiés. Ces variations de la distribution de cette coccinelle peuvent être mises en relation avec le climat, en particulier la température, avec la thermophilic de cette espèce et avec la répartition sur les différentes parties des talles des 3 espèces de puceron qui se succèdent au cours de la saison. Ces observations sont importantes à considérer lors du choix ou de la mise au point d'une méthode d'échantillonnage.

Vertical distribution of Coccinella septempunctata in wheat field: change during plant growth time

At the beginning of spring, post‐hibernating adults of Coccinella septempunctata L. (Col., Coccinellidae), larvae and nymphs are found on the lower part of wheat plants. In June, adults born in the field as well as their progeny are dispersed all over the plant and a significant proportion of them is found on the apical parts of plants. Most of the egg clutches are layed on soil lumps, stones and small wild plants which represent preferential sites. Variations in coccinellid distribution may be influenced by climatic conditions, especially the temperature, by the thermophilic nature of this species and by the repartition of the three main aphid species on the plants. These results are relevant for the selection of a sampling methods.
Selection for rate of development and pupal weight in ‘Cnephasia’ jactatana: A genetic tool for quality improvement
Authors: Ochieng‘‐Odero J. P. R.
Published: April 2011

Selection for fast and slow rate of pupation over three successive generations in ‘Cnephasia’ jactatana (Walker) (Lepidoptera: Tortricidae) produced a ‘fast strain’ that pupated 2 days earlier than the ‘slow strain’. Selection for pupal weight was asymmetrical with the ‘light’ selection having more effect than the ‘heavy’ selection. The larval critical weight (LCW), the larval maximum weight (LMW) and the latent feeding period were not affected by any of the selections. ‘Slow’ and ‘light’ selections resulted in longer pre‐pupal periods than ‘fast’, ‘heavy’ or the laboratory population. Fecundity was reduced in females from ‘slow’ and ‘light’ selections. Selection in insects is discussed as a possible genetic tool for overall quality improvement.

La sélection de la vitesse de développement et du poids des chrysalides de ‘Cnephasia jactatana’: outil génétique pour l'amélioration des caractéristiques

La sélection pour la rapidité d'apparition des chrysalides de C. jactatana Walker produit en 3 générations une lignée ‘rapide’ qui se nymphose 2 jours avant la ‘lente’. La sélection pour le poids des chrysalides est asymétrique, ayant plus d'effet sur la sélection développement lent que sur la sélection développement rapide. Le poids critique larvaire (LCW), le poids larvaire maximal (LMW) et la période latente d'alimentation ne sont pas modifiés par ces sélections. Les lignées ‘lente’ et ‘légère’ ont des périodes prénymphales plus longues que les lignées ‘rapide’ et ‘lourde’, ou la souche de laboratoire. Les fécondités des lignées ‘lente’ et ‘légère’ sont réduites. Les sélections associées des insectes sont examinées comme outil génétique potentiel permettant d'améliorer les performances globales.
Critical, pupal and adult weights in the size related metamorphosis of the black lyre leafroller ‘Cnephasia’ jactatana
Authors: Ochieng‘‐Odcro J.P.R.
Published: April 2011

Adult reproductive performance is linked to the period of feeding done by the final instar larva after attainment of a larval critical weight (LCW). The highest weight attained by a final instar larva is referred to as the larval maximum weight (LMW) and is the onset of the pre‐pupal period. The relationships between LCW, pupal weight (PW) and adult weight (AW) are described as functions of the LMW. In the leafroller ‘Cnephasia’ jactatana (Walker) (Lepidoptera: Tortricidae), LCW was dependent on larval size and was approximately 75% of the mean LMW. LCW was about 29 mg and 36 mg for male and female larvae of 1.18 mm and 1.20 mm head‐capsule width, respectively. Over three successive generations of laboratory rearing, PW was approximately 30% and 25% lower than the LMW for males and females, respectively. AW was consistently about 50% and 40% lower than the PW for males and females, respectively. The decrease in weight from LMW to PW was named as the constant DP and found to be 0.3 for males and 0.25 for females. The total decrease from LMW to AW was the constant DA and was 0.6 for males and 0.5 for females. The duration of the latent feeding period was positively correlated to PW and AW. LCW may be used to derive quality indices that describe and predict pupal and adult performance.

Poids critiques des chrysalides et des adultes liés à la métamorphose de ‘Cnephasia’ jactatana

Les performances reproductives sont liées à la période d'alimentation du dernier stade larvaire après l'obtention d'un poids critique (LCW). Le poids maximal atteint au dernier stade larvaire est défini comme le poids larvaire maximal (LMW), il correspond au début de la période prénymphale. Les relations entre poids de la chrysalide (PW) et poids de l'adulte AW) sont présentées comme des fonctions de LMW). Chez ‘Cnephasia’ jactatana Walker (Lep. Tortricidae), Lcw dépend de la taille de la chenille et correspond à environ 75% de la valeur moyenne de LMW. LCW est respectivement de 29 mg et 36 mg pour les chenilles mâles et femelles dont les capsules céphaliques ont 1,18 et 1,20 mm. Pour 3 générations successives, PW est environ 30% et 25% inférieur à LMW des mâles et des femelles. La régression du poids de LMW à PW est désignée comme la constante DP et vaut 0,3 pour les mâles et 0,25 pour les femelles. La régression de LMW à AW est désignée comme la régression DM et vaut 0,6 pour les mâles et 0,5 pour les femelles. La durée de la période d'alimentation latente est liée positivement à PW et AW, LCW peut être utilisé comme indice dérivé décrivant et prédisant les potentialités nymphales et imaginales.
The significance of shelter for young cutworms (Agrotis segetum)
Authors: Esbjerg P.
Published: April 2011

The importance of shelter for young Agrotis segetum Schiff. (Lep. Noctuidae) larvae was investigated using caged carrots (Daucus carota L.) with the soil surface covered only by paraffin wax, or with a layer of vermiculite resembling dry soil on top of a layer of paraffin wax. In the vermiculite treatment, most cutworms were found in the vermiculite with only a small proportion on the plant foliage, whereas in the paraffin wax treatment, the majority was found on the foliage. Larval growth rate was higher and mortality lower among the cutworms which could shelter in the vermiculite than amongst those with no shelter. These results agree with those from previous investigations which showed that moist soil prevented the larvae from sheltering in it. The importance of shelter in dry soil cannot be fully explained, but it may provide a more favourable temperature for larval development.

Importance des abris pour les jeunes chenilles d'Agrotis segetum

L'importance des abris pour les jeunes chenilles d'A. segetum a été examinée en utilisant des carottes (Daucus carota) dans des cages dont le sol était recouvert d'une couche de paraffine ou d'une couche de vermiculite mimant du sol sec au‐dessus de La couche de paraffine. La plupart des vers gris ont été trouvés dans la couche de vermiculite contre une faible proportion dans le feuillage, tandis qu'en absence de vermiculite la majorité a été retrouvée dans le feuillage. La croissance larvaire était meilleure et la mortalité plus faible avec la vermiculite. Ces résultats sont conformes à des observations antérieures qui avaient montré qu'un sol humide empechait les chenilles de s'y abriter. L'importance de l'abri en sol sec n'est pas entièrement expliquée, mais celui‐ci pourrait assurer une température plus favorable au développement larvaire.
Colonization pattern in the pine shoot beetle, Tomicus piniperda: Effects of host declination, structure and presence of conspecifics
Authors: Schlyter Fredrik , Löfqvist Jan
Published: April 2011

A survey of 100 Scots pine trees (Pinus sylvestris) showed that those windthrown with a declination > 50° from vertical were preferentially colonized by the larger pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae). A factorial experiment was done with logs of 0°, 45° and 90° declination, and different diameters and spacing to test hypotheses, involving olfactory, visual and tactile mechanisms. In the experiment, the attack rates depended strongly on log diameter with a preference being shown for larger diameter logs having a rough bark structure. In contrast to the field survey, experimental declination did not increase attack densities. The spacing between neighbouring attack sites in the bark was regular rather than random, which could be due both to spacing between conspecifics and regularities in bark structure. The contrary data from survey and experiment is explained by release of odours from wind damaged trees, and host odour and bark roughness stimuli are suggested to operate in different steps in the behavioural sequence of host location and colonization.

Conditions de la colonisation des pins par Tomicus piniperda: effets de l'inclinaison, de la structure de l'hôte et de la présence de congénères

L'observation de 100 individus de Pinus sylvestris a montré que les arbres inclinés de plus de 50° par le vent sont colonisés de préférence par T. piniperda L., Scolytidae. Des expériences avec des branches de différents diamètres, plus ou moins espacées et inclinées de 0°, 45° et 90°, ont permis d'examiner les influences de l'olfaction, de la vision et du tact. Les attaques ont montré une préférence marquée pour les diamètres les plus grands et pour la structure la plus rugueuse. Contrairement aux observations dans la nature, l'inclinaison n'a pas augmenté les attaques.

L'analyse sur l'écorce de la distance entre les points d'attaque montre une tendance à une distribution régulière plutôt qu'au hasard, tenant compte de la régularité structurale de l'écorce.

Les résultats contradictoires entre les expériences et les observations peuvent s'expliquer par l'abondante émission d'odeurs par les arbres endommagés par le vent, paramètre non contrôlé dans les observations. Les stimuli dus à la rugosité et à l'odeur de l'arbre devraient opérer à différentes étapes de la découverte et de la colonisation de l'hôte.
Importance of color stimuli in host‐finding by Dalbulus leafhoppers
Authors: Todd J. L. , Harris M. O. , Nault L. R.
Published: April 2011

The importance of color stimuli in host‐finding by Dalbulus maidis (DeLong & Wolcott), D. gelbus DeLong, and D. quinquenotatus DeLong & Nault (Homoptera: Cicadellidae) was determined by comparing pre‐ and post‐contact responses of leafhoppers to maize seedlings (Zea mays L.) with those to vertical models varying in hue or value (total amount of reflected light). For each species, more contacts were made with maize by jumping/flying than by walking, and both sexes remained on maize for similar times after contact. When presented simultaneously with seven models (vertical wooden rods) painted in different colors, each species made more contacts with yellow. Yellow also received more contacts when it was present in a group of four colors. There were no differences in contacts made with the yellow model by jumping/flying or by walking for D. maidis and D. gelbus, but D. quinquenotatus made more contacts by jumping/flying than by walking. If yellow was not present in the group, the color reflecting maximally between 500–580 nm received more contacts compared to the other three colors. Responses to a series of neutrals indicated contacts were elicited primarily because of hue, and not changes in value. Yellow also elicited tenure as long or significantly longer than other colors after contact with a model. For each species, there were no differences in tenure between males and females on models. The importance of color stimuli in host‐finding by Dalbulus leafhoppers is suggested to be influenced by differences in flight behavior and habitat stability of field hosts.

Importance de la couleur dans la découverte de l'hôte par Dalbulus

Nous avons examiné l'importance de la couleur dans la découverte de l'hôte, en comparant au laboratoire les réactions avant et après contacts avec des plants de maïs, – à 4 feuilles –, et avec des leurres peints présentant des différences de nuance ou de quantité de lumière réfléchie, chez 3 espèces de Dalbulus: D. maidis, – spécialiste du maïs –, D. gelbus, – qui consomme le maïs et Tripsacum, et D. quinquenotatus, – spécialiste de Tripsacum. Les espèces entrent en contact avec le maïs plus en voltigeant que par la marche, mâles et femelles séjournant plusieurs heures après être entrés en contact. En utilisant des leurres végétaux, – des morceaux de bois verticaux peints de différentes couleurs –, une forte réponse au jaune, due à la teinte plus qu'à l'intensité, a été mise en évidence. Il n'y a pas de différence dans les contacts après voltige ou après marche avec des leurres jaunes pour D. maidis et D. gelbus, tandis que chez D. quinquenotatus, ils sont plus fréquents après voltige. Ces 3 espèces de Dalbulus continuent à être influencées par la couleur après contact, puisque chaque espèce reste plus longtemps sur le jaune que sur les autres couleurs. L'importance de la stimulation par la couleur dans la découverte des hôtes par Dalbulus est semble‐t‐il due au comportement de vol et à la stabilité de l'habitat dans la nature.
Embryonic growth rate and birth weight of the offspring of apterous and alate aphids: a cost of dispersal
Authors: Newton C. , Dixon A.F.G.
Published: April 2011

Apterous and alate Sitobion avenae (Fab.) were dissected from the third instar onwards and the size and degree of development of their largest embryos recorded. From at least the third instar apterae had larger and more well developed embryos than alatae. Embryos in both morphs showed an exponential increase in volume with time during their mothers' nymphal development, but those in apterous mothers grew faster. Although alatae had a longer pre‐reproductive development than apterae, it was not long enough to compensate for the lower embryo growth rates in alatae and as a consequence they initially produced smaller and fewer offspring than apterae. After 4 days of reproduction apterous and alate mothers produced similar sized offspring and at the same rate. The total fecundity of apterae was greater than that of alatae.

Taux de développement embryonnaire et poids à la naissance des pucerons aptères ou ailés: coût de la dispersion

La taille et l'état de développement des plus gros embryons de Sitobion avenae Fab ont été examinés par dissection d'ailés et aptères à partir du troisième stade. La taille des embryons des 2 morphes augmente pendant le développement larvaire des mères, mais ceux des mères aptères grossissent plus vite. Bien que la période précédant la reproduction des alates soit plus longue chez les ailés que chez les aptères, les embryons des ailés sont néanmoins incapables de l'emporter en taille sur les aptères, et les ailés produisent initialement moins de pucerons et plus petits que les aptères. Après 4 jours de reproduction, les mères ailées et aptères produisent des pucerons de même taille au même rythme. La fécondité totale des aptères est supérieure à celle des ailés; la différence est liée à la biologie des 2 morphes.
Calling behaviour of Mamestra brassicae: effect of age and photoperiod
Authors: Noldus L. P. J. J. , Potting R. P. J.
Published: April 2011

Die periodicity of calling and the effect of age and photoperiod on calling behaviour were studied in virgin females of the cabbage moth, mamestra brassicae L. (Lepidoptera: Noctuidae). No calling activity was observed during the first scotophase. Most females called for the first time during the 2nd or 3rd scotophase after emergence, regardless of the photoperiod. Moths maintained under 16L: 8D started calling significantly later in the scotophase than those maintained under 18L: 6D. With increasing age, moths initiated calling significantly earlier. Under the 16L: 8D photoregime, the mean onset calling time decreased from scotophases 2 to 3, after which it stabilized around ca. 260 min after the start of the scotophase. With 18L : 6D, the onset of calling decreased until scotophase 4, and subsequently stabilized around ca. 130 min after lights off.

Effet de l'âge et de la photopériode sur le comportement d'appel de Mamestra brassicae

La périodicité quotidienne de l'appel et les effets de l'âge et de la photopériode ont été examinés sur des femelles vierges de Mamestra brassicae (Lépido., Noctuidae). Aucun appel n'a été observé pendant la première scotophase; la plupart des femelles appelaient pour la première fois pendant les 2e et 3e scotophases après l'émergence, quelle que fût la photopériode. Les papillons conservés à 16 J/8 N ont commence à appeler beaucoup plus tard que ceux dont la photopériode était 18 J/6 N. En vieillissant, les papillons appelaient significativement de plus en plus tôt. Avec 16 J/8 N, la moyenne du moment du début de l'appel a diminué de la scotophase 2 à la scotophase 3, après laqueile il s'est stabilisé autour de 260 min après le début de la scotophase. Avec 18 J/6 N, le moment du début de l'appel a diminué jusqu'à la scotophase 4, et s'est stabilisé ensuite autour de 130 min après le début de l'obscurité.
Behavioural variation among strains of Trichogramma spp.: host‐species selection
Authors: Pak G. A. , Kaskens J. W. M. , de Jong E. J.
Published: April 2011

The host‐selection behaviour of nine strains of Trichogramma spp., towards eggs of Mamestra brassicae, Pieris brassicae and P. rapae, was investigated in laboratory experiments in order to select candidate strains for inundative releases against these species. Experiments were carried out by continuously observing the behaviour of individual females, which were offered equal numbers of eggs of two host species arranged in a grid. M. brassicae was a highly acceptable host species for all strains, whereas the acceptability of the two Pieris species was similar within strains, but varied between strains. Considering the variation in acceptance of Pieris eggs, strains either showed: (1) no preference between Mamestra and Pieris (High Pieris Acceptance = HPA strains), (2) a preference for Mamestra (Variable Pieris Acceptance = VPA strains), or (3) an aversion for Pieris Le comportement de sélection de l'hôte par neuf souches de Trichogrammes, vis‐à‐vis d'œufs de Mamestra brassicae, Pieris brassicae et P. rapae a été étudié au laboratoire afin de sélectioner des souches candidates pour des lâchers inondatifs contre ses espèces. Des expériences ont été menées par observations en continu du comportement de femelles auxquelles était offert un nombre égal d'œufs de deux espèces d'hôtes, disposés selon un grille. M. brassicae est un espèce‐hôte fortement acceptée par toutes les souches. Au contraire, l'acceptabilité des deux espèces de Pieris, semblable pour chaque souche, varie entre les souches. En tenant compte de la variation d'acceptance des œufs de Pieris les souches (1) ne montrent aucune préférence entre Mamestra et Pieris, (2) montrent une préférence pour Mamestra, ou (3) une aversion pour Pieris. Des femelles des souches du second groupe acceptent fortement les œufs de Pieris si les œufs de Mamestra, préférés, sont absents. Comparativement, elles rentrent en contact avec moins d'œufs de Pieris en présence d'œufs de Mamestra. Ceci indique une sélection des hôtes à distance. Les souches du premier groupe sont probablement les meilleures candidates pour des lâchers inondatifs.
Ambulatory dispersal and life history response to food deprivation in twospotted spider mites
Authors: Krainacker David A. , Carey James R.
Published: April 2011

A major life history characteristic of the twospotted spider mite, Tetranychus urticae Koch, is the ability to disperse between different hosts. This may be done by aerial or ambulatory means. Although there have been a number of studies dealing with mite dispersal, most have been qualitative in nature and examine only the overall process. In this study we measure the ambulatory dispersal capabilities of twospotted spider mite adult females and males, as well as that of deutonymphs, protonymphs and larvae at distances up to 480 cm. Additionally, for adult females only vertical (upwards and downwards) distances of up to 240 cm were measured. We also measured the influence of food deprivation on spider mite longevity and fecundity by depriving mites of food for one, two or three days immediately after ecdysis at 24 or 30 °C, or food deprivation for one, two or three days (at 24 °C) after feeding as adults for five days. Dispersal efficiency, defined as the percentage of individuals successfully crossing the test distance, generally increased with time and decreased with distance. As expected, dispersal efficiency was shown to be related to stage, with adults the most efficient and larvae the least. Food deprivation studies revealed that at 24 °C mites were capable of withstanding two days without food before longevity and fecundity began to decrease.

L'aptitude à la dispersion de Tetranychus urticae

Tetranychus urticae Koch est caractérisé par son aptitude à la dispersion sur différents hôtes. Nous examinons 2 aspects de celle‐ci: 1) aptitude à la dispersion à faible distance en rampant; 2) effet de la perte de contact avec l'hôte (par suite de la dispersion) sur la survie et la fécondité. En ce qui concerne la dispersion à faible distance, la mesure a porté sur l'aptitude de chaque stade à parcourir différentes distances jusqu'à 480 cm. De plus, pour les femelles la mesure a concerné seulement la dispersion verticale jusqu'à 240 cm. L'efficacité de la dispersion était plus élevée sur les faibles distances; l'aptitude à la dispersion était liée au stade, les adultes étant meilleurs que les larves. Les effets de la privation de nourriture ont été en particulier:

a) que les acariens sont capables de survivre 2 jours à 24 °C sans aliments avant que longévité et fécondité ne diminuent;

b que des acariens privés d'aliments pendant 3 jours à 24 ou 30 °C ont présenté une mortalité très élevée. Aucun acarien ne survécut à 3 jours de jeûne à 30 °C;

c) La température pendant le jeûne a déterminé le temps pendant lequel les acariens ont pu supporter le jeûne.
In vivo effect of mixtures of allelochemicals on the life cycle of the European corn borer, Ostrinia nubilalis
Authors: Bernard C.‐B. , Arnason J. T. , Philogène B. J. R. , Lam J. , Waddell T.
Published: April 2011

The phenylpropanoid, dillapiol, a compound capable of inhibiting the activity of cytochrome P‐450 epoxidase in microsomal preparations of midguts of the European corn borer (ECB), Ostrinia nubilalis Hubner (Lepidoptera), did not enhance the toxicity of two insecticidal allelochemicals from the Asteraceae: the sesquiterpene lactone, tenulin or the phenylacetylene, phenylheptatriyne, when ingested simultaneously. Dillapiol alone was toxic to ECB larvae, and inhibited their growth. Possible reasons for the lack of synergism or potentiation by dillapiol of the insecticidal activity of the other allelochemicals are considered.

Effets in vitro des mixtures de substances allélochimiques sur le cycle biologique de la pyrale du maïs, Ostrinia nubilalis

Le dillapiolc, un phénylpropanoide monomère d'un lignait et contenant un groupement méthylènedioxyhphényl (MDP), a la capacité d'inhiber in vitro les enzymes d'oxydations multiples à cytochrome P‐450 (PSMO) utilisées par la pyrale du maïs (ECB), Ostrinia nubilalis, pour dctoxifier les substances allélochimiques. Les composés contenant un groupe MDP comptent parmi les plus nombreux et puissants synergistes d'insecticides. Cependant, aucun synergisme n'est observé lorsque le dillapiole est ingéré par la pyrale en association avec l'une ou l'autre ou les deux substances secondaires insecticides des Astéraceae, la lactone sesquiterpène ténuline ou/et le polyacétylène phénylheptatriyne (PHT). Plutôt, le dillapiole est une toxine qui diminue la prise de poids des larves et retarde leur développement. Les effets toxiques sont plus importants avec le dillapiole seul que lorsque celui‐ci est associé à la ténuline ou/et au PHT. Les expications possibles de ces résultats sont discutées.
Pathogenic fungal dynamics in a fall population of the blackmargined aphid (Monellia caryella)
Authors: Ekbom Barbara Sohm , Pickering John
Published: April 2011

A fall population of the blackmargined aphid, Monellia caryella (Fitch) (Homoptera; Aphididae), was monitored daily for mortality caused by fungi and parasitoids. Three species of Entomophthorales fungi were found. Fungal‐induced mortality was found to be correlated with minimum temperature. During the period when the minimum temperature was consistently above 8 °C, fungal‐induced mortality was positively correlated with the sum of hours of leaf‐wetness on days 5, 6, and 7 before sampling. Parasitoid wasps killed fewer hosts than fungi and were not affected by environmental factors.

Dynamique des champignons pathogènes d'une population automnale du puceron Monellia caryella

La mortalité quotidienne provoquée par des parasitoïdes et des champignons sur une population automnale de M. caryella Fitch (Homopt. Aphididae) a été suivie à Byron (Géorgie, USA), avec enregistrement de la température, de la pluie et de l'humidité des feuilles. 3 espèces de champignons entomophthorales ont été trouvées: Neozygites sp., Entomophthora planchoniana et Erynia sp. 54% des pucerons morts étaient contaminés par Neozygites et 46% par E. planchoniana. Seuls 2 pucerons avaient été tués par Erynia sp. Les taux de mortalité quotidienne par champignons s'élevaient après les périodes pluvieuses et d'humidité des feuilles. La mortalité due au parasitisme était inférieure à la mortalité due aux champignons et ne semblait pas liée aux conditions écologiques. La discussion porte sur l'importance de la mortalité provoquée par les champignons sur la dynamique de la population de pucerons.
Evolutionary genetics of the aphid Cryptomyzus, with a preliminary analysis of the inheritance of host plant preference, reproductive performance and host‐alteration
Authors: Guldemond J. Adriaan
Published: April 2011

The aphid species Cryptomyzus galeopsidis (Kaltenbach) includes several distinct forms which have different host plant relationships and life cycles. Cross breeding was used to elucidate the taxonomic status of these forms and to investigate the inheritance of host preference, reproductive performance and host‐alternation. One of the forms appeared to be a distinct species because of the reduced fitness of the hybrids. Other host‐alternating and non host‐alternating forms are considered conspecific and represent two life cycle strategies. Reproductive performance is probably controlled polygenically, since hybrids show an intermediate performance. Host preference in hybrids showed some degree of dominance and seemed to be determined by only a few genes. Host‐alternation is presumed to be inherited monofactorially. The implications for speciation are discussed.

Etude de l'hybridation chez les pucerons du genre Cryptomyzus, et observations sur la génétique du choix des hôtes, de leur alternance et des performances reproductives

C. galeopsidis Kaltenbach contient plusieurs formes qui ont différentes relations avec des plantes hôtes et des cycles distincts. Des croisements ont permis d'élucider la taxonomie de ces formes et d'étudier l'hérédité de préférences d'hôtes, des performances reproductives et de l'alternance d'hôtes. Une des formes apparaît comme une espèce distincte par suite de la valeur adaptative réduite des hybrides. Les autres formes avec alternance ou non des hôtes sont considérées comme conspécifiques et représentant deux stratégies vitales différentes. Les performances reproductives sont probablement polygéniques puisque les hybrides ont des performances intermédiaires. Les préférences d'hôtes des hybrides montrent certains degrés de dominance et semblent déterminées par quelques gènes seulement. L'alternance des hôtes est envisagée comme ayant une hérédité monofactorielle. Les conséquences sur la spéciation sont discutées.
Ascending flights for migration of the oriental armyworm, Pseudaletia separata
Authors: Hirai Kazuo
Published: April 2011

Flight behavior of Pseudaletia (= Mythimna) separata Walker (Lepidoptera: Noctuidae) was observed around sunset in a grassland habitat at Morioka in northern Japan. Take‐off flights by both females and males commenced on the first day following emergence. The proportion of moths flying increased gradually with age from 62% on day 1 to 86% on day 5. Flight could be categorized as ‘ascending’ or ‘short range’, 2 to less than 10 m flights in the observation. The proportion of adults making ascending flights increased from 47% on day 1 to a maximum of 55% on day 2, and then gradually decreased to 29% on day 5. It is considered that the ascending flight is connected with long‐distance migration. Mated femáles with matured eggs did not make ascending flights, but mated males did. Adults embarked on those flights at temperatures of 7.5 °C or greater. On rainy days fewer adults flew upwards than on non‐rainy days. The related species, Leucania pallens, did not fly up, but flew at slow speed at low altitude.

Vols ascendants initiateurs de migrations de Pseudaletia separata

Le comportement de vol de Pseudaletia (Mythimna) separata Walker (Lep., Noct.) a été observé vers le crépuscule au dessus de prairies à Morioka (Japon septentrional). Les envois des femelles et des mâles débutent le jour suivant l'émergence. La proportion de papillons en vol augmente progressivement, de 62% le premier jour, à 86% le 5e jour. Les vols peuvent être classés en ascendants (2 à 10 m) ou à courte distance (inférieurs à 2 m). La proportion d'adultes effectuant des vols ascendants augmente, de 47% le premier jour, à un maximum de 55% le 2e jour, pour diminuer progressivement jusqu'à 29% le 5e jour. On considère que les vols ascendants sont lié aux migrations à longue distance. Les femelles fécondées contenant des œufs mûrs ne font pas de vols ascendants, tandis que les mâles ayant eu une activité sexuelle le font. Les adultes effectuent de tels vols aux températures supérieures ou égales à 7.5 °C. Par temps pluveuxmoins d'adultes ont des vols ascendants que par temps sec. L'espèce voisine, Leucania pallens n'effectue pas de vols ascendants, mais vole à faible vitesse à basse altitude.
Realized heritability estimation for pesticide resistance traits
Authors: Rosenheim J.A.
Published: April 2011

Tanaka & Noppun (1989) have described a procedure for estimating realized heritabilities, h2, from artificial selection experiments for pesticide resistance. Here I describe three processes especially relevant to such selection experiments that may introduce important biases into resulting estimates of h2. First, imperfect bioassays, in which different individuals receive different doses, have diminished abilities to discriminate between individuals on the basis of their tolerances. This results in an overestimate of S, the selection differential, and a corresponding underestimate of h2. Second, sublethal effects of pesticide exposure may generate variation in reproductive output among survivors of a round of artificial selection, with more tolerant individuals frequently producing more progeny. This results in an underestimate of S and a corresponding overestimate of h2. Third, unequal selection applied to males and females, especially likely to occur when mass selection is applied to adults of both sexes after mating has occurred, may cause S to be overestimated and h2 to be underestimated. Biases introduced by these processes may in some cases be large, adding an unacceptable amount of uncertainty to h2 estimates. Only if these biases are avoided can heritability estimates be usefully incorporated into prospective models of resistance evolution.

Estimation réaliste de l'héritabilité de la résistance aux pesticides

Tanaka & Noppun (1989) ont décrit une procédure d'estimation réaliste de l'héritabilité, h2, lors d'expériences de sélection artificielle de résistance aux pesticides. Je décris ici 3 processus liés particulièrement à de telles expériences de sélection pouvant introduire des biais importants dans l'estimation de h2. Premièrement, des tests imparfaits, au cours desquels différents individus reçoivent différentes doses, ont réduit les possibilités de distinguer les individus en fonction de leur tolérance; ceci conduit à la surestimation de S, la sélection différentielle, et à une sous‐estimation parallèle de h2. Deuxièmement, les effets sublétaux de l'exposition aux pesticides peuvent provoquer une variation de l'impact reproducteur des survivants au cours de la sélection artificielle, les individus les plus tolérants produisant souvent plus de descendants; ceci entraine une sous‐estimation de S et une surestimation correspondante de h2. Troisièmement, une sélection inégale des mâles et des femelles, particulièrement quand une sélection de masse affecte les adultes des deux sexes après les accouplements, peut provoquer une surestimation de S et une sous‐estimation de h2. Les biais introduits par ces processus peuvent être dans certains cas importants, ajoutant une part inacceptable d'incertitude dans les estimations de h2. Ce n'est que si biais sont évités que l'estimation de l'héritabilité peut être incorporée utilement dans les modèles prospectifs de l'évolution de la résistance.
Stimuli influencing host microhabitat location in the parasitoid Campoletis sonorensis
Authors: McAuslane H.J. , Vinson S.B. , Williams H.J.
Published: April 2011

The host microhabitat location behavior of females of the generalist parasitoid Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae) was studied in a wind tunnel. Visual cues associated with the host plant cotton, Gossypium hirsutum L., were important and significantly more parasitoids completed flights to a damaged 4‐leaf cotton plant bearing a Heliothis virescens (F.) (Lepidoptera: Noctuidae) larva and frass than to a similarly damaged single leaf with frass and a larva. This difference in completed flights was not due to differences in amounts of volatiles released by the two stimuli, Both naive and experienced parasitoids responded differently to an undamaged cotton leaf, a mechanically damaged leaf, a naturally damaged leaf with the host removed and a naturally damaged leaf with a host larva. Parasitoids completed significantly fewer flights to the undamaged sources of volatiles than to damaged sources of volatiles. Experienced females responded strongly to all types of damage. The number of flights completed by naive females to the three types of damage differed but not significantly and was less than the number completed by experienced females. Components of the preflight experience were varied to determine which factors were responsible for the higher response of experienced females to the host/plant complex. Oviposition was the most important component of this experience. Contact with host frass or plant damage followed by oviposition did not increase the response over that exhibited by females allowed oviposition only. When frass or damaged plant material were contacted without subsequent oviposition, females completed fewer flights than naive females.
Food acceptance by a monophagous and an oligophagous insect in relation to seasonal changes in host plant suitability
Authors: Kooi R. E. , Van de Water T. P. M. , Herrebout W. M.
Published: April 2011

Food acceptance by larvae of two lepidopteran species feeding on Rosaceae, viz. Yponomeuta evonymellus (monophagous) and Y. padellus (oligophagous), was compared. The influence of seasonal changes in plants as food for both insects was examined, in particular, the effects of nitrogen and sorbitol in leaves. In the laboratory, Y. evonymellus accepts Crataegus monogyna, a host plant of Y. padellus, and Y. padellus accepts Prunus padus, the host plant of Y. evonymellus. P. padus is the most suitable food plant for Y. evonymellus. No difference in food‐quality for Y. padellus was found between C. monogyna and P. padus. The performance of both species on P. padus is less influenced by seasonal changes than on Crataegus. The suitability of Crataegus decreases during the season. This is probably caused by the decrease of its nitrogen content, and not by the decrease of sorbitol in the plant. The monophagous, Y. evonymellus, is more sensitive to seasonal changes in its food when fed with a non host plant than the oligophagous Y. padellus. In oviposition experiments both species have a preference for their normal host‐plants.
Feeding site selection of first‐instar larvae of Cnaphalocrocis medinalis on susceptible and resistant rice plants
Authors: Ramachandran R. , Khan Z. R.
Published: April 2011

More first‐instar larvae of the rice leaffolder, Cnaphalocrocis medinalis (Guenée), were recovered from susceptible IR36 and Roxoro rice varieties than resistant TKM6 and Oryza perennis, 24 h after infestation. Within a rice plant, a higher proportion of larvae was recovered from young whorl leaf, followed by mature leaves and leafsheaths on all the four rice varieties tested. However, differences were observed between susceptible and resistant varieties in the distribution of larvae on these three plant parts. In laboratory choice tests, first‐instar larvae preferred to settle on the young leaves of IR36 and TKM6 when presented with their respective mature leaves. No such preference was observed in tests with Rexoro and O. perennis. Larval survival was similar on young and mature leaves of Rexoro. Young leaves of IR36 and TKM6 were more suitable for survival in comparison with their respective mature leaves while the reverse was true for O. perennis. Larval movement was slower on the mature leaves and larvae took longer to reach the whorl leaf of TKM6 than on IR36. The density of trichomes of the abaxial surface of TKM6 was higher than that of the other varieties tested. Adaptive significance of feeding in the leafwhorl to young larvae is discussed.
Glyphosate‐induced changes in the attack success and development of the mountain pine beetle and impact of its natural enemies
Authors: Bergvinson D. J. , Borden J. H.
Published: April 2011

Roundup (active ingredient glyphosate) administered into the sapwood around the root collar of lodge‐pole pine trees, Pinus contorta var. latifolia Engelm., was investigated as a tool for creating trap trees for the mountain pine beetle (MPB), Dendroctonus ponderosae Hopk. MPB's attacked semiochemical‐baited, glyphosate‐treat trees before attacking baited control trees. Bark samples disclosed an increase in survival of MPB eggs and early instar larvae, enhanced larval development and increased attacks by insect parasites and predators in treated trees. The braconid wasp, Coeloides dendroctoni Cush., parasitized MPB larvae found at high densities in treated trees two months following attack. The dipteran predator, Medetera aldrichii Wh., was only found in treated trees. Increased competition by Ips pini (Say) had a negative impact on MPB survivorship. The enhanced impact of insectan agents apparently offset any glyphosate‐induced gains in MPB survival or development, but did not cause a significant reduction in MPB emergence.
Sex pheromones of Spilonota ocellana and Spilonota laricana
Authors: Witzgall P. , Bengtsson M. , Buser H.‐R. , Chambon P.‐J. , Priesner E. , Wildbolz T. , Arn H.
Published: April 2011

The sex pheromones of Spilonota ocellana D. & S. and Spilonota laricana Hein. (Lepidoptera:Tortricidae) were identified by chemical analysis and field trapping. Female moths of the two species produce (Z)‐8‐tetradecenyl acetate, (Z)‐8‐tetradecen‐1‐ol and dodecyl acetate in almost the same proportions (98:1:1 and 97:3:1). Males of both species were best attracted to a blend of 10:1 to 1:1 Z8‐14Ac:Z8‐14OH. This indicates that mating barriers other than sex pheromones exist between sympatric populations.
Factors restricting the feeding of the cabbage stem flea beetle (Psylliodes chrysocephala)
Authors: & E. Bartlet , Williams I. H.
Published: April 2011

The feeding acceptability of 40 different plants to Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) was determined using leaf disc consumption tests for the adult, and stem or petiole penetration tests for the larvae. Only plants that contained glucosinolates were accepted as food, but addition of the glucosinolate sinigrin to rejected food plants did not make them acceptable to adults. Of the 34 plants that contained glucosinolates, nine were either totally or mostly rejected. Solvent extracts of the rejected plants applied to oilseed rape inhibited feeding by adults. The feeding of P. chrysocephala within the group of plants tested is influenced by the presence or absence of glucosinolates, which may act as feeding stimulants, and other, unidentified chemicals which act as feeding inhibitors.
Interference competition in desert subterranean termites
Authors: Jones S. C. , Trosset M. W.
Published: April 2011

We examined interspecific aggression between two subterranean termite species, Heterotermes aureus (Snyder) (Rhinotermitidae) and Gnathamitermes perplexus (Banks) (Termitidae). In laboratory tests with worker termites, neither species was the inherently superior fighter, but rather the outcome of interspecific encounters depended on the number of conspecifics. We then investigated patterns of resource use by these species during a 13‐month period in the Sonoran Desert. Baits consisted of toilet‐paper rolls, which have been shown to be a mutually acceptable food source. Analyses of foraging activity demonstrated that the two species did not forage independently of each other. Not only were the two species negatively associated spatially, but extended periods of temporal segregation were observed. G. perplexus took significantly longer to return to sites that it had simultaneously occupied with H. aureus than to sites that G. perplexus had occupied alone. The pattern of co‐occurrence of these two species is consistent with the hypothesis that interspecific interference competition affects their spatial and temporal distribution.
Resistance and susceptibility of Boronia megastigma cultivars to infestations by the psyllid Ctenarytaina thysanura
Authors: Mensah R. K. , Madden J. L.
Published: April 2011

Studies were conducted on 23 boronia cultivars to determine the mechanisms of resistance and susceptibility to the psyllid, Ctenarytaina thysanura Ferris and Klyver. No antibiosis effects were detected in any of the boronia cultivars investigated. No cultivar was tolerant to C. thysanura attack. However, in both free‐choice and no‐choice tests in the glasshouse, ovipositional antixenosis (non‐preference) was detected in cultivar HC27, whereas cultivars HC4 and HC142 were most preferred for oviposition. Measurement of terminal shoot hardness of cultivars revealed variations in relative hardness. Given a choice between boronia cultivars of the same size and colour but of differing hardness of the terminal shoots, C. thysanura laid more eggs on those cultivars with softer terminal shoots (HC4 and HC142) and laid fewest eggs on harder terminal shoots (HC27). This may explain differences in the psyllid population on different cultivars in the field. Fewer eggs were laid on terminal shoots exceeding a hardness rating of 80 g/mm terminal shoot thickness.
Response to color by male and female Frankliniella occidentalis during swarming and non‐swarming behavior
Authors: Matteson N. A. , Terry L. I.
Published: April 2011

Responses of male and female Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) to colors of various hues and brightness levels were compared between swarming and non‐swarming behavior periods. Relative rankings of color preference were similar between males and females and between swarming and non‐swarming behavior periods. Numbers of thrips were higher on blues, violets, white and somewhat less on some yellows, while lower numbers were found on greens, reds, some yellows and highly UV reflective white. The effect of UV reflection on thrips response to color depended upon the amount of UV reflectance. Highly UV reflective white (78% reflectance at 365 nm) captured very few thrips compared with low UV white (14% reflectance at 365 nm), but colors with less than 35% UV reflectance had no negative effect on numbers of thrips captured compared with their lower UV counterparts. Correlations of average preference rank of colors across all tests with relative rank of brightness of the colors (based on the area under the reflectance curve in different spectral ranges) indicated highly significant correlations of preference with the brightness in the blue‐violet range (R = 0.69 for females; R = 0.86 for males, P < 0.0021), but no significant correlation with brightness in the visible, green‐yellow, or UV range. This contrasts with previous physiological research which indicates that spectral response efficiency of this species peaks in the UV and at 540 nm (green‐yellow range). Several possible physiological, behavioral and color brightness explanations for this discrepancy are discussed.

Significantly higher numbers of male thrips were trapped during swarming (4.5–6.3 ×) compared with non‐swarming behavior periods. Significantly higher numbers of males were trapped than females during swarming behavior periods, but more females were trapped than males during non‐swarming behavior periods. Sex ratios during non‐swarming periods approximated sex ratios found in populations in plants. Based on the density change relative to sex ratio change between behavior periods, there was an indication of a greater change in male behavior than in female behavior. Since males and females responded similarly to color during both behavior periods and attractive colors were similar to flower colors, this suggests that male thrips use resource‐based areas for aggregation sites.
Performance of Piezodorus guildinii on four species of Indigofera legumes
Authors: Panizzi A. R.
Published: April 2011

Piezodorus guildinii (Westwood) (Heteroptera: Pentatomidae), a major pest of soybean in South America, feeds on alternative legume hosts, and four species of Indigofera were tested. Nymphal survival was 88% on I. endecaphylla Jacq. (IE), 15% on I. suffruticosa Mill. (IS), 70% on I. hirsuta L. (IH) and 40% on I. truxilliensis H.B.K. (IT)). From stadia 2 through 5, fastest development (22 days) occurred on IE and IT, and the slowest (29 days) on IS. Fresh body weight at emergence was higher for nymphs fed on IE and IT. Adult survival of P. guildinii after 40 days, was greater than 70% on IT and IE, and less than 20% on IS. Females oviposited on all Indigofera species, but < 30% were observed to lay eggs on IS. Body weight gain during the first week was greater for adults feeding on IE and IH. Insects lost weight on IS; at the end of day 15 no differences in percent change in body weight, among the food plants tested, were observed. Field surveys conducted on IT and IS, the two most abundant species in northern Paraná, indicated a greater number of nymphs, adults, and egg masses on the former host. On both hosts P. guildinii was more abundant during April/May, after soybean harvest, suggesting movement of the populations from soybean to Indigofera.