Jamasb NozariDaniel BurckhardtColin J. JacksonJohn G. Oakeshott...
10页
查看更多>>摘要：Abstract Cacopsylla permixta and Cacopsylla bidens are major pests of pears in Iran. They are commonly sprayed with various insecticides up to 12 times a year but control by these means is no longer reliable, suggesting the evolution of resistance. Here, we report about 60‐fold variation in diazinon susceptibility both among five geographic populations of C. bidens and among three geographic populations of C. permixta, as well as 12‐ to 14‐fold variations in imidacloprid susceptibility in these populations. The levels of resistance to the two compounds were highly correlated in the different populations. Esterase, cytochrome P450, and glutathione S‐transferase activities all varied by about two‐fold among the different populations and were also highly correlated with population resistance to the two insecticides, implying differences in metabolism contribute to the differences in resistance. Bioassays with inhibitors of each class of enzyme indicated all three, but particularly the esterases, contributed to the variation in diazinon resistance, while esterase and, in particular, cytochrome P450 activities contributed to the variation in imidacloprid resistance. The most resistant populations of each species also showed some resistance to chlorpyrifos and acetamiprid, suggesting there may be wide cross resistance to organophosphates and neonicotinoids in these populations. The sampled psyllid populations showed lower levels of resistance to representatives of two other classes of insecticides currently used in Iran, spirotetramat and abamectin, though resistance to spirotetramat was detectable and was correlated with diazinon and imidacloprid resistance across populations. We conclude that metabolic resistance to a range of insecticides is now evolving in field populations of both species in Iran, warranting timely development of resistance management plans.
Thies H. BüscherDennis S. PetersenFabian B?umlerChristian W. W. Pirk...
13页
查看更多>>摘要：Abstract Bee lice (Braulidae) are small parasitic flies, which are adapted to live on their bee host. As such, the wingless Braula coeca is a parasite of the common honey bee Apis mellifera and it is well adapted to attach to its hairy surface. The attachment system of B. coeca provides a secure grip on the fine setae of the bee. This is crucial for the parasite survival, as detachment from the host is fatal for the bee louse. The feet morphology of B. coeca is well adapted to the challenging bee surface, notably by strongly broadened claws, which are split into a high number of comb‐like teeth, perfectly matching the diameter of the bee hairs. Based on microscopy observations, both the morphology and material composition of the tarsi of B. coeca are characterized in detail. Using high‐speed video analysis, we combine the morphology data on the attachment system with a behavioural context. Furthermore, we directly measured the attachment forces generated by the bee lice in contact with the host. In particular, the claws are involved in attachment to the host, as the interstices between the teeth‐like spines allow for the collection of several hairs and generate strong friction, when the hairs slip to the narrow gap between the spines. The overall morphology of the tarsus produces strong attachment, with average safety factors (force per body weight) around 1130, and stabilizes the tarsal chain with lateral stoppers against overflexion, but also allows for the fast detachment by the tarsal chain torsion.
查看更多>>摘要：Abstract Insects control their flight toward a distant odour source by integrating multimodal sensory information, such as olfactory and visual information. Control of flight speed in orientation flight toward an odour source using visual patterning below has been observed in many species of moths. However, there are few reports about moth flight behaviour over solid‐coloured floors. To examine, which visual stimuli affect flight behaviour of moths, male smaller tea tortrix (Adoxophyes honmai) were released in a pheromone plume over two striped floors (longitudinal and transverse stripes) and two unpatterned floors (solid white and solid black). Flight behaviours were videotaped, and upwind flight speed, height (altitude) and the number of backward movements moths made as they approached the pheromone source were determined. Male moths significantly increased mean and maximum upwind flight speed over longitudinal stripes relative to their speed over transverse stripes. Their speed over a solid black floor was the fastest of all floor patterns tested. As males approached the pheromone source, their mean upwind speed decreased significantly over all floor patterns, except for the black floor. Fewer moths made backward movements over the black floor compared with the other three floors. In addition, male moths flew significantly higher over the white floor than over the other three floors, while 60–40?cm from the pheromone source. This is the first time that differences in moth flight behaviour over two patternless floors have been reported. These results suggest that orientation flight behaviour of male moths is affected not only by visual patterns, but also by the reflectance or reflected wavelength spectrum of the floor.
Krzysztof MilerDaniel StecLaura PardyakAlicja Kamińska...
7页
查看更多>>摘要：Abstract Some workers of the honeybee show high alcohol dehydrogenase (ADH) levels and high resistance to the sedative effects of alcohol, yet it is unknown whether these two issues are directly related. Here we looked for a link between ADH levels and sedation latency in response to alcohol exposure. We used molecular and immunoblotting methods to investigate a possible induction of ADH production in young, ADH‐lacking workers in response to repeated ethanol vapour presentation. Although we found increased sedation latency in individuals after several ethanol encounters, this was not accompanied by detectibly increased ADH levels in such workers. The lack of ethanol‐induced ADH production indicated that it was not needed for increased coping with alcohol inebriation. In this work, we expanded current knowledge about the effects of alcohol on honeybee workers and related it to the existing literature on the subject.
查看更多>>摘要：Abstract The solitary endoparasitoid, Microplitis rufiventris Kok, attacks and can develop in the first three instars of Spodoptera littoralis (Boisd.) larvae with preference for third‐instar. We used the last three instars to show the effect of increasing superparasitization on host resistance and reproductive capacity of surviving moths of S. littoralis that had been parasitized during their newly moulted fourth, fifth and sixth instar larvae. The degree of resistance of late instars and reproductive capacity of surviving moths varied significantly as a function of both, the virulence factors (number of wasp eggs, venom and polydnavirus) and size of host instars. Increasing number of parasitism events overcame resistance in larger host instars. The host survival was increased with the host instar and decreased with the number of ovipositions, while the chances that at least one wasp emerges follow a reverse pattern. When the survived parasitized hosts were able to pupate, parasitism usually reduced their weight, but sometimes the host pupal weight was increased. Furthermore, for surviving hosts, the weight of egg masses produced in female moths, decreased with increasing superparasitization, that is, the number of ovipositions during their larval stage. The ‘threshold’ number of parasitoid eggs, which allows the development of host, accounts for three parasitoid eggs in the fourth and fifth host instar and five parasitoid eggs in the sixth instar. The survived parasitized hosts (L4–L6) exhibited fitness‐related costs in terms of smaller size and lower reproductive output.
查看更多>>摘要：Abstract The role of desensitization in mating disruption (MD) of European Grapevine Moth (EGVM), Lobesia botrana (Dennis and Schiffermüller) (Lepidoptera: Tortricidae), is studied by exposing males to different airborne pheromone concentrations for various time intervals prior to evaluate their behavioural response. By using different types of dispensers, male moths are exposed to three decreasing pheromone concentrations (up to the minimum concentration able to desensitize them) for 1, 3, and 24?h. The airborne pheromone concentration present in all treatments is accurately quantified using gas chromatography–mass spectrometry equipment to compare these data with actual airborne pheromone concentrations under field conditions. The effect of pheromone exposure on L. botrana males is studied in wind tunnel and electroantennogram assays, immediately and 24?h after the exposure period. Results show that the reduction of response to the pheromone depended on the dose and the duration of the treatment, but the lowest dose tested did not produce desensitization. These results support that the most important mechanisms of MD acting in fields treated against EGVM are the competitive ones and that the non‐competitive ones only may become relevant very close to pheromone dispensers. Our results support the hypothesis of cross‐adaptation to other chemical stimuli in the pre‐exposed moths to their pheromone although more studies are needed to draw stronger conclusions.
查看更多>>摘要：Abstract The cypress jewel beetle, Ovalisia festiva L. (Coleoptera: Buprestidae, Chrysochroinae), and the cypress bark beetle, Phloeosinus aubei Perris (Coleoptera: Curculionidae, Scolytinae), are invasive wood‐boring pests of scale‐leafed conifers (Cupressaceae), threatening tree nurseries and urban green areas. In order to reveal which volatile compounds of their common host, the American arborvitae, Thuja occidentalis L. cultivar ‘Smaragd’, they can perceive, we collected headspace volatiles from live attached twigs and screened them for bioactivity by gas chromatography coupled to an electroantennographic detector (GC‐EAD). Compounds eliciting antennal responses were identified by gas chromatography coupled to mass spectroscopy (GC‐MS). Synthetic samples of bioactive compounds were then screened by electroantennography. GC‐EAD analyses of volatile collections revealed that E–β–caryophyllene elicited antennal responses only from O. festiva (from both sexes), whereas borneol only from P. aubei. Electroantennography screening of synthetic compounds showed further differences between the two species. Even many of those compounds, which elicited responses from both species, differed in the relative intensities of responses they evoked. This indicates that O. festiva and P. aubei probably use different key compounds in the Thuja volatile blend for host recognition.
NSTL
Wiley