Physiological Entomology最新文献

The present research investigates host preferences and larval development of the melon ladybird Chnootriba elaterii (Rossi) (Coleoptera: Coccinellidae), considering seven Cucurbitaceae plant species (Citrullus lanatus, Cucumis melo, Cucumis sativus, Cucurbita pepo, Cucurbita moschata, Lagenaria siceraria and Luffa aegyptiaca), to determine whether mother host preference is related with larval performance. The damaged area on plant leaves due to insect feeding in dual-choice experiments was used to evaluate food preferences. Behavioural experiments in a Y-tube olfactometer tested the role of olfaction in host-plant selection. Parameters such as development duration and morphometric characters of emerged adults were evaluated to estimate larval performance. Adult females selected watermelon and melon as their favourite food while firmly refusing loofah and calabash. Insects preferred melon over watermelon, but the larval development on melon was slower; moreover, watermelon allowed larvae to develop faster than other tested plants, while loofah did not allow larval development. Larvae fed and developed on melon, pumpkin, zucchini, cucumber and calabash, without strong differences. These results only partially supported the preference-performance hypothesis suggesting that it could be context dependent. Contrary to expectation, volatile organic compounds (VOCs) belonging to the host, only partially could guide adult females in the olfactometer. This result suggests that long-distance olfactory stimuli alone cannot provide sufficient information for host-plant selection in melon ladybirds. Considering the economic relevance of C. elaterii, the results of the present paper answer some basic questions about host-plant selection for this pest insect, potentially useful to improve control strategies in crops.

Flower nectar, a sugar-rich solution containing amino acids as major secondary solutes, is the primary energy source for bees. Proline is one of the most abundant protein nectar amino acids, showing several effects on bee physiology. Mason bees are outstanding pollinators, often preferred to Apis mellifera for pollination of fruit trees. Among them, Osmia cornuta (Latreille) is one of the most successfully managed species on a commercial scale. In this work, the effects of 10 mM proline-enriched diet administration on O. cornuta feed consumption, survival, behaviour and haemolymph amino acid composition were investigated. Feed intake was higher for the proline diet, while survival rate was not affected. Behaviour was affected only in the senescence of the mason bees with a reduction in locomotor activity induced by proline intake. Proline diet also affected the haemolymph amino acid composition, decreasing concentration of tyrosine, methionine, leucine and phenylalanine after 10 days of feeding. These results were discussed in relation to the potential involvement of proline in oxidative stress in insects and proline's ability to be converted to other amino acids. Further investigations are necessary to better understand the molecular mechanisms of proline effects on locomotion and oxidative stress.

Recently, neuropeptide F2 (NPF2) has been demonstrated to increase food consumption and body weight in the cotton bollworm, Helicoverpa armigera. This study evaluated the effect of NPF2 on the adult female reproductive system of H. armigera. Daily NPF2 injections increased oocyte size, ecdysteroid titre in ovaries and haemolymph and the expression level of ecdysone receptor (EcR), ultraspiracle (USP) and vitellogenin (Vg) genes. However, NPF2 injection had no effect on the expression level of hormone receptor 3 (HR3). Fecundity and fertility were increased after the injection of NPF2. The knockdown of the NPF2 gene using RNA interference (RNAi) had opposite effects compared to NPF2 injection. Overall, these results revealed that NPF2 has a regulatory role in the female reproduction of the cotton bollworm.

Acetylcholinesterase (AChE) is a promising enzyme and a biomarker to monitor the physiological status of honey bees. To gain a basic understanding of AChE in bees, we measured AChE activity in the head tissue of forager honey bees belonging to Apis cerana, Apis mellifera, and Apis dorsata collected from five districts of Nepal during pre-winter and winter seasons. We estimated AChE-tissue activity (μmol/min/g head tissue) and AChE-specific activity (μmol/min/mg protein) using Ellman assay kit and protein concentration (mg/g head tissue) using Lowry assay method. A significant increase in all three parameters was observed in winter A. cerana and varied between species indicating differences in physiological resistance and responses to various environmental changes between native (A. cerana and A. dorsata) and non-native (A. mellifera) bees. Overall, AChE-tissue and specific activities were positively correlated and, as expected, AChE-specific activity was negatively correlated with the protein concentration.

Required sample sizes for a study need to be carefully assessed to account for logistics, cost, ethics and statistical rigour. For example, many studies have shown that methodological variations can impact the critical thermal limits (CTLs) recorded for a species, although studies on the impact of sample size on these measures are lacking. Here, we present ThermalSampleR; an R CRAN package and Shiny application that can assist researchers in determining when adequate sample sizes have been reached for their data. The method is particularly useful because it is not taxon specific. The Shiny application offers a user-friendly interface equivalent to the package for users not familiar with R programming. ThermalSampleR is accompanied by an in-built example dataset, which we use to guide the user through the workflow with a fully worked tutorial.