Entomologia Experimentalis et Applicata最新文献

Dietary generalist herbivorous insects are widespread and often occur in a variety of environments. Across their geographic range, herbivorous insects may encounter variable plant traits as they feed on high-quality or low-quality plants. Herbivorous insect larvae experience both bottom-up (host plant) and top-down (parasitoid) factors that affect survival. Host plant quality may affect larval growth and survival in that larvae feeding on low-quality plants often suffer reduced fitness. However, herbivores on different host plants are also subject to different levels of parasitism. High-quality plants confer stronger larval performance (higher survival, more offspring), but larvae may also face higher parasitism. In some herbivore species, diet mediates larval immune response. The generalist insect herbivore fall webworm (FW), Hyphantria cunea Drury (Lepidoptera: Erebidae), is a moth native to North America, and its larvae have considerable variance in their performance when reared on different host plants. We investigated whether diet affects the immune response in FW larvae when they are reared on different host plant species known to vary in food quality. We measured immune response by melanization of a nylon filament. We found significant differences in immune response across host plants, indicating that diet mediates immune response in FW larvae. Our study helps elucidate the factors that cause variation in immune response in a generalist herbivore.

Substrate-borne vibrations are ubiquitous in nature and are used by diverse taxa to communicate and to obtain information about their environments. However, substrate-borne vibrations remain understudied compared with other sensory and signaling modalities, in part due to human sensory biases. In addition, understanding and quantifying the transmission of vibrations remains a challenging task due to it being dependent on both signal properties and properties of the substrates that the signals transmit through. Here, we provide methods for playing back and measuring the transmission of vibrations throughout a substrate. Using linear resonant actuators, we conducted playbacks of pure tones and frequency sweeps on wooden dowels and on the stems of potted Ptelea trifoliata L. (Rutaceae) plants. We used scanning laser Doppler vibrometry to measure the signals at multiple locations along the length of the dowels and plant stems. We demonstrate that playback of a frequency sweep yields more data in a shorter amount of time than multiple playbacks and measurements of pure tone signals. Our results are also consistent with previous findings showing that signals produce frequency and location specific minima and maxima (nodes and antinodes) throughout the substrates, rather than simply attenuating with distance. This results in filtering of signals, such that their spectra are unique at any given measurement location—illustrating the importance of measuring vibrations at multiple locations. We discuss the implications of such filtering phenomena for vibrationally signaling animals and the biotremologists that study them.

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are of huge veterinary importance, mainly as vectors of pathogens, such as Bluetongue virus. Currently, there are no effective methods to protect animals against biting midges, as insecticides have limited or short-lived efficacy. Biting midges are attracted to hosts by carbon dioxide and by their body odours, which are mainly produced by skin bacteria. In humans, it has been shown that differences between individuals in attractiveness to mosquitoes is mediated by these skin bacterial volatiles. This opens the possibility to protect individuals from biting insects by supplementing their skin microbiome with probiotics. In this study, we investigated this approach by culturing sheep skin bacteria on various media and assessing their effects against field-caught Culicoides (overwhelmingly Obsoletus group species) as well as laboratory-reared Culicoides nubeculosus (Meigen). Aerococcus urinaeequi, Bacillus safensis, Bacillus subtilis, Jeotgalicoccus psychrophilus, Micrococcus sp. and Staphylococcus equorum were selected to be tested in a dual-choice Y-tube olfactometer, assessing their behavioural effects on biting midges. We revealed an avoidance effect on laboratory-reared C. nubeculosus when testing B. safensis and B. subtilis. Bacillus safensis and Micrococcus sp. yielded significant repellent potential towards field-caught Culicoides. These two candidates were subsequently tested in a membrane blood-feeding assay. When the bacterial species B. safensis was applied to the membrane, a feeding reduction of 83% was observed with field-caught Culicoides.

Predation exerts a profound influence on the evolution of camouflage and detection abilities in both predators and prey. For instance, flower-visiting spiders need to ensure their concealment when ambushing on flowers, which compels pollinators to check any spider cues cautiously before landing. Although numerous studies have examined the visual camouflage of spiders deceiving bees, little is known regarding whether spiders also employ olfactory camouflage. Additionally, the detection of spiders by dipteran insects is often overlooked, despite them being major non-bee pollinators. Here, we explored the detection ability of dipteran pollinators and the crypsis skill of spiders from both olfactory and vision perspectives using the housefly Musca domestica L. (Diptera: Muscidae) as prey, the crab spider Ebrechtella tricuspidata (Fabricius) (Araneae: Thomisidae) as predators and chamomile Matricaria recutita L. (Asteraceae) as substrates. Our olfactory experiments revealed that experienced houseflies could respond to and avoid spider odour. However, this response did not appear to be innate, as naive individuals showed no aversion. Moreover, experienced houseflies did not have any avoidance behaviours to the mixed odours of spider and flower, indicating that spiders achieved olfactory crypsis utilizing floral scent. Our vision experiments and visual modelling demonstrated that houseflies could detect spiders positioned on flower. Surprisingly, instead of avoiding them, houseflies exhibited a preference for flowers occupied by female spiders, suggesting the attractive nature of female spider colouration. This paper provides evidence for the first time that crab spiders use floral scent to achieve olfactory crypsis and proposes a potential yellow-signalling mechanism for crab spiders to attract insects.

Several European and North American countries have started releasing the Japanese knotweed psyllid, Aphalara itadori (Shinji) (Hemiptera: Aphalaridae), to control the Japanese knotweed, Reynoutria japonica Houtt. (Polygonaceae), and its relatives, which are among the worst invasive exotic plants. However, establishing populations of the currently released strains in the field has not been successful, desiring newly collected lineages. Moreover, little is known about the microbiome of the current strains, which potentially impacts properties as biocontrol agents. Hence, this study analyzed the microbiota of an A. itadori strain newly collected on Honshu Island, Japan, along with related species of the family Aphalaridae, using amplicon sequencing of 16S rRNA genes. The localization of symbionts identified in A. itadori was further analyzed using fluorescence in situ hybridization. The results demonstrated that the A. itadori bacteriome, a specialized organ for microbial symbiosis, maintains a dual symbiotic system with the primary symbiont “Candidatus Carsonella ruddii” (Gammaproteobacteria: Oceanospirillales: Halomonadaceae) and the secondary symbiont Sodalis sp. (Gammaproteobacteria: Enterobacterales: Pectobacteriaceae), suggesting that they are evolutionarily stable obligate mutualists for A. itadori. The central area of the bacteriome containing Sodalis comprised uninucleate bacteriocytes with nuclei larger than those of bacteriocytes harboring Carsonella. This observation contrasted previous reports on various psyllid lineages in which secondary symbionts are housed in a central syncytium with nuclei smaller than those of bacteriocytes for Carsonella. No known plant pathogens or parasitic manipulators of insect reproduction were identified in the analyzed A. itadori strain, indicating its suitability as a biocontrol agent, posing a minimum risk to the ecosystem. Besides distinct Carsonella lineages, Sodalis independently acquired by Craspedolepta miyatakeai Klimaszewski and an ambiguous Enterobacterales symbiont in Epheloscyta kalopanacis Loginova were identified. Only Carsonella was found in Togepsylla matsumurana Kuwayama. These results indicate repeated infections and replacements of bacterial symbionts during the evolution of Psylloidea, providing deeper insights into the microbe-psyllid interactions.

Black soldier fly larva (BSFL), Hermetia illucens (L.) (Diptera: Stratiomyidae), presents an attractive waste management solution that not only addresses the issue of waste but also generates alternative proteins and fats. Substrate quality and pre-treatment by fermentation may play a crucial role in waste reduction efficiency and larval quality. The aim of this study was to investigate the growth performance, waste reduction efficiency and nutritional composition of BSFL rearing using different ratios of coconut endosperm (CE) and soybean curd residue (SC) with pre-treatment by self-fermentation (F), fermentation with baker's yeast (Y) and without pre-treatment (C). Seven-day-old larvae were randomly separated into 15 experimental groups with three replicates. The experiment ended when the prepupae appeared. Based on the results, the larvae fed a diet with a high percentage of fresh SC exhibited the highest weight and growth rate, whereas the shortest development time was observed in larvae reared on Y. Pre-treatment of the substrate with fermentation proved effective in waste reduction. The nutritional composition of the larvae showed that the highest crude protein was produced in larva reared on fresh 100% SC, and the highest ether extract was found when fed CE at 100% with pre-treatment with F or Y. In conclusion, it is recommended to employ a fresh diet with a high SC content to optimise protein production, whereas a high level of CE with F or Y may be performed to obtain a high ether extract content. However, incorporating yeast fermentation with an SC content exceeding 25% provided high efficiency in waste reduction. Therefore, the selection of the ratio between CE and SC and of pre-treatment techniques depends on the producer's objective.

To be effective, a biocontrol agent must survive and persist in the same habitat as the target species and reduce target population growth. When multiple biocontrol agents are used against a single invasive species, they may each perform better under a subset of the habitat in which the target lives. This complementarity allows for a more consistent level of control and a higher resilience to environmental variability. Two species that feed on the same plant tissues would compete, but niche partitioning in the native range may be replicated when both species are introduced to the invasive range. When biocontrol agents are released, they may self-sort to perform best in their respective niches. We hypothesized that two biocontrol agents—Scotch broom seed beetle, Bruchidius villosus (Fabricius) (Coleoptera: Chrysomelidae) and Scotch broom seed weevil, Exapion fuscirostre (Fabricius) (Coleoptera: Brentidae)—that both feed on seeds of the invasive legume Scotch broom, Cytisus scoparius L. Link (Fabaceae), would be impacted differently by different weather conditions and plant traits, and would show different success rates at field sites with different conditions. We used a 5-year study to reveal that the two biocontrol agents are not uniformly distributed in the field and that weather and plant factors influence their success. We confirmed that weather conditions of the previous year influenced biocontrol agent attack rate and found that weather patterns at a field site may predict the impact of each biocontrol agent.

Factors that mediate insect herbivore sabotaging behaviour of host plant latex defences remain under debate. The most prominent hypothesis suggests that the anatomy of the host plant's laticifers determines trenching or vein-cutting behaviour, but there are inconsistencies in the literature. In addition to latex, other plant defences have been shown to affect plant natural enemies, but experimental studies comparing the effects of multiple defences on herbivore performance and behaviour are scarce. In this study, we investigated the anatomy of the laticifers of Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), an exotic milkweed of southeastern Brazil, as well as the sabotaging behaviour of larvae of southern monarch, Danaus erippus (Cramer), and queen butterfly, Danaus gilippus (Cramer) (Lepidoptera: Nymphalidae) on this host plant. We also reviewed the sabotaging behaviour of larvae reared on the native milkweed Asclepias curassavica L. (Apocynaceae) from previous studies, as well as the description of the anatomy of its laticifers. As we found no correspondence between sabotaging behaviour of southern monarchs and queens and the anatomy of the host plants' laticifers, we tested whether structural defences of C. procera leaves (latex, waxes and trichomes) affected sabotaging behaviour and larval performance of southern monarch larvae. The structural barriers of this well-defended host affected larvae in different ways: Southern monarchs developed more slowly on control leaves than on leaves from which wax had been removed, and only latex removal reduced the frequency of sabotaging behaviour. Regardless of the defence removal treatment, frequencies of trenching behaviour decreased and vein-cutting behaviour increased as larvae developed. Overall, our results show that several factors in addition to the anatomy of laticifers affect sabotaging behaviour of southern monarchs and queens, including larval ontogeny, danaine species and latex outflow. This evidence suggests a behavioural plasticity in the sabotaging behaviour of larvae of both southern monarchs and queens.

Arthropods in the spotlight – identifying predators of vineyard pest insects with infrared photography – J. M. Reiff, K. Theiss, C. Hoffmann & M. H. Entling (https://doi.org/10.1111/eea.13456).

Artificial selection of zoophagous lines of the biological control agent Dicyphus hesperus - F. Dumont, M. Solà Cassi, M. Lemay & C. Provost (https://doi.org/10.1111/eea.13483).