Entomologia Experimentalis et Applicata最新文献

Many invertebrates and vertebrates secrete mucus from their body surface, which plays a crucial role in protecting themselves from attacks by microorganism or predators. This study reports on the potential functions of mucus secreted from the body surface of larvae of the moth Phauda flammans (Walker) (Lepidoptera: Phaudidae). We tested whether the mucus could inhibit the growth of the fungus Beauveria bassiana PfBb (Bals.-Criv.) Vuill. (Hypocreales) and attract and/or deter predators such as the crazy ant, Paratrechina longicornis (Latreille) (Hymenoptera: Formicidae), and the predatory bug Eocanthecona furcellata (Wolff) (Hemiptera: Pentatomidae). Our results showed that de- and rehydrated mucus concentrations of 0.5–1.0 mg mL⁻¹ had an inhibitory effect on the conidial germination and colony growth of B. bassiana PfBb; however, P. flammans mucus did not significantly affect fungal sporulation. Raw mucus and mucus concentrations of 1.0–4.0 mg mL⁻¹ attracted P. longicornis workers in a Y-tube olfactometer, whereas the physical viscosity of raw mucus hindered their foraging for food in a laboratory test. The E. furcellata adults did not display a preference for the odour of P. flammans mucus. Therefore, P. flammans mucus may inhibit pathogenic microorganisms and attract or repel predators, but the mucus does not act as a complete deterrent.

Perina nuda (Fabricius) (Lepidoptera: Lymantriidae) is an important leaf-feeding pest of Ficus species. It significantly affects the growth and reproduction of Ficus species, the economic prospects of growers, and the beauty of urban gardens. This study employed the MaxEnt model to predict and analyze the potential distribution of P. nuda in China, utilizing global distribution data and the correlation between the distribution of P. nuda and environmental variables. The results showed that the dominant environmental variables influencing the distribution of P. nuda included the warmest quarterly precipitation, coldest monthly minimum temperature, annual precipitation, and wettest monthly precipitation. The potential distribution area of P. nuda in China under current climatic conditions is 158 × 10⁴ km², accounting for 16.4% of the total area of the country. According to the SSP5-8.5 scenario in 2050, the potential distribution area of P. nuda is projected to reach 200 × 10⁴ km², an increase of 26.5% compared to the current. P. nuda is widespread in China and has a tendency to spread, threatening the growth of Ficus species. This study is important for monitoring and control of P. nuda in areas where it is present, and where it may be present in the future.

Pathogen infection and conspecific density may considerably affect key life-history traits of organisms. For naturally aggregating species, even low concentrations of pathogens or high larval densities may have detrimental effects. However, the detailed influence of these factors, particularly their interaction effect, is often overlooked in ecological and life-history studies. To investigate the effects of conspecific density and pathogen infection on life-history traits, we explored the influence of larval density (1 and 5 larvae cm⁻², i.e., low and high density, respectively) on phenoloxidase (PO) activity, body mass, and development time of Hermetia illucens L. (Diptera: Stratiomyidae) larvae in the presence of two strains of the entomopathogenic fungus (EPF) Beauveria bassiana (Bals.-Criv.) Vuill. We observed higher PO activity in EPF-treated larvae than in the untreated control and a pronounced difference in PO activity between the two EPF-strain treatments. Larvae reared at high density and treated with EPF showed higher PO activity than untreated larvae at low density. The EPF-treated larvae and larvae reared at high density had longer larval periods than untreated larvae and larvae reared at low density, respectively. Larvae reared at high density also achieved reduced prepupal and pupal masses compared to conspecifics at low density. Interestingly, untreated larvae only achieved higher prepupal and pupal masses at low density, whereas at high density, the pattern was reversed (treated individuals had higher pupal masses). Overall, our results demonstrate that high density and fungal pathogens both induce a higher immune response compared to low density and pathogen-free environments, but this comes with a cost of a longer larval period and reduced body mass.

Predaceous diving beetle adults scavenge for carrion in freshwater habitats. We identified two scavenging strategies used by adult Dytiscus sinensis Feng (Coleoptera: Dytiscidae) to locate and consume food at the bottom of water when needing to surface for air store renewal: dine-in then relocate the food (dine-in strategy) and carry the food to the surface (take-away strategy). In 5-cm-deep water, a higher proportion of individuals successfully located food within an 8-min test window than in 25-cm-deep water. Their latencies to locating food did not differ among depths. Dytiscus sinensis adults preferred the take-away strategy in 5-cm-deep water and a higher proportion of them adopted the dine-in strategy in 25-cm-deep water. Further, a 10-cm-deep test showed that the success rate or efficiency of relocating food did not increase with the experience of locating it the first time. This might explain why D. sinensis preferred the take-away strategy in shallower water, in which it had lower risks of losing the food. The present study revealed a direct bottom-up benefit for dytiscids foraging in shallower water where finding and securing food were easier. Our findings demonstrate that the surfacing requirement of dytiscid adults was reflected in foraging strategies with depth-dependent preferences.

Lady beetles (Coleoptera: Coccinellidae) are important biocontrol agents that are considered generalist predators, although some tribes, such as Scymnini, are specialized in predation of sucking pests, such as mealybugs, aphids, and whiteflies. However, prey preference or pre-imaginal conditioning may occur as coccinellids are subjected to large-scale rearing. Thus, predator–prey interaction may be an outcome of conditioning to prey stimuli. To evaluate possible pre-imaginal conditioning, population lines were created for the lady beetles Cryptolaemus montrouzieri Mulsant and Tenuisvalvae notata (Mulsant), each fed for at least eight generations the mealybugs Ferrisia dasylirii (Cockrell) or Planococcus citri Risso (Hemiptera: Pseudococcidae). Next, the behavioral response of these coccinellids was measured in arenas treated with prey volatiles or footprints, regarding walking time, walking speed, walking distance, and residence time. Finally, food preference between prey species was measured in laboratory and semi-field conditions on infested cotton plants. Conditioned coccinellids responded similarly to volatiles released by either prey species offered. Furthermore, there were no changes in predator behavior towards footprints of either prey species. Both predator species consumed more P. citri in all tests, regardless of rearing prey indicating no pre-imaginal conditioning. These results suggest that rearing prey may not affect the predator behavior, and both coccinellid species are effective in the biological control of mealybugs.

This special issue comprises papers presented at the 7th International Entomophagous Insects Conference (IEIC7), in Buenos Aires, Argentina, in 2023. Entomophagous insects, which prey on or parasitize other insects, play a pivotal role in ecosystems and are widely utilized as biocontrol agents. This special issue includes two review articles and nine research papers covering diverse subjects such as ecology, physiology, behavior, genetics, chemical ecology, and biological control, which reflects the diversity of topics presented and discussed during the conference.

Continued use and development of new insecticides are seen as a necessary part of modern agriculture, but insecticides, even at sublethal levels, may also affect beneficial non-target species, such as pollinators, predators, and parasitic wasps. Here, we studied sublethal effects of four insecticides – acetamiprid, dimethoate, flupyradifurone, and sulfoxaflor – all targeting cholinergic neurons in insects, on sexual communication and olfactory host finding in the parasitic wasp Lariophagus distinguendus (Förster) (Hymenoptera: Pteromalidae). We found that all four insecticides reduced, at least at one of the tested sublethal doses, pheromone-mediated courtship behaviour (wing fanning) in males and the mating frequency of treated wasps. Treated females no longer preferred host-associated kairomones. This suggests that the olfactory sense of the wasps is hampered by sublethal insecticide doses. The lowest bioactive doses tested in the bioassays were 0.021 ng for sulfoxaflor and 0.105 ng for acetamiprid, dimethoate, and flupyradifurone. These low amounts are field realistic and might be taken up by the wasps, e.g., by feeding contaminated plant nectar. Exposure to these compounds likely compromises the important ecosystem service provided by parasitic wasps as natural enemies in terrestrial ecosystems.

Shelf life is an important determinant of the quality of parasitoids used as natural enemies in augmentation biological control. Cotesia chilonis (Munakata) (Hymenoptera: Braconidae), an obligate endoparasitoid of Chilo suppressalis (Walker) (Lepidoptera: Crambidae), has potential for use through augmentation biological control in China. Here, the effects of cold storage temperature, host status, and larval stage on the biological characteristics of C. chilonis were investigated to extend the agent's shelf life. Results showed that the number of healthy C. chilonis adults obtained was reduced by 3.5% and 47.7% when C. suppressalis larvae in either natural or induced diapause were used as hosts compared to nondiapausing control larvae. Both parasitism and cold storage significantly reduced the supercooling point of nondiapausing C. suppressalis larvae, whereas the opposite result was observed in those of natural diapause. In order to improve the long-term storage of C. chilonis, nondiapausing C. suppressalis larvae were parasitized for 1, 3, 5, and 7 days to allow C. chilonis to develop into different larval stages before being transferred into cold storage for 30 days at 4 or 10°C. Compared to the control, the C. chilonis cocoon formation and emergence rates of the 1-day-old egg treatment group held at 10°C were reduced by 15% and 17%, respectively. The results also showed that the duration of the larval stage of C. chilonis was prolonged fourfold after storage at 4 and 10°C. Individuals held at 10°C had a significantly longer cocoon and adult stage compared to those held at 4°C. The biological parameters and life history of the F₁ generation of C. chilonis returned to normal levels under laboratory conditions. In conclusion, C. suppressalis larvae were successfully used to extend the shelf life of C. chilonis for use in augmentative biocontrol programs.

The electrical penetration graph (EPG) allows researchers to obtain information on the feeding behavior of herbivorous piercing–sucking insects, mostly Hemiptera. Guidelines are proposed for designing and conducting EPG experiments on insect–plant interactions, and for analyzing and interpreting the data. Several statistical issues common in EPG experiments are discussed. Pre-recording insect handling, wiring, and being tethered can affect feeding behavior and recommendations are made to minimize such stresses. Recording duration can have a large effect on some variables and interpretation of the data. The pros and cons of long vs. short recording duration are discussed, and suggestions are made for reconciling these conflicting concerns. Replicates lacking a specific waveform pose problems for analyzing variables associated with that waveform. Proper ways for handling these replicates when analyzing data are discussed. The waveform in progress when the recording ends will be terminated before it would naturally end; consequently, its duration will be artificially short (truncated). This creates a problem for calculating mean or median duration of waveform periods (a waveform period is a single occurrence of the waveform), especially for waveforms that tend to occur relatively few times during a recording and in long periods, such as waveforms E2 and G (phloem and xylem sap ingestion for aphids) or Xi (xylem sap ingestion for xylem feeders). Based on a detailed analysis (see the supporting information), guidance is given on how to calculate mean and median duration of waveform periods when the last period is truncated. A modified experimental design is suggested to avoid the problem of truncated waveform periods. Most EPG variables are interdependent, and their values can affect one another. This interdependence should be considered when drawing conclusions from the data. In studies on plant resistance against vascular sap-feeders, variables that are associated with resistance encountered during the penetration route to the vascular tissue and those encountered in the vascular tissue are discussed.

Fruit and vegetable crops are affected by numerous arthropods, including aphids and thrips. Hoverfly adults are important pollinators, and their larvae are mainly aphid predators. Molecular studies on the stomach contents of larvae allowed to associate hoverflies with the consumption of other soft-bodied arthropods, including thrips, with few records found in Neotropical hoverfly species. Allograpta exotica (Wiedemann) (Diptera: Syrphidae), a species widely distributed in the Americas, from the USA to Argentinian Patagonia, has been associated with numerous crops mainly affected by aphids, and to a lesser extent with whiteflies. The objective of this work was to assess the consumption and preference rates of various instars of A. exotica as biocontrol agents for two major insect pests, Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Frankliniella gemina (Bagnall) (Thysanoptera: Thripidae), under controlled laboratory conditions. Additionally, we morphologically characterized the three larval stages of A. exotica. We determined that all three instars of A. exotica consume both M. persicae and F. gemina, and that they kill more thrips than aphids. Still, A. exotica preferred M. persicae over F. gemina, even when the relative aphid availability decreased compared to F. gemina, although consumption of both prey types remained high. Interestingly, A. exotica second instars consumed four times more thrips than aphids. This study explored the potential use of one of the most common hoverfly species in fruit and vegetable crops as a biocontrol agent of aphids and thrips. Further laboratory and field studies should explore more deeply the potential of this Neotropical beneficial dipteran.