Entomologia Experimentalis et Applicata最新文献

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.

Multitrophic interactions are common in nature and play a major role in modulating life-history traits in predatory insects. The sequestration of chemicals and the transfer of nutrients from one trophic level to a higher trophic level have been reported previously. However, the effect of cannibalism, which is prevalent in the food chain, has not been explored yet. In this study, we hypothesised that the varying nutritional condition of the victim would significantly influence the life-history traits of adult Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae). To test this hypothesis, we provided fourth-instar individuals with first-instar victims of varying nutritional quality for cannibalism. To create victims of varying nutritional quality, first-instar victims were fed on high-quality aphids [Aphis craccivora Koch (Hemiptera: Aphididae)], low-quality aphids (Aphis nerii Boyer de Fonscolombe) and conspecific eggs. The cannibalistic groups were tested against the control group, in which the fourth instars were provided with their natural prey, A. craccivora. Our results revealed a significant difference in the consumption of prey by the fourth instars between the diet groups, with the control group consuming the most prey. The developmental duration of fourth instars was not significantly influenced by the victims' diet or the amount of victims cannibalised. Furthermore, neither the victims' diet nor the amount of victims cannibalised affected the mating (time to commence mating and copulation duration) and reproductive parameters (egg viability and fecundity) in M. sexmaculatus. Cannibalism here might have compensated for the low-quality victims, resulting in insignificant effects on the life-history traits of M. sexmaculatus. Otherwise, given the short duration of the first instars and their potentially limited ability to sequester significant amounts of plant allelochemicals, it is possible that their diet did not affect the development, mating and reproductive attributes of the cannibals. Thus, the use of higher instars as victims may yield substantially different outcomes.

Native parasitoids are potential tools for the biological control of invasive exotic pests, such as the frugivorous flies spotted-wing drosophila, Drosophila suzukii Matsumura, and African fig fly, Zaprionus indianus Gupta (both Diptera: Drosophilidae). Following biological invasions, the establishment of exotic species may be restricted, among other things, by their susceptibility to native or established natural enemies. The Neotropical-native pupal endoparasitoid Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae), although primarily associated with hosts of the genus Anastrepha (Tephritidae), has also been described to attack Drosophilidae. There are few studies on the interaction between parasitoids native to Argentina and D. suzukii and/or Z. indianus. The present work evaluates the parasitism of T. anastrephae on both species of drosophilids under controlled conditions. Ten larvae (L3) of each host species were exposed separately to a couple of adult T. anastrephae for 72 h (n = 10). For both control and parasitoid treatment, 10 larvae (L3) of D. suzukii and Z. indianus were placed in 10 flasks (repetition) at the L3 stage. Host emergence, the infestation degree index (DI), and the parasitism success rate (SP) were calculated. Drosophila suzukii and Z. indianus emergence differed significantly in controlled conditions being 41% higher for Z. indianus than for D. suzukii. The DI was 100% in D. suzukii and 38% in Z. indianus, and the SP was 48% both in D. suzukii and in Z. indianus. These findings indicate that the native parasitoid T. anastrephae has a high potential as a biocontrol strategy against D. suzukii. In addition, the efficiency of T. anastrephae against Z. indianus, an invasive frugivorous widely spread in the Neotropical region, was evaluated for the first time.

Sampling nests of yellow jackets, Vespula spp. (Hymenoptera: Vespidae), represent a particular challenge due to the danger involved in working with live colonies of a potentially aggressive venomous super-organism. Here, we report on sampling methods using a petrol-driven leaf blower/vacuum and a battery-powered vacuum to sample returning Vespula germanica (Fabricius) foragers at their nest entrance. These methods make the sampling of returning foragers at the nest more efficient and convenient and represent a low-risk approach to sampling. Applications include prey analysis and genetic sampling that can be done destructively or non-destructively depending on the geographic location. We sampled 15 nests using the two-stroke vacuum apparatus and collected on average (±SD) 454 ± 271 wasps per nest. We believe that the petrol-driven vacuum collection apparatus we designed is a useful method for collecting a large number of social wasp foragers returning to a single-nest entrance.