Entomologia Experimentalis et Applicata最新文献

Light-emitting diode traps in commercial greenhouses: A field study report on Encarsia formosa bycatch—B. Grupe & R. Meyhöfer (https://doi.org/10.1111/eea.13521).

The larvae of black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), are an excellent source of feed for animals and have emerged as a promising candidate for waste disposal. The larval growth can be impacted by the intake of heavy metals. However, the underlying mechanism for metal tolerance of the gut microbiome is still poorly understood, as well as how heavy metals, especially in combination, affect the communities of bacteria in the larval gut. Therefore, in this study we focus on how Cu and Zn affect larval growth and gut microbiome, as well as how bioaccumulated heavy metals are distributed in larval residues and bodies. The larval biomass growth was both significantly improved and inhibited by exposure to low and high Cu and Zn concentration, respectively, including in combination. The amount of accumulated Cu and Zn in larval residues and bodies significantly increases as the exposure concentration is increased. In larval bodies, Zn was more likely to be accumulated (57.2%–78.5%) than Cu (<40%). More importantly, the larval gut microbiome was found to be remarkably altered by Cu and Zn exposure, particularly for species of the phyla Actinobacteria, Bacteroidetes, and Firmicutes. In addition, with the exception of the Cu at 400 mg kg⁻¹ exposure, the diversity and complexity of the gut bacterial community significantly decreased. Functional genes related to heavy metal resistance and transport, such as pcoB, pcoD, copC, pccA, ABC.ZM.S, and yahk, were clearly enriched in the larval gut, which may help to partly account for the ability of black soldier fly larvae to tolerate metals.

Honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies and individuals respond variably to disturbances. The response depends on perception and interpretation of stimuli requiring both neural modulation and use of energy. In this study, we examined the role of neural modulation and brain metabolism in constitutive and experience-dependent differences in defensive response. For constitutive differences, we compared brain gene expression in bees from gentle and defensive colonies identified in a standard colony-level assay. For experience-dependent changes in defensiveness response, we compared brain gene expression in control bees and bees that responded by sting extension to electric shock in a standardized individual behavioral assay. In both experiments, for neuromodulation, we examined membrane receptor genes for the biogenic amines dopamine (DopR2), octopamine (OA1), and serotonin (5HT2a), as well the gene for the enzyme responsible for serotonin synthesis (THR). For neural metabolism, we examined the expression of two Oxidative Phosphorylation Pathway “OXPHOS” genes (ND51 and ND20-LIKE). Bees collected from defensive colonies had a significantly lower expression of amine receptor, synthesis gene, and OXPHOS genes. However, bees responding to noxious stimuli (i.e., electric shock) showed greater gene expression for both OXPHOS and neuromodulation genes, except for 5HT2a. We discuss the intriguing intersection of neuromodulation and neural metabolism in defensive response both for constitutive differences, and contrasting experience dependent or adaptive differences.

Monitoring pollinating arthropods in crop systems can provide important information about pollinator populations and potential yield but can be hampered by accessibility to flowers in some systems, or by the timing of flowering and pollinator visits. This is particularly the case in oil palm, the world's leading source of vegetable oil, where flowering is discontinuous, inflorescences are sometimes many metres off the ground, and pollination is largely dependent on a single insect species—the specialist weevil, Elaeidobius kamerunicus Faust (Coleoptera: Curculionidae). We used oil palm as a case study system to trial a new trap design to selectively survey flower-visitors of insect-pollinated crops. The trap consisted of a pan trap baited with half a male oil palm inflorescence. To assess effectiveness of the trap across different environments, we set pairs of baited and non-baited control pan traps in a variety of habitats in industrial oil palm plantations in Riau, Indonesia. We identified all arthropods collected to order level, with ants separated from other Hymenoptera owing to their distinct ecology, and E. kamerunicus identified to species level. We found a higher abundance of arthropods trapped by baited versus unbaited traps across all habitat types and across all taxa except Orthoptera, with the greatest differences found in E. kamerunicus, non-E. kamerunicus Coleoptera, Diptera and Lepidoptera. The age of inflorescences used in baited traps affected abundances of certain taxa, with 8% reduction in E. kamerunicus abundance, 1% reduction in other Coleoptera and 4% reduction in Lepidoptera with each 1% increase in inflorescence openness beyond 40% open. Most taxa were found in higher numbers in the baited traps. The baited pan traps worked across a range of habitats and present an effective and inexpensive survey method for assessing populations of flower-visiting arthropods and could collect a wider range of flower-visitors than traps baited with more specific attractants, such as estragole, a volatile component emitted by oil palm inflorescences. Similar approaches could be trialled in other insect-pollinated crops.

The plastic nutritional foundations of growth and reproduction are crucial in mediating animal (insect) life histories but remain largely unexplored. Here, we investigate how the nutritional quality of dung during larval feeding affects subsequent (adult) life history traits of a coexisting guild of four closely related European sepsid dung fly species: Sepsis cynipsea (L.), Sepsis fulgens (Meigen), Sepsis punctum (Fabricius), and Sepsis thoracica (Robineau-Desvoidy) (all Diptera: Sepsidae). Larvae were raised in standard cow dung, protein-rich (yeast-supplemented) dung, microbe-depleted (autoclaved) dung, and in a combined treatment of autoclaved dung with yeast enrichment. Responses of egg-to-adult survival, total development time, final adult body size, and female reproductive potential in terms of age at first reproduction and offspring number were assessed. Overall survival was lower in autoclaved dung, but also tended to be reduced rather than enhanced by potentially artificial microbial additives such as supplemental yeast, which apparently cannot be metabolized effortlessly by the fly larvae. The only trait positively affected was adult body size, for which we observed an increase in three of four species when larvae were raised in yeast-supplemented dung. Flies emerged smaller when reared in autoclaved dung, and the addition of yeast to autoclaved dung partly compensated the negative effect of autoclaving to result in a body size similar to control dung. Our results thus indicate that larval growth is likely reduced by autoclaving-induced killing of nutritional microorganisms in the dung, which however may recolonize. Whereas for some model insects nutrition is well-understood, more research is necessary to unravel the diverse effects of natural and artificial stressors on the nutrition of non-model insects, such as these dung-decomposing flies providing important ecosystem services in human-mediated grasslands.

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a highly destructive agricultural pest. The ability of S. frugiperda to survive and reproduce is widely recognized, but it is also important to consider the role of larval cannibalism as a significant biological trait. Understanding the cannibalistic habits of pests helps to explore the dynamics and evolution of their populations and facilitates the monitoring of insect outbreaks. Therefore, the stages, densities, and intensity of cannibalism in S. frugiperda larvae, as well as the consequences for their development, were investigated under laboratory conditions. Spodoptera frugiperda larvae showed obvious cannibalism after the third instar even in the presence of maize (Zea mays L., Poaceae) leaves; cannibalism was not observed in first instars. In the case of only one cannibal, the percentage of prey consumed by cannibalism decreased with higher prey density, and the predatory functional responses of fourth- to sixth-instar predators to first- to third-instar preys were fitted using the Holling II model. Compared with larvae feeding on maize only, larvae feeding on a diet of maize supplemented with third-instar conspecifics had a longer developmental duration and a higher body weight, with no significant differences in larval survival, pupation, or eclosion rates. Larvae supplied with conspecifics only, in the absence of maize leaves, generally had a lower body weight than larvae supplied with maize only, although developmental duration was still longer, and longevity and fecundity rates were lower for these larvae. Overall, consuming a small quantity of conspecifics in addition to maize leaves prolonged the developmental duration of larvae and pupae to some extent, increased the body weight, and did not impact the longevity or reproduction of S. frugiperda. However, cannibalism only, without access to maize leaves, had a detrimental effect on adult longevity and reproduction. These findings could serve as a valuable reference for studying the life history of insects that consume agricultural crops and may have potential applications for biological control.

Yellow sticky traps (YSTs) are a standard tool for insect monitoring in greenhouses. These traps have been further developed by using them in combination with green light-emitting diodes (LEDs) to increase their attractiveness towards pest insects such as aphids and whiteflies. However, also natural enemies, such as the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), are attracted to these traps. This may cause problems with biological control of the pest or may be used for indirect monitoring purposes. Therefore, we compared the attractiveness of YSTs and green (521 nm) LED traps towards E. formosa under practical growing conditions in tomato, Solanum lycopersicum L. (Solanaceae) and cucumber, Cucumis sativus L. (Cucurbitaceae), crops in the greenhouse. The aim of the study was to investigate the compatibility of LED traps with this parasitoid frequently used against the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae). The results show LED traps catching less E. formosa than standard YSTs. Moreover, LED traps also showed compatibility with other beneficial insects. The results are discussed in the context of the parasitoid's behaviour towards various green light spectra and in the context of pest and beneficial insect monitoring using different trap types. Our study will help implementing green LED traps in future insect monitoring programmes and developing new pest control strategies without affecting natural enemies.

Shifts in resource use in response to interspecific competition were thought to be necessary for the stable coexistence of consumers sharing the same resources. However, if superiority between competitors switches during development, they may achieve similar lifetime fitness without changing resource use. We tested this hypothesis by allowing two parasitoid wasp species, Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) and Trichopria drosophilae Perkins (Hymenoptera: Diapriidae), to exploit large and small Drosophila melanogaster Meigen (Diptera: Drosophilidae) pupae separately or simultaneously to examine whether they change their host preferences in response to interspecific competition. The results showed that both parasitoid species preferred large over small hosts regardless of the presence of competitors, although immature T. drosophilae generally shows a higher mortality rate than P. vindemiae when they shared the same host pupae. This could be explained by the higher fitness loss of T. drosophilae in small hosts, as body size, longevity, and fecundity of T. drosophilae offspring suffered more from a decrease in host size than P. vindemiae. In contrast, adult female T. drosophilae laid more eggs than P. vindemiae, which enabled them to outperform P. vindemiae during host exploration. Consequently, the two parasitoid species had similar numbers of offspring when they were allowed to exploit the host pupae simultaneously. This study provides insights into our understanding of how competing parasitoid species may coexist on the same resources.

Galls are thought to be induced by insects for protection, yet many gall-forming insects experience heavy parasitization. Little is known about how parasitoids locate gall-forming insects. Quadrastichus mendeli Kim & La Salle (Hymenoptera: Eulophidae) is an obligate ectoparasitoid of the larvae of Leptocybe invasa Fisher et La Salle (Hymenoptera: Eulophidae), which is an invasive gall-forming pest in eucalyptus (Eucalyptus spp., Myrtaceae) plantations. In this study, Q. mendeli and L. invasa were used to explore parasitoid behavior when locating gall-forming insects. Our results revealed that host location by Q. mendeli involved five discrete steps: walking, resting or grooming, antennating, probing and stinging. Antennation was the most frequent behavior, accounting for about half of the total time. Host location behavior of Q. mendeli occurred in the photophase. Female Q. mendeli exhibited a clear circadian rhythm: Almost all behaviors occurred during the photophase, and behavior peaked at the sixth hour of the light phase. The olfactory response rates of Q. mendeli to volatiles from galls decreased significantly after their antennae were detached. However, there was no significant difference in the host location behavior of Q. mendeli after their eyes were obscured. Our results provide essential information to explore the host location mechanisms in gall parasitoids.

Parental environments have profound consequences for offspring fitness through transgenerational transmission of resources and epigenetic factors. Locomotor activity is a functional trait of considerable ecological importance, as it determines the ability of animals to find food and mates and to disperse to more favourable environments. Although there have been studies demonstrating that animals can plastically increase their locomotor capacity in response to nutritionally stressful environments, it remains largely unexplored whether and how parental diet can adjust offspring locomotor capacity and its related traits. In this study, we tested the hypothesis that the parental intake of a nutritionally suboptimal diet would induce hyperactivity in the offspring and that this transgenerational effect could lead to improved offspring performance in an insect herbivore, the bean bug (Riptortus pedestris Fabricius) (Hemiptera: Alydidae). We compared the locomotor activity, metabolic phenotype and performance traits of two groups of R. pedestris nymphs born to parents raised on soybeans [Glycine max (L.) Merr, Fabaceae; standard diet] or peanuts (Arachis hypogaea L., Fabaceae; high-fat diet). Despite being smaller at birth, the offspring of peanut-fed parents moved faster and more frequently than those of soybean-fed parents during their early development. The newly hatched offspring born to peanut-fed parents had higher relative energy reserves in somatic tissues than those born to soybean-fed parents, indicating that differential parental provisioning could underpin this parental effect on offspring locomotor activity. Possibly through increased foraging activity, the hyperactive offspring of peanut-fed parents grew faster into heavier adults than the offspring of soybean-fed parents, implying that parentally induced increase in offspring locomotor activity is adaptive. This study provides experimental evidence for diet-mediated transgenerational plasticity of locomotor activity in invertebrates and sheds novel insights into the role of parental diet history in shaping offspring phenotype.