Entomologia Experimentalis et Applicata最新文献

Delia platura (Meigen) (Diptera: Anthomyiidae) is a generalist dipteran pest that attacks germinating seeds of cucurbits, crucifers, legumes, and among others. Delia platura can cause economically important damage in early spring that leads to stand losses in temperate regions. Thus, researching the biology and behavior of this pest and running bioassays with different life stages is essential to developing effective management strategies. Maintaining D. platura colonies allows for laboratory and field experiments to occur outside of the growing season. However, current rearing protocols yield high mortality rates at the egg stage and have been difficult to replicate. Here, we present an updated protocol for reduced offspring mortality, improved colony health, and greater ease of maintenance.

The nutritional regimens of wasp parasitoids can influence the body size of their progeny and their parasitization capacity. This study aimed to evaluate the impact of food resources (glucose, honey, and no food control) on the body size of offspring and the parasitization capacity of Paracentrobia subflava (Girault) (Hymenoptera: Trichogrammatidae), an egg parasitoid of the corn leafhopper pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae). Female P. subflava were exposed to D. maidis eggs for 72 h under three feeding treatments: glucose, honey, and no food control. The body size of the emerged offspring was measured, and parasitization capacity was evaluated by assessing the abundance, rate of parasitism, and emergence rate of P. subflava. The results showed that female offspring from mothers fed with glucose or honey had significantly larger head sizes than offspring from unfed mothers. Male offspring from fed mothers exhibited longer forewings than those from unfed mothers. However, no significant differences were observed in the total abundance of egg parasitoids, parasitism rates, or emergence rates across the feeding treatments. These findings suggest that sugar-based diets affect the size and shape of offspring body structures in P. subflava but do not impact their parasitization capacity, highlighting the proovigenic nature of this species.

A significant emphasis of insect symbiont research has focused on the digestive tract and elucidating whether bacteria colonize and proliferate or transiently pass through is integral to our understanding of microbial community structure and host–microbe interactions. The larval stages of the greater wax moth, Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae), have become increasingly used in studies that are heavily influenced by host–microbiome dynamics (e.g., plastic biodegradation and innate immunity). However, it is presently unclear whether continual bacterial recruitment is required to sustain the bacterial assemblages, and the extent by which gut bacterial flora is a reflection of their food substrate. Therefore, the objective of this study was to discern between transient and more persistent gut microbes harbored by G. mellonella larvae, and to evaluate their relative contributions to microbial diversity and abundance. We used 16S rRNA sequencing to characterize and compare the bacteriomes of G. mellonella to their natural honeycomb diet throughout larval development, as well as to caterpillars subjected to a 4-day starvation period. Then, we used qPCR to measure relative bacterial abundances at each instar. Our results indicate larval gut bacterial composition and abundance are predominantly diet-driven, with a myriad of bacterial genera seemingly transiently present. However, several genera (e.g., Ralstonia, Pelomonas, and Cutibacterium) appear to be more permanent fixtures, presumably colonizing and proliferating in the digestive tract. Moreover, some bacterial genera co-occur, forming non-random associations that may be indicative of functional synergies. Overall, this study advances our knowledge of lepidopteran gut microbial dynamics and provides valuable information for an emerging invertebrate model.

The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), represents a major threat to tomato crops worldwide. The ectoparasitoid Goniozus legneri Gordh (Hymenoptera: Bethylidae) parasitizes T. absoluta larvae, while inherited sterility (IS) is an environmentally friendly option for controlling lepidopteran pests. This study aimed to elucidate the life history traits of G. legneri when parasitizing and feeding on T. absoluta larvae from untreated parents versus broods of irradiated parental males, exploring the potential integration of this parasitoid and IS for T. absoluta control. Overall, there were no significant differences in biological traits between treatments, except for the number of larvae killed per female and female longevity, both of which were higher in females feeding on larvae descended from irradiated parental males. Developmental time and survival of preimaginal stages showed no significant differences between the origins of T. absoluta larvae studied. Compared with other hosts of G. legneri, the parasitoid produced fewer offspring and showed suboptimal biological parameters when developed on T. absoluta. In conclusion, relying solely on G. legneri for T. absoluta control, either independently or in conjunction with IS, is not recommended. Nonetheless, exploring its combination with other techniques, such as the use of pheromone traps or biorational insecticides, merits further investigation.

Global warming is predicted to increase mean temperature affecting species interactions, including those among co-existing aphids in crop fields. These interactions can influence aphid community dynamics and their impacts on crops. Most previous studies concerning the warming effects on aphids have focussed on a single species or tested the thermal responses of different species separately, overlooking how interspecific interactions might alter the relative dominance of aphid communities under warming conditions. Consequently, the impact of modified species interactions on aphid communities in warming climates remains unclear. To investigate this, we conducted an experiment with five mean temperature levels using four cereal aphid species [Metopolophium dirhodum (Walker), Rhopalosiphum padi (Linnaeus), Sitobion avenae (Fabricius) and Schizaphis graminum (Rondani)] (all Hemiptera: Aphididae) under both conditions of with and without species interactions. Our results showed that changes in mean temperature and species interactions significantly altered the relative dominance of aphid communities. Specifically, the presence of species interactions facilitated population growth of two species (R. padi and S. graminum), whereas it depressed that of the other two (M. dirhodum and S. avenae). Importantly, the relative dominance of these species changed as temperature increased. Our study thus emphasizes that both climate warming and species interactions might be key drivers shifting the relative dominance and community structure of co-existing aphid pests, and more broadly, of many other co-occurring species in natural and agricultural ecosystems.

Black soldier fly (BSF), Hermetia illucens (L.) (Diptera: Stratiomyidae), larvae are widely used as bioconverters of agrifood by-products into valuable proteins for animal feed. In adults, females and males have complex reproductive tracts, suggesting a strong pressure on sperm management. Such complexity in reproductive tracts is typically shaped by post-copulatory sexual selection (PCSS). Whereas multiple mating—the foundation of PCSS hypotheses—has been observed in BSF, its underlying phenotypic determinants and implications for sperm storage and use remain unknown. In this study, matings were tested during three consecutive days under laboratory conditions. Spermatozoa were counted in the reproductive tracts of males and females after consecutive matings. The results show that sperm amount in males was not correlated with their size. Mating occurred in 54% of males and 58% of females and was not influenced by size in either males or females; among them, multiple mating was observed in 19% of females and 50% of males. Sperm counts in males and females did not decrease with males' successive matings. Females were observed to store less spermatozoa when they copulated longer. The number and fertility of eggs did not change with female rank. This showed that male sperm production is enough to ensure egg fertilization even after successive matings. In conclusion, based on the obtained results, sperm quantity is not an issue in BSF, and mating strategy must be investigated in other traits, such as sperm quality, paternity biases or other ejaculate components.

Gut bacterial composition is closely associated with the food intake and developmental age of herbivorous insects. In this study, we aimed to investigate the diversity of larval gut bacteria in different instar stages of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) feeding on different hosts. Gut bacterial DNA was extracted from the 1st, 2nd, 3rd, and 4th instar larvae of T. absoluta feeding on tomatoes, potatoes, and wolfberries for three generations. Subsequently, diversity and richness of gut bacteria were analyzed via the second-generation Illumina MiSeq high-throughput sequencing. Alpha diversity index analysis revealed the highest diversity and abundance of gut bacteria in the T. absoluta larvae fed wolfberry and potato leaves, respectively. The highest gut bacterial diversity and richness were observed in the 1st-instar larvae feeding on potato and tomato leaves. Tuta absoluta feeding on wolfberry leaves exhibited the lowest gut bacterial diversity in the 1st-instar stage and highest abundance in the 2nd-instar stage. Proteobacteria was the dominant phylum in the gut bacteria of stages 1–4 instar larvae feeding on different host plants. The dominant genus was Enterobacter (60.1%) in the 4th-instar T. absoluta larvae feeding on tomatoes and Wolbachia in those feeding on other plants. PICRUSt2 gene function prediction revealed that the larval gut bacteria of T. absoluta played essential roles in food digestion and nutrient supply. Specifically, Wolbachia may enhance nucleotide metabolism in T. absoluta feeding on potatoes. Overall, this study provides a basis to explore the interactions of T. absoluta with gut bacteria and suggests directions for its adaptive evolution and integrated management.

The 18th Symposium on Insect-Plant Relationships (SIP-18) took place in Bielefeld, Germany, in August 2024. Since the previous meeting (SIP-17) could be executed only online because of the pandemic, we enjoyed meeting in person even more. The conference has resulted in five exciting contributions to the journal Entomologia Experimentalis et Applicata. Two of these are reviews, one presenting an overview of the arthropod fauna associated with the plant genus Annona and the other providing an ecological and evolutionary perspective on pharmacophagy—that is, the attraction of insects to plant specialized metabolites and their use for purposes other than nutrition in insects. Three research articles show original work on differential gene expression in larvae sequestering plant metabolites, resistance to thrips in several Chrysanthemum accessions, and the role of light intensity in physical defense against native and invasive caterpillar species in trees, respectively. These articles are presented in this themed issue as the proceedings of SIP-18, in addition to nine other articles relevant to the research field of insect–plant relationships.

Annona L. species, custard apples, interact with a wide range of arthropods, including both herbivorous arthropods and pollinators that play vital roles in their ecology. Understanding their interactions with phytophagous arthropods and pollinators is crucial for developing effective pest and crop management strategies. Annona species present diverse secondary metabolites of significant interest for their potential defensive roles against arthropod pests. In addition, the introduction of Annona crops to new regions using planting material carries risks, including the potential introduction of pests that may harm local ecosystems and crops. Nonetheless, the diversity of Annona's associated phytophagous arthropods remains largely underexplored. This study aimed to fill this gap by documenting the diversity of arthropods associated with Annona species across various geographical regions using information available in the scientific literature and specialized databases. We explored whether the phylogenetic relationships of Annona species are also reflected in their associated phytophagous arthropods. Our review identified 614 arthropod species, with most associations recorded on the cultivated species A. muricata L., A. squamosa L., and A. cherimola Mill. (Annonaceae). The most common orders were Hemiptera, followed by Lepidoptera and Coleoptera. The study also revealed that arthropod assemblages associated with genetically closely related Annona species tend to be more similar to those of more distantly related species. These findings illustrate the diverse arthropod communities associated with these fruit trees, offering valuable insights into plant–insect interactions and contributing to the prevention of phytosanitary risks in their cultivation.

Despite advancements in barcoding and metabarcoding, preserving high-quality DNA from field-collected arthropods remains challenging. Although various fixatives and preservatives are used for DNA recovery in Coleoptera (Carabidae) and Lepidoptera (Noctuidae, Nolidae, Geometridae, and Tortricidae), their effects on DNA quality across trapping methods are not fully understood. This study evaluates fixation and preservation strategies affecting DNA integrity, focusing on pH changes before and after tissue grinding to improve consistency. For Carabidae, Calathus fuscipes (L.) were collected with a Malaise trap, while Platynus assimilis (Paykull) were collected via emergence traps and pitfall traps (with and without roof), using propylene glycol as a fixative. Preservation methods included storage in propylene glycol, 96% ethanol, or drying, with samples kept at −20°C for 1 year. Propylene glycol samples were washed with distilled water prior to grinding. Additional fixatives in individual trapping included ethylene glycol, propylene glycol, ethanol, brine, ethyl acetate, vinegar, and drying (with and without silica gel), stored at −20°C for 3 months. For Lepidoptera, specimens were categorized by size: large—Agrostis exclamationis (L.) (Noctuidae), medium—Meganola strigula (Denis et Schiffermüller) (Nolidae), Eupithecia insigniata (Hübner) (Geometridae), and small—Pelochrista caecimaculana (Hübner) (Tortricidae). Specimens were treated with chloroform (vapor and soaked) or cyanide vapors and stored at room temperature for 3 months. DNA quality was assessed through fragmentation analysis and PCR amplification of COI fragments (658, 313, and 157 bp for Coleoptera and 658, 311, and 220 bp for Lepidoptera) with Sanger sequencing. Results showed reduced DNA integrity in diluted Malaise trap samples, while distilled water washing improved readability in emergence trap samples. Brine proved a cost-effective preservative. For Lepidoptera, DNA preservation depended on sample size and fixative, with small chloroform-soaked specimens yielding non-sequencable DNA, while vapor-treated samples remained sequencable. This study offers insights to optimize DNA yield and preservation for arthropod research.