To understand trophic interactions and the precise ecological role of each predatory species, it is important to know which arthropod and plant resources are used by generalist predators in agroecosystems. Molecular approaches, such as the use of high‐throughput sequencing (HTS), play a key role in identifying these resources. This study develops a multiprimer metabarcoding approach for screening the most common trophic interactions of two predatory arthropods with contrasting morphologies, Rhagonycha fulva (Coleoptera: Cantharidae) and Anthocoris nemoralis (Hemiptera: Anthocoridae) collected from a peach crop. To reduce the time and cost of this metabarcoding approach, we first evaluated the effect of using two different predator‐pools of different size (10 and 23 individuals of the same species). We also used our system to analyze the performance of one and two primer pairs in the same library. Our results show that the analysis of 23 individuals together with the use of two primer pairs in the same library optimize the HTS analysis. Using these best‐performing conditions, we then analyzed the entire bodies of field‐collected predators as well as the washing solutions used to clean the insect bodies. We were able to identify both gut content (i.e., diet) and external pollen load (i.e., on the insects’ bodies). This study also demonstrates the importance of washing predatory insects’ bodies prior to HTS analysis when the target species have a considerable size (>10 mm) and hairy structures. This metabarcoding approach has significant potential for the study of trophic links in agriculture, revealing expected and unexpected trophic relationships.
Microorganisms in the guts of insects enhance the adaptability of their hosts with different lifestyles, or those that live in different habitats. Tuta absoluta is an invasive pest that is a serious threat to tomato production in China. It has quickly spread and colonized Xinjiang, Yunnan and other provinces and regions. We used Illumina HiSeq next generation sequencing of the 16S rRNA gene to study and analyze the composition and diversity of the gut microbiota of three geographical populations of T. absoluta. At the phylum level, the most common bacteria in T. absoluta across all three geographical populations were Proteobacteria and Firmicutes. An uncultured bacterium in the Enterobacteriaceae was the dominant bacterial genus in the T. absoluta gut microbiotas. There were no significant differences in alpha diversity metrics among the Spanish, Yunnan and Xinjiang populations. The structures of the gut microbiota of the three populations were similar based on PCoA and NMDS results. The results confirmed that the microbial structures of T. absoluta from different regions were similar.
Although the capacity to feed on both prey and plants is relatively widespread among pest natural enemies, mostly in predators, crop damage has rarely been reported. Little is known about the mechanisms governing crop damage occurrence by predators that can also facultatively feed on plants. This chapter aims to provide guidance on how to assess the risks of crop damage by introduced invertebrate biological control agents. Risks of crop damage do not seem to be characteristic and constant for each species but variable, depending on external factors. Based on the experience gained with the management of native facultative predators in conservation biological control, we discuss the role of variables linked to the predator, the crop plant and the target habitat when assessing risks of crop damage by introduced natural enemies. Among the variables related to the predator, capacity to consume and to injure plants and to vector plant pathogens are associated most with high risk of crop damage. When this information is not reliably available in the literature, pre-release tests must be carried out. These should include observations on plant-feeding activity and its confirmation by using chemical or immunological markers and gut content analyses. Specific trials, designed to test whether damage is caused, should take into account the variables linked to the crop that may affect its susceptibility: crop species, cultivar, growth stage and tissue. Risks posed by plant-feeding predators should be analysed in relation to the potential benefits expected from such predators for biological control.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.