extracting-venom-from-parasitoid-wasp-trichogramma-dendrolimi-using

Extracting Venom from the Parasitoid Wasp <em>Trichogramma dendrolimi</em> Using an Artificial Host

Parasitoid wasps are a diverse group of hymenopteran insects that serve as invaluable resources for pest biocontrol. To ensure successful parasitism, ...

Nanjing Agricultural University

Ministry of Agriculture

Sanya Institute of Nanjing Agricultural University

Insects perceive dangerous or attractive chemicals in the environment (such as the presence of predators, food or mates) through their olfaction and gustation. This leads to host searching, mate finding and other behaviors that are critical for insect survival. These vital activities are mediated by many chemosensory receptor proteins, including odorant receptors (ORs), gustatory receptors (GRs) and ionotropic receptors (IRs). Trichogramma japonicum Ashmead (Hymenoptera: Trichogrammatidae) is a commonly used egg parasitoid for controlling lepidopteran pests in rice fields. To reveal the roles of its olfactory and gustatory systems in biological control, we systematically analyzed major chemosensory receptor genes from T. japonicum. Through transcriptomic analyses of male and female heads, we found that the differentially expressed genes (DEGs) were mainly related to chemosensory functions, and there were more chemosensory-related genes expressed in female heads than male heads, which may be related to the need for females to search for their hosts or sense male pheromone. Furthermore, we identified 66 chemosensory receptor genes, including 51 ORs, seven IRs and eight GRs, that were most closely relate to those of other hymenopteran species according to the results of both Blast best-hit and phylogenetic analyses. The tissue expression profile showed that 65 of the 66 chemosensory receptors were highly expressed in the heads, suggesting their putative roles in olfaction and gustation. In addition, the sex-specific expression patterns suggested their potential functions in host-seeking or mate sensing behaviors. This study may provide base for further understanding the olfactory and gustatory systems of T. japonicum and increasing its efficiency in pest control in the future.

Transcriptomic analyses of chemosensory genes in Trichogramma japonicum (Hymenoptera: Trichogrammatidae).

The two-spotted spider mite, Tetranychus urticae, is a major agricultural pest with a cosmopolitan distribution, and its polyphagous habits provide a model for investigating herbivore-plant interactions. There are two body color forms of T. urticae with a different host preference. Comparative genomics and transcriptomics are used here to investigate differences in responses of the forms to host plants at the molecular level. Biological responses of the two forms sourced from multiple populations are also presented.

Comparative genome and transcriptome analyses reveal innate differences in response to host plants by two color forms of the two-spotted spider mite Tetranychus urticae.

Despite its substantial costs, sexual reproduction dominates in animals. One popular explanation for the paradox of sex is that asexual reproduction is more likely to accumulate deleterious mutations than sexual reproduction. To test this hypothesis, we compared the mitogenomes of two asexual wasp strains,  and  to their sexual relatives. These two asexual strains represent two different transition mechanisms in  from sexual to asexual reproduction. Asexual  is induced by , while  presumably originated from interspecific hybridization. We sequenced and assembled complete mitochondrial genomes of asexual  and . Compared to four sexual relatives, we found no evidence of higher mutation accumulation in asexual  mitogenomes than in their sexual relatives. We also did not detect any relaxed selection in asexual  mitogenomes. In contrast, the intensified selection was detected in Nad1 and Nad4 of the asexual  mitogenome, suggesting more purifying selection. In summary, no higher mitochondrial mutation accumulation was detected in these two asexual  strains. This study provides a basis for further investigating mitochondrial evolution and asexual reproduction in .

Mitochondrial Genomes of Two Asexual  (Hymenoptera: Trichogrammatidae) Strains and Comparison with Their Sexual Relatives.

Parasitoid wasps are invaluable agents in pest biological control. Early detection and identification of parasitoid immatures are vital in characterizing parasitoid-host interactions and for evaluating parasitism rates accurately in the field. Trichogramma is the most widely used parasitoid wasp, and several studies have been performed for its molecular identification. However, those studies were mainly focused on Trichogramma adults and rarely on immatures. Here, we report a method to detect and identify Trichogramma larvae in their host eggs. We designed a pair of Trichogramma-specific primers that amplified Trichogramma mtCOI sequences from Corcyra cephalonica (Stainton) eggs parasitized by any of eight Trichogramma species tested but not from nonparasitized eggs of four lepidopteran hosts. This PCR method reliably detected Trichogramma immatures in parasitized eggs as early as 1 h after parasitism. We further developed an RFLP (restriction fragment length polymorphism) assay using restriction enzymes SspI and VspI to differentiate eight Trichogramma species at their immature stage. Overall, we developed a sensitive and reliable PCR-RFLP method to detect and identify immature-stage Trichogramma in their lepidopteran hosts. This method shows promise for conveniently identifying Trichogramma in insectaries and accurately evaluating parasitism rates in the field.

Early Detection and Identification of Parasitoid Wasps Trichogramma Westwood (Hymenoptera: Trichogrammatidae) in Their Host Eggs Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism.

Zhi-chao Yan

Department of Entomology

Nanjing Agricultural University

Extracting Venom from the Parasitoid Wasp Trichogramma dendrolimi Using an Artificial Host