De novo transcriptome assemblies of Epicauta tibialis provide insights into the sexual dimorphism in the production of cantharidin

The Detoxification Enzymatic Responses of Plutella xylostella (Lepidoptera: Plutellidae) to Cantharidin

Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most destructive pests of Brassicaceae vegetables. Cantharidin is an insect-derived defensive toxin, which has been reported to have toxicity to a variety of pests and especially lepidopteran pests. Although the toxicity of cantharidin on P. xylostella has been demonstrated, there is little information available on the specific detoxification response of P. xylostella against cantharidin. This study investigates the enzymatic response (including serine/threonine phosphatases [PSPs], carboxylesterases [CarEs], glutathione-S-transferases [GSTs], and cytochrome P450 monooxygenases [P450]) in P. xylostella to the sublethal and low lethal concentrations of cantharidin (LC10 and LC25). Results showed that the inhibitory activity of PSPs was increased and then decreased in vivo, while PSPs activity could be almost completely inhibited in vitro. Interestingly, the activities of detoxification enzymes (GST, CarE, and P450) in P. xylostella displayed a trend of decreasing and then increasing after exposure to the two concentrations of cantharidin. Notably, the increase in P450 enzyme activity was the most significant. The increasing trend of detoxification enzyme activity was congruent with the recovery trend of PSPs activity. This study contributes to our understanding of the detoxification mechanism of cantharidin in P. xylostella and helps in the further development of biogenic agents.

The complete mitochondrial genome of Meloeproscarabaeus (Coleoptera, Meloidae): genome descriptions and phylogenetic inferences

Oil beetles are meloids, which are characterised for their cleptoparasitic habits in bee nests and oily fluid of cantharidin that causes blistering and swelling of the skin. The complete mitochondrial genome of Meloeproscarabaeus is determined using the next-generation sequencing technology and its genomic characteristics are described. The 15,653-bp long genome is a circular molecule consisting of 13 protein-coding genes (PCG), 22 transport RNA, two ribosomal RNA, and a control region. The A + T bias of the mitochondrial genome is manifested in the complete sequence and the codon usage of protein-coding genes. The genetic distance within and between genera is calculated to confirm the taxonomic status of M.proscarabaeus. The phylogenetic relationships among 15 available meloid taxa are inferred by the maximum likelihood (ML) method based on 13 mitochondrial PCGs. The ML trees resulting from nucleotide and amino acid datasets recover both the monophyly of Meloe and Epicauta and the polyphyly comprising Hycleus and Mylabris. This study provides the first description of a mitochondrial genome belonging to the genus Meloe. The mitochondrial genome sequence and its characteristics are expected to be conducive to future studies on taxonomy, systematics, and molecular phylogenetics of the family Meloidae.