Evolutionary timescale of chalcidoid wasps inferred from over one hundred mitochondrial genomes.

Chalcidoidea is one of the most biologically diverse groups among Hymenoptera. Members are characterized by extraordinary parasitic lifestyles and extensive host ranges, among which several species attack plants or serve as pollinators. However, higher-level chalcidoid relationships remain controversial. Here, we performed mitochondrial phylogenomic analyses for major clades (18 out of 25 families) of Chalcidoidea based on 139 mitochondrial genomes. The compositional heterogeneity and conflicting backbone relationships in Chalcidoidea were assessed using various datasets and tree inferences. Our phylogenetic results supported the monophyly of 16 families and polyphyly of Aphelinidae and Pteromalidae. Our preferred topology recovered the relationship (Mymaridae+(Signiphoridae+Leucospidae)+(Chalcididae+((Perilampidae+Eucharitidae)+ remaining Chalcidoidea)))). The monophyly of Agaonidae and Sycophaginae was rejected, while the gall-associated ((Megastigmidae+Ormyridae)+(Ormocerinae+Eurytomidae)) relationship was supported in most results. A six-gene inversion may be a synapomorphy for most families, whereas other derived gene orders may introduce confusion in phylogenetic signals at deeper nodes. Dating estimates suggested that Chalcidoidea arose near the Jurassic/Cretaceous boundary and that two dynamic shifts in diversification occurred during the evolution of Chalcidoidea. We hypothesized that the potential codiversification between chalcidoids and their hosts may be crucial for accelerating the diversification of Chalcidoidea. Ancestral state reconstruction analyses supported the hypothesis that gall-inducers were mainly derived from parasitoids of gall-inducers, while other gall-inducers were derived from phytophagous groups. Taken together, these findings advance our understanding of mitochondrial genome evolution in the major interfamilial phylogeny of Chalcidoidea.

Proteomic Analyses of Whitefly-Begomovirus Interactions Reveal the Inhibitory Role of Tumorous Imaginal Discs in Viral Retention.

In nature, plant viruses are mostly transmitted by hemipteran insects, such as aphids, leafhoppers, and whiteflies. However, the molecular mechanisms underlying the interactions between virus and insect vector are poorly known. Here, we investigate the proteomic interactions between tomato yellow leaf curl virus (TYLCV, genus Begomovirus, family Geminiviridae), a plant virus, and its vector whitefly (Bemisia tabaci) species complex. First, using a yeast two-hybrid system, we identified 15 candidate whitefly proteins interacting with the coat protein of TYLCV. GO and KEGG pathway analysis implicated that these 15 whitefly proteins are of different biological functions/processes mainly including metabolic process, cell motility, signal transduction, and response to stimulus. We then found that the whitefly protein tumorous imaginal discs (Tid), one of the 15 whitefly proteins identified, had a stable interaction with TYLCV CP in vitro, and the DnaJ_C domain of Tid301-499aa may be the viral binding site. During viral retention, the expression of whitefly protein Tid was observed to increase at the protein level, and feeding whiteflies with dsRNA or antibody against Tid resulted in a higher quantity of TYLCV in the whitefly body, suggesting the role of Tid in antiviral infection. Our data indicate that the induction of Tid following viral acquisition is likely a whitefly immune response to TYLCV infection.