Managing Super Pests: Interplay between Pathogens and Symbionts Informs Biocontrol of Whiteflies.

Bemisia tabaci is distributed globally and incurs considerable economic and ecological costs as an agricultural pest and viral vector. The entomopathogenic fungus Metarhizium anisopliae has been known for its insecticidal activity, but its impacts on whiteflies are understudied. We investigated how infection with the semi-persistently transmitted Cucurbit chlorotic yellows virus (CCYV) affects whitefly susceptibility to M. anisopliae exposure. We discovered that viruliferous whiteflies exhibited increased mortality when fungus infection was present compared to non-viruliferous insects. High throughput 16S rRNA sequencing also revealed significant alterations of the whitefly bacterial microbiome diversity and structure due to both CCYV and fungal presence. Specifically, the obligate symbiont Portiera decreased in relative abundance in viruliferous whiteflies exposed to M. anisopliae. Facultative Hamiltonella and Rickettsia symbionts exhibited variability across groups but dominated in fungus-treated non-viruliferous whiteflies. Our results illuminate triangular interplay between pest insects, their pathogens, and symbionts-dynamics which can inform integrated management strategies leveraging biopesticides This work underscores the promise of M. anisopliae for sustainable whitefly control while laying the groundwork for elucidating mechanisms behind microbe-mediated shifts in vector competence.

Discovery of novel whitefly vector proteins that interact with a virus capsid component mediating virion retention and transmission.

Specificity and efficiency of plant virus transmission depend largely on protein-protein interactions of vectors and viruses. Cucurbit chlorotic yellows virus (CCYV), transmitted specifically by tobacco whitefly, Bemisia tabaci, in a semi-persistent manner, has caused serious damage on cucurbit and vegetable crops around the world. However, the molecular mechanism of interaction during CCYV retention and transmission are still lacking. CCYV was proven to bind particularly to the whitefly foregut, and here, we confirmed that the minor coat protein (CPm) of CCYV is participated in the interaction with the vector. In order to identify proteins of B. tabaci that interact directly with CPm of CCYV, the immunoprecipitation (IP) assay and DUALmembrane cDNA library screening technology were applied. The cytochrome c oxidase subunit 5A (COX), tubulin beta chain (TUB) and keratin, type I cytoskeletal 9-like (KRT) of B. tabaci shown strong interactions with CPm and are closely associated with the retention within the vector and transmission of CCYV. These findings on whitefly protein-CCYV CPm interactions are crucial for a much better understanding the mechanism of semi-persistent plant virus transmission by insect vectors, as well as for implement new strategies for effective management of plant viruses and their vector insects.

The Mitogenome of Aleuroclava Psidii (Singh, 1931) (Hemiptera: Aleyrodidae) and Increased Number of Mitochondrial Gene Rearrangements in Whiteflies.

BACKGROUND: In this study, the entire mitochondrial genome (mitogenome) of Aleuroclava psidii (Singh, 1931) (Hemiptera: Aleyrodidae) was sequenced. The species A. psidii is currently classified in the subfamily Aleyrodinae. This mitogenome is the first representative from the genus Aleuroclava. METHODS: Next-generation sequencing was used to obtain the molecular data. We conducted phylogenetic analyses with 18 existing mitogenomes of whiteflies and three outgroups of psyllids, under the Maximum likelihood and Bayesian inference criteria. RESULTS: The arrangement of genes differed between the mitogenome of A. psidii and the putative ancestral insect mitogenome, and also differed from the mitogenomes of other whiteflies. Mitochondrial gene rearrangements involved the transpositions of trnQ, trnY, and the protein-coding gene nad1. Most hemipteran mitogenomes have the same mitochondrial gene order as that inferred to be ancestral for insects. However, there are an increased number of gene rearrangements in the mitogenomes of whiteflies. Phylogenetic reconstructions supported Aleurodicinae and Aleyrodinae as being monophyletic. CONCLUSIONS: Comparison of the gene order of mitogenomes revealed a clade-specific evolutionary trend in whiteflies. This study demonstrates the potential of using structural rearrangements to resolve major phylogenetic relationships within Aleyrodidae.

A Semipersistent Plant Virus Differentially Manipulates Feeding Behaviors of Different Sexes and Biotypes of Its Whitefly Vector.

It is known that plant viruses can change the performance of their vectors. However, there have been no reports on whether or how a semipersistent plant virus manipulates the feeding behaviors of its whitefly vectors. Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is an emergent plant virus in many Asian countries and is transmitted specifically by B and Q biotypes of tobacco whitefly, Bemisia tabaci (Gennadius), in a semipersistent manner. In the present study, we used electrical penetration graph (EPG) technique to investigate the effect of CCYV on the feeding behaviors of B. tabaci. The results showed that CCYV altered feeding behaviors of both biotypes and sexes of B. tabaci with different degrees. CCYV had stronger effects on feeding behaviors of Q biotype than those of B biotype, by increasing duration of phloem salivation and sap ingestion, and could differentially manipulate feeding behaviors of males and females in both biotype whiteflies, with more phloem ingestion in Q biotype males and more non-phloem probing in B biotype males than their respective females. With regard to feeding behaviors related to virus transmission, these results indicated that, when carrying CCYV, B. tabaci Q biotype plays more roles than B biotype, and males make greater contribution than females.

RNA interference of the P450 CYP6CM1 gene has different efficacy in B and Q biotypes of Bemisia tabaci.

BACKGROUND: Cytochrome P450 monooxygenases have been proven to be associated with high resistance in Bemisia tabaci B biotype (Middle East-Asia Minor 1 genetic group) and Q biotype (Mediterranean genetic group) to the neonicotinoid class of insecticides. In this study, the RNA interference (RNAi) effects on P450 CYP6CM1 gene expression, mortality and pesticide-detoxifying ability between B. tabaci B and Q biotypes were compared in an attempt to provide a basis for potential RNAi application in management of this pest. RESULTS: Double-stranded RNAs (dsRNAs) of P450 CYP6CM1 genes corresponding to the B and Q biotypes were synthesised using specific primers and introduced into the insect body of B. tabaci adults through membrane feeding. The results showed that dsRNAs significantly silenced the target genes in B. tabaci with dsRNA concentration or treatment time, and silencing was more effective in B biotype than in Q biotype. Feeding dsRNAs led to high mortality in both biotypes, with higher mortality in B biotype (up to 85.88%) than in Q biotype (up to 56.40%). In addition, ability to detoxify imidacloprid and nicotine was inhibited in dsRNA-treated adults of both biotypes, more efficiently in B biotype than in Q biotype. CONCLUSION: RNA interference of the P450 CYP6CM1 gene reduced gene expression, increased mortality, and inhibited the ability to detoxify a pesticide or a plant secondary metabolite in both biotypes of B. tabaci, with better efficacy in B biotype than in Q biotype.