Manipulation of Microbial Symbionts in Bemisia tabaci and Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) Reveals Divergent Impacts on Insect Host Fitness and Plant Defense Modulation

Insect–microbe symbioses play pivotal roles in host ecology and plant–insect interactions, yet their species-specific functions in agricultural pests remain less understood. This study elucidates the functional role of symbiotic microbial communities in mediating insect host fitness and plant defense responses in two economically important whitefly species, Bemisia tabaci Gennadius and Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae). Using integrated molecular and physiological approaches, we characterized species-specific responses to antibiotic treatments (rifampicin and tetracycline) and their cascading effects on tripartite plant–insect–microbe interactions. In B. tabaci, antibiotic exposure induced significant depletion of the obligate symbiont Portiera and facultative Rickettsia (except for tetracycline-mediated Portiera proliferation), correlating with enhanced plant immune responses. In parallel, antibiotic treatments increased the titers of Hamiltonella and Rickettsia alongside constitutive plant defense suppression in T. vaporariorum, though tetracycline uniquely induced AOS expression elevation. Developmental assays revealed stage-specific vulnerabilities, with late nymphal and pupal stages showing high sensitivity to symbiont disruption, culminating in complete mortality within 40–50 d post-treatment. These findings show that microbial symbionts are essential to whitefly nutrition and evasion of plant anti-herbivore defenses. Our results provide a mechanistic basis for understanding symbiont-assisted invasion success in these whitefly species and underscore the potential of microbiome-targeted approaches for sustainable whitefly management.