Data Sheet 1_Influence of weather and seasonal factors on whitefly dynamics, associated endosymbiotic microbiomes, and Begomovirus transmission causing tomato leaf curl disease: insights from a metagenomic perspective.pdf

IntroductionBemisia tabaci (Gennadius) is a globally significant agricultural pest, responsible for transmitting over 120 plant viruses, including those from the Begomovirus genus, which contribute to considerable crop losses. The species complex comprises cryptic species, associated with a diverse array of bacterial endosymbionts that play essential roles in host nutrition, virus transmission, and overall host adaptability. These endosymbionts are classified into primary and secondary categories, with primary endosymbionts forming obligatory, long-term associations, and secondary endosymbionts influencing factors such as biotype differentiation and vector competency. Notably, these microbial communities enhance B. tabaci’s capacity to transmit viruses, including the tomato leaf curl virus (ToLCuV), which poses a significant threat to tomato production.
MethodsIn this study, we examined the population dynamics of B. tabaci across three major tomato-growing regions in Karnataka, South India, focusing on their seasonal associations with endosymbionts and the incidence of tomato leaf curl disease (ToLCuD). Multiple regression analysis was employed to assess the influence of weather parameters on whitefly populations and disease prevalence. Additionally, we constructed a metagenomic profile to evaluate the effects of geographical location, seasonality, environmental factors, and agricultural practices on the bacterial communities associated with B. tabaci. Species-specific primers were used to validate the presence and diversity of these bacterial communities.
ResultsMeteorological data revealed a positive correlation between temperature and B. tabaci populations, which corresponded with an increased incidence of ToLCuD. Genetic characterization of the whitefly identified Asia II-5 and Asia II-7 cryptic species as the dominant forms in the surveyed regions, with Portiera emerging as the most prevalent endosymbiont. A more in-depth analysis of the microbial communities associated with B. tabaci, utilizing 16S rRNA metagenomic sequencing, revealed a dominance of the Proteobacteria phylum. The endosymbiotic bacterial consortium was primarily composed of Candidatus Portiera, Candidatus Hamiltonella, Candidatus Rickettsia, and Candidatus Arsenophonus.
DiscussionThe metagenomic analysis revealed a highly diverse array of bacterial communities, with 92% of sequences classified under Proteobacteria, representing a spectrum of microbial types associated with B. tabaci ranging from parasitic and pathogenic to mutualistic. Within this phylum, Alphaproteobacteria were predominant, known for their role as facultative symbionts, while Gammaproteobacteria provided essential nutrients to arthropods, enhancing their survival and fitness. The interplay of continuous and intensive tomato cultivation, elevated temperatures, favorable host plants, and abundant viral inoculum creates an ideal environment for the proliferation of B. tabaci and the widespread transmission of ToLCuD. The presence of diverse cryptic species of B. tabaci, which are efficient viral vectors, further complicates the situation. These findings underscore the urgent need for integrated management strategies globally to control both whitefly populations and ToLCuD, ensuring the protection of tomato crops and the sustainability of farmer livelihoods.

引言
烟粉虱（Bemisia tabaci (Gennadius)）是全球极具影响力的农业害虫，可传播包括双生病毒属（Begomovirus）在内的120余种植物病毒，造成巨额作物损失。该物种复合体内包含多种隐存种，其与多样的细菌内共生体紧密关联，这些内共生体在宿主营养供给、病毒传播及宿主整体适应性调控中发挥关键作用。内共生体可分为初级与次级两类：初级内共生体与宿主形成专性长期共生关系；次级内共生体则影响生物型分化、传毒能力等重要性状。值得注意的是，这类微生物群落可显著增强烟粉虱的病毒传播能力，其中番茄曲叶病毒（tomato leaf curl virus, ToLCuV）对番茄生产构成严重威胁。

材料与方法
本研究针对印度南部卡纳塔克邦的三大番茄主产区，调查了烟粉虱的种群动态，重点分析其与内共生体的季节关联以及番茄曲叶病（tomato leaf curl disease, ToLCuD）的发生情况。采用多元回归分析评估气象参数对烟粉虱种群及病害流行的影响。此外，通过构建宏基因组图谱，探究地理区位、季节节律、环境因子及农业生产方式对烟粉虱相关细菌群落的影响；并使用物种特异性引物验证这些细菌群落的存在与多样性。

结果
气象数据显示，温度与烟粉虱种群数量呈正相关，这与番茄曲叶病发病率升高相吻合。对烟粉虱的遗传鉴定表明，亚洲II-5和亚洲II-7隐存种为调查区域的优势类群，而波氏菌属（Portiera）是最普遍的内共生体。进一步利用16S rRNA宏基因组测序对烟粉虱相关微生物群落进行深度分析，结果显示变形菌门（Proteobacteria）为优势菌群。该内共生细菌群落主要由候选波氏菌属（Candidatus Portiera）、候选汉密尔顿菌属（Candidatus Hamiltonella）、候选立克次体属（Candidatus Rickettsia）和候选阿申丰氏菌属（Candidatus Arsenophonus）构成。

讨论
宏基因组分析揭示了高度多样的细菌群落，其中92%的序列隶属于变形菌门，涵盖了与烟粉虱相关的各类微生物类群，从寄生性、致病性到互利共生性均有涉及。该门内以α-变形菌纲（Alphaproteobacteria）为主，这类细菌常作为兼性共生体发挥作用；而γ-变形菌纲（Gammaproteobacteria）则可为节肢动物提供必需营养，提升其生存与适合度。持续集约的番茄种植模式、高温环境、适宜的宿主植物及充足的病毒接种源，共同构建了烟粉虱大量繁殖与番茄曲叶病广泛传播的理想环境。此外，多种高效传毒的烟粉虱隐存种的存在进一步加剧了这一问题。本研究结果凸显了全球范围内制定综合治理策略的迫切性，以同时防控烟粉虱种群与番茄曲叶病，保障番茄作物安全与农户生计的可持续性。