Correlation-Based Network Analysis of the Influence of Bemisia tabaci Feeding on Photosynthesis and Foliar Sugar and Starch Composition in Soybean

SIMPLE SUMMARY: Bemisia tabaci affects plant performance by feeding directly from its energy sources, making it difficult to quantify crop damage, which is indirectly assessed through losses in productivity. The goal of this study was to characterize the influence of B. tabaci feeding on soybean, an economically valuable crop, and attempt to identify the optimal parameter for direct quantification of crop damage. A correlation network was created to extract biological interactions between the plant and B. tabaci nymphs at different densities and plant stages. Nymphs were more abundant during the vegetative stage, and a strong correlation between the density of nymphs and starch and fructose content was observed. The photosynthetic parameter turn-over number N was positively correlated with nymph density at a low-infestation level and negatively correlated with nymphs when they occur at a high infestation level. This association between nymph density and N may allow for development of a ranking scale to predict pest density, representing a useful tool for evaluating the potential impact of B. tabaci on soybean, especially in large areas, where nymph monitoring can be time-consuming. ABSTRACT: Bemisia tabaci (MEAM1) represents a species of economic importance in soybean. One of the obstacles to the management of B. tabaci is the quantification of damage by the pest because damage is indirectly inferred through losses in productivity. The objective of this study was to characterize the influence of B. tabaci feeding on soybean by assessing effects on photosynthetic parameters and the sugar and starch content of soybean leaves. The goal was to identify the optimal parameter to directly quantify pest damage on crop yield. Correlation networks were created among data on sugar content (fructose, glucose, and sucrose), starch and photosynthetic parameters (initial fluorescence, performance index on absorption basis, and turn-over number), and the number of nymphs at each of three infestations level (low, medium, and high) during both the vegetative and reproductive stage of the crop. In general, nymphs were more abundant during the vegetative stage. Starch content was strongly correlated with nymph density. A strong positive correlation was observed between fructose and nymph density during the vegetative stage. Among the photosynthetic parameters, the turn-over number N was positively correlated with nymph density at a low-infestation level and negatively correlated with nymphs when they occurred at a high-infestation level. B. tabaci feeding affected the plant’s physiology and its interaction is reflected in part by the relationships among photosynthetic parameters as well as the levels of sugars and starch. This understanding might be useful in developing better monitoring tools for pest management.