Plant-associated fungi affect above- and belowground pest responses to soybean plants

Abstract

Aim:The objective of this research was to screen fungal isolates originally isolated from cotton plants and measure their effects on the interactions between soybean and two aboveground pests (cabbage looper; Trichoplusia ni and soybean looper;Chrysodeixis includens) as well as a belowground pest (soybean cyst nematode; Heterodera glycines).Methods and Results: For aboveground pests, we measured the leaf area consumed and larval weight. For our belowground pest tests, we measured shoot height, shoot fresh weight, root fresh weight and number of cysts. Out of the 50 fungal isolates tested, we tested 30 fungi in the interaction with cabbage looper, 36 for soybean looper, 41 for soybean cyst nematode. We tested 23 isolates against all pests and identified multiple isolates that significantly changed the response of pests on inoculated soybean plants versus controls. Conclusions:We identified three fungal isolates that significantly reduced both leaf area consumed aboveground by caterpillars and number of cysts produced belowground by nematodes. These isolates were an Epicoccum italicum, a Chaetomium undulatum and a Stemphylium majusculum. Significance and Impact of Study:Overall, this study provides important insights into plant-fungal interactions and their effect on both above-and belowground pests. This study also highlights an important first step towards harnessing the potential of microbial inoculates as a tool for integrated pest management in soybeans.