The effect of diet on midgut transcriptome and resulting changes in infectiousness of AcMNPV baculovirus in Trichoplusia ni

The cabbage looper, Trichoplusia ni, a global generalist lepidopteran pest, has developed resistance to many synthetic and biological insecticides, requiring effective and environmentally acceptable alternatives. One possibility is the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). This baculovirus is highly infectious for T. ni, with potential as a biocontrol agent, however, its effectiveness can be strongly influenced by dietary context. In this study, transcriptomics were used to examine how the virulence of this virus was affected when T. ni larvae were raised on different diets: cabbage, potato, and artificial diet. Differential gene expression in 4th instar larval midguts was correlated with larval susceptibility to virus between diets. We found 1,985 differentially expressed contigs for cabbage vs artificial diet, 1,118 for potato vs cabbage, and 1,753 for potato vs artificial diet. Susceptibility of larvae raised on potato was significantly lower compared to larvae raised on cabbage or artificial diet.