Water stress decreases the biocontrol efficacy of a nucleopolyhedrovirus against the fall armyworm on maize

Abstract

Drought events are expected to limit crop productivity in the context of current climate change. Drought is also likely to affect multitrophic interactions such as those involving plants, phytophagous insects and their natural enemies. We designed a two-phase experiment to test the effect of water availability and fertilizer treatment on the interaction between maize, the fall armyworm and its nucleopolyhedrovirus pathogen. Plants grown in soil with high irrigation and mineral fertilization had the highest shoot and root dry weight. Furthermore, plant nitrogen levels were higher in plants with fertilization and a low irrigation scheme compared to other treatments. Low irrigation of maize plants reduced virus-induced mortality of armyworm larvae. Insects did not feed on plants with high irrigation and without fertilization. We conclude that water stress and plant nutrition can affect virus performance and thereby affect the efficiency of biological control and pest management, especially as water and nutrient limitation will likely increase under climate change.

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