The selection of oviposition sites by female moths is crucial in shaping their progeny
performance and survival, and consequently in determining insect fitness. Selecting
suitable plants that promote the performance of the progeny is referred to as the
Preference−Performance hypothesis (or ‘mother‐knows‐best’). While root infestation
generally reduces the performance of leaf herbivores, little is known about its impact
on female oviposition. We investigated whether maize root infestation by the Western
corn rootworm (WCR) affects the oviposition preference and larval performance of the
European corn borer (ECB). ECB females used leaf volatiles to select healthy plants
over WCR‐infested plants. Undecane, a compound absent from the volatile bouquet of
healthy plants, was the sole compound to be upregulated upon root infestation and
acted as a repellent for first oviposition. ECB larvae yet performed better on plants
infested below‐ground than on healthy plants, suggesting an example of ‘bad motherhood’.
The increased ECB performance on WCR‐infested plants was mirrored by an increased
leaf consumption, and no changes in the plant primary or secondary metabolism were
detected. Understanding plant‐mediated interactions between above‐ and below‐ground
herbivores may help to predict oviposition decisions, and ultimately, to manage pest
outbreaks in the field.
