Transgenerational effects induced by plant’s anti-herbivory defenses

One mechanism by which parents can increase their progeny's fitness is through transgenerational effects, the transmission of traits or responses from parents to offspring influenced by environmental factors encountered by the parental generation. Certain traits, such as short generation times and limited dispersal, foster a strong autocorrelation of habitat conditions across generations, thereby increasing parents' ability to predict their offspring's environmental conditions, enhancing these effects. Parental nutrition is a significant driver of transgenerational effects, impacting multiple offspring traits. Therefore, plant quality alterations due to the induction of anti-herbivory defenses can affect both the herbivorous insects and their progeny.
We explored whether defense-induced plant quality changes trigger adaptive transgenerational effects in Colorado potato beetles (Leptinotarsa decemlineata). First, we examined how induced defenses affect adult reproductive success and whether they promote parental provisioning via intraclutch cannibalism. We then used a reciprocal design to assess whether offspring benefit from environmental matching across generations and how cannibalism influences larval development.
Induced defenses reduced adult oviposition and larval growth but also triggered transgenerational effects. Offspring of parents fed on defended plants showed higher intraclutch cannibalism, improving larval growth, particularly on induced plants. Larvae also performed better when reared on the same plant type experienced by their parents, pointing to additional transgenerational adaptations.
Focusing on plant-induced defenses, our study broadens the spectrum of environmental factors influencing transgenerational effects. Additionally, the transmission of phenotypic traits across generations is added to a diverse array of strategies developed by insect herbivores in their enduring coevolutionary arms race with plants.