Transgenerational effect of host plant on growth and reproduction in two species of moth, Cacoecimorpha pronubana and Epiphyas postvittana (Lepidoptera: Tortricidae)

The carnation tortrix moth, Cacoecimorpha pronubana (Roelofs & Brown, 1982), and the light brown apple moth, Epiphyas postvittana (Walker, 1863) (Lepidoptera: Tortricidae) are two important polyphagous pest species affecting a wide range of plant species many of which are horticultural crops. Crop damage is caused by the larvae of these two moths rolling leaves together and feeding on the foliage. In order to understand how these two species are affected by a host plant through transgenerational dietary changes, we hypothesised that larval parental pre-treatment diet affects growth and reproduction of offspring. We tested the performance of developmental traits of C. pronubana and E. postvittana on three host plant species (larval diet treatment) – Prunus (Rosaceae), Choisya (Rutaceae) and Griselinia (Griseliniaceae). For the experiment we used larvae from a second generation of C. pronubana and E. postvittana reared either exclusively on Prunus, or reared exclusively on Griselinia (pre-treatment). Regardless of whether moths had been reared on Prunus or Griselinia both species of host plant had a significant average effect on the duration of larval development and the pupal size of both species of moth, for E. postvittana, and for C. pronubana. Although, neither pre-treatment, nor treatment had a significant overall effect on fecundity (number of eggs per clutch laid) in either species of moth, there was a significant interaction effect observed between the pre- and post-treatment on fecundity for both species of moth. Our results suggest that changes of host plant species composition can affect the performance of offspring of both these polyphagous pest species intergenerationally in complex ways which are relevant to agroecosystems. Such phenomena may be important when developing new strategies for the integrated pest management of these two important pest species