Effects of NeemAzal®-T/S in the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae) via food chain

Abstract

In times of mass occurrence, massive numbers of the outbreaking species serve as food sources not only to predators and parasitoids but also to scavengers and decomposers. One example benefiting from this process is the necrophagous guild, which depends on a carcass for nutrition and reproduction. A well-known outbreaking insect is the forest cockchafer Melolontha hippocastani F. It inhabits woodlands on sandy soils, the same habitat as Nicrophorus vespilloides Herbst—a common burying beetle feeding on a variety of animal carcass. In this regard, N. vespilloides may come in contact with plant protective agents applied to control M. hippocastani populations. In a laboratory trial, we studied sublethal effects of NeemAzal®-T/S on the reproductive output of female N. vespilloides. They were previously fed with cockchafers, which in turn had been fed with neem-treated leaves. It was shown that female beetles fed with ‘treated’ cockchafers were negatively affected in carcass burying behavior and egg-laying. Furthermore, reduction in larval hatching and survival during the parental feeding phase caused further diminution of the reproductive output. On the other hand, neither impacts on mean larval weights nor morphological malformations in N. vespilloides were observed. Transferability of the results into the field is discussed.