Ground beetle assemblages (Coleoptera, Carabidae) and plant dwelling non-target arthropods in isogenic and transgenic corn crops

Abstract

This paper reports the results of a two-year field study aimed at a
better understanding of the influence of transgenic com on non target entomofauna,
with particular emphasis on the community structure and biodiversity of a
typical soil fauna like Coleoptera Carabidae. A comparison was made of ground
beetle assemblage abundance, community structure and the degree of specific
biodiversity in transgenic and conventional com crops. A total of 3,768 individuals
belonging to 42 species were collected from sowing to harvest time over a
two year period. The Carabidae faunal composition and the individua! species
abundance varied more according to the spatial and tempora! distribution rather
than to the maize hybrid. Different indexes of biodiversity (Index of Shannon-
Weaver H', Hill's numbers: N0, N1, D, N2, Ninf• hierarchical richness index HRI,
Index of Pielou J') and similarity (Sorensen's index QS) were applied to the data.
Although there was little biodiversity in the Carabidae communities throughout
the study period there was no effect due to the transgenic com.
Consideration was also given to the effects of transgenic com crops on plant dwelling
non-target arthropods that normally live on com plants; and other insects
living in dose contact with these or with the European Com Borer ( Ostrinia nubilalis),
such as Hymenoptera parasitoids and Diptera Syrphidae. Statistica! analyses
revealed no significant differences in the abundance of plant dwelling non-target
arthropods in conventional com and transgenic com.