EFFECT OF IVERMECTIN IN SPATIO-TEMPORAL DYNAMICS OF DUNG BEETLE IN VERACRUZ, MEXICO

Abstract

Ivermectin-based anthelmintics are used in livestock systems of Mexico. However, its effect on the abundance, species distribution and spatial arrangement of dung beetles need to be explored. To estimate the effect of ivermectin, monthly collections were made from July 2008 to June 2009, in a pasture in central Veracruz. Ten pitfall traps were baited with manure (SI) and ten traps with manure plus ivermectin (CI). The data were analyzed using the MIXED procedure of SAS v. 9.1. By using the variance to mean ratio index and negative binomial´s K, we determined the spatial pattern through time. 4569 beetles were collected, belonging to the family Scarabaeidae, divided into three subfamilies Scarabaeinae, Geotrupinae and Aphodiinae, and 15 species, the most abundant were Digitonthophagus gazella F. and Euoniticellus intermedius Reiche, accounting for 65% of the individuals found. There were differences in the catches of six species of beetles, being lower in CI traps. E. intermedius, D. colonicus, and C. lugubris in june 2009. D. gazella and Ataenius cribithorax, presented lower captures in SI traps in october and november respectively. The beetles showed an aggregated spatial arrangement during the sampling period, having higher densities on the central and southeastern pasture. The presence of ivermectin in cattle dung did not affect the aggregation of dung beetles in the area of study.