Use of Food and Space by Tunneler Dung Beetles (Coleoptera; Scarabaeinae) During Reproduction

Abstract

At two temperate pasturelands in northern Mexico, we explored possible competition for food and space under pats during the simultaneous nesting periods of the univoltine species Dichotomius colonicus (Say), Phanaeus quadridens (Say), and Copris sierrensis Matthews. To simulate unlimited resources, 50 5-kg cow dung pats were placed at regular distance intervals in each pastureland. After building trenches around the pats, the number and depth of each nest, as well as larval development status, were documented once for a period of 1-8 mo. Analyses of variance and association tests were used to make a between-site comparison of dung pat occupation, nests occupied per species, nests per dung pat, and nest depth below each pat. The proportion of pats occupied by each species differed significantly between sites. C. sierrensis colonizing most pats at one site and D. colonicus at the other. There were no differences between sites in the frequency of pats occupied by more than one species. The association test and Ochiai index showed that each species colonized dung pats independently. The results suggest that pat occupation depended on their location by beetles and the relative abundance of each species. The species tended to dig nests at different depths, possibly reducing interspecific competition for space. It can therefore be concluded that, when food resources seem to be unlimited, they are shared following a "lottery dynamic" model if there is spatial differentiation among species.

Size-dependent seasonal activity for males of the dung beetle Copris acutidens (Coleoptera: Scarabaeidae)

“…Of nests observed during the reproductive period in this study, approximately 18% were colonised by C. acutidens. This would not be considered a low colonisation rate, given that it was noted in a previous report that colonisation rates of dung pats experimentally placed in a temperate region inhabited by three large tunneller dung beetles were 40-82% (Huerta et al 2010). In the reproductive nests, more major males than minor males stayed in nests with females when the morphs were distinguished by horn length, whereas there was no difference in the proportion of minor and major males that stayed in nests with females when the morphs were distinguished by body size.…”

Annual Abundance and Population Structure of Two Dung Beetle Species in a Human-Modified Landscape

“…According to Hanski and Cambefort [51], the adult feeding behavior required to reach sexual maturity and the search for mates also occur during seasons with optimal environmental conditions. Several studies suggest that the life cycle of dung beetles, especially the nesting and emergence of new individuals (tenerals) is primarily modulated by temperature and precipitation as well as the availability of food [40,52,53]. Our results and those observed in the tropical dry forest [54,55] suggest that the activity of dung beetles decreases considerably during the most climatically severe seasons of the year, such as during the dry season or when temperatures are low.…”