Refuse to Refuge: Dry Season Use and Modification of Cattle Dung by Subterranean Termites in Guanacaste, Costa Rica1

Abstract

Baits and soil cores were used to quantify temporal variation in the use of cattle dung by two species of subterranean termites, Amitermes beaumonti Banks and Hoplotermes sp. nov. (hereafter referred to by genus), during the 1991 dry season in Guanacaste, Costa Rica. The densities of termite foragers of both species were evaluated in cattle dung patches (baits), in the soil beneath each patch (litter, 0–3.5 cm, and 3.5–7 cm), and in the same layers from adjacent dung-free control sites. Dung patch and control plots were sampled 3, 10, 60, or 110 days after 1450-ml dung patches were deposited on the pasture. Amitermes foragers were abundant in 3-, 10-, 60-, and 110-day-old dung patch plots with a mean (median) ± SD of 100 (59) ± 120 individuals/bait plot, and only 8 (3) ± 11 individuals/control plot. Hoplotermes foragers were less abundant, with a mean of 22 (0) ± 87 individuals in dung patch plots and 2 (0) ± 9 in control plots. Hoplotermes was most abundant in the surface litter under 10-day-old dung patches, where an average of 39 (0) ± 105 individuals were found. In association with dung patches, Amitermes density was highest inside or directly beneath the dung patch and lowest in the 3.5- to 7.0-cm microsite. In control areas, however, Amitermes was most abundant in the 3.5- to 7.0-cm microsite. Amitermes and Hoplotermes were found in 35 and 9 of the 54 control plots, respectively. We believe that the high termite densities associated with cattle dung patches can be explained by the energetic and microclimatic requirements of the termites and the physical structure of the dung. Although neither species of termite is a mound builder, these termites use specialized behaviors to exploit and modify dung patches such that foragers have access to concentrated food resources and partial protection from the dry climate and from their invertebrate predators.