|Herrick, Jeffrey - Jeff|
Submitted to: Biotropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2000
Publication Date: 3/1/2001
Citation: GOULD, K.A., HERRICK, J.E., LEZAMA, H. REFUSE TO REFUGE: DRY SEASON USE AND MODIFICATION OF CATTLE DUNG BY SUBTERRANEAN TERMITES IN GUANACASTE, COSTA RICA. BIOTROPICA. 2001. V. 33(1). P. 121-130. Interpretive Summary: Cattle dung decomposition is an extremely important process in tropical pastures because it returns nutrients to frequently impoverished soils. Also, dung which does not decompose can kill the grass beneath it. During the course of this and several related studies, we discovered that termites, rather than dung beetles, are the most important dung decomposers sin a seasonally-dry tropical pasture in Costa Rica, and that dung appears to be a preferred food source for these termites. We also learned that the termites tend to be concentrated nearer to the surface under dung patches. Although neither species of termite is a mound builder, these termites use specialized behaviors to exploit and modify dung patches so that foragers have access to concentrated food resources and partial protection from the dry climate and from their invertebrate predators, essentially using dung patches as a "found mound".
Technical 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 and Hoplotermes sp. nov., during the 1991 dry season in Guanacaste, Costa Rica. The densities of termite foragers of both species were evaluated in cattle dung patches, in the soil beneath each patch (litter, 0 to 3.5 cm and 3.5 to 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 per bait plot and only 8 (3) +/- 11 individuals per 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 cm microsite. In control areas, however, Amitermes was most abundant in the 3.5 to 7 cm microsite. Amitermes and Hoplotermes were found in 35 and 9 of the 54 control plots, respectively. We believe 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 invertebrate predators.