| Streszczenie: | This study was conducted on two pasture located on the coast of the State of Veracruz, Mexico, where the warm, very humid climate is marked by spring rains. The two ranches are contiguous, with similar vegetation, but they used different management approaches to pasture and livestock over the course of the study. On the first ranch, livestock were treated with vermicides, and pasture with herbicide, after which the pasture was burned. On the second ranch, neither livestock nor pasture received such treatments. The herbicide used on the first pasture (Picloram and 2,4-D) was applied in July and August, at the time that Ataenius apicalis emerges. This treatment was damaging to the species, reducing population levels effectively to zero during July, while on the second pasture, more than 2,000 A. apicalis individuals were collected. The herbicide application did not adversely affect Ataenius sculptor, which emerges later in November. The vermicides applied to livestock (Levamisol, or Ivermectin and Clorsulon) had a slight negative effect on population levels of both species, which the subsequent burning slightly enhanced. On the first ranch, Digitonthophagus gazella and Euoniticellus intermedius were also adversely affected, mainly by the herbicide; no individuals of either species was found there between July and September, while both species were always found on the second ranch. Nothing could be concluded about the vermicides' effects on these insects.
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