Seasonal Patterns of Reproduction in Two Species of Desert Beetles (Coleoptera: Tenebrionidae)

Abstract

Current literature on desert beetle activity infers that seasonality of beetle activity is temperature and rainfall dependent, reflecting reproductive activity. In this study 2 desert tenebrionid beetles were compared. Eleodes hispilabris Say fits the expectations for reproduction, gaving 1 reproductive bout coincident with rainfall. Eusattus muricatus LeConte, however, has at least 3 reproductive bouts during the activity period, only 1 of which coincides with rainfall. E. muricatus, although smaller, lays larger eggs than does E. hispilabris. Larger eggs may increase egg survivorship during suboptimal timing of oviposition by decreasing egg surface to volume ratios and thus minimizing desiccation. Larger nutrient reserves may increase survivorship of newly hatched juveniles. Gonadal effort by E. hispilabris was typical, i.e., females expended greater amounts of energy than did males. In E. muricatus, however, male gonadal effort exceeded that of females. This is discussed with respect to reproductive effort theory.