Mass-rearing and life history of <i>Cyclocephala barrerai</i> (Coleoptera: Melolonthidae) and congeneric species

A major challenge in studying the biology of the Melolonthidae has been the lack of a consistent supply of organisms with known characteristics. This study aimed to develop a methodology for mass-rearing a Cyclocephala barrerai Martínez (Coleoptera: Melolonthidae) colony over several laboratory generations. The mass-rearing was initiated with eggs from wild-collected adults; each developmental instar was reared under conditions suited to their environmental and nutritional needs. Insect survival, egg-adult cycle length, sex ratio, adult weight, and number of eggs laid by each female were recorded for each generation. The morphology of mass-rearing organisms was compared to that of the wild-collected specimens. A second cohort of organisms from the original generation was reared under identical conditions and their survival, duration, and morphometry of each larval instar were recorded weekly. These data were then compared to those from the original group to assess the impact of constant manipulation during the larval instar. The mass-rearing methodology proposed in this work successfully reared 3 generations of C. barrerai with an overall average egg-adult survival rate of 66.6%. The egg-adult cycle length, proportion of females and males, and average weight differed among generations. The F1 organisms presented similar morphometrics to those collected in the field. Manipulation significantly reduced insect survival. Mass-rearing of C. barrerai facilitates a comprehensive study of its biology and may establish the species as a model for the Melolonthidae. This methodology establishes the foundations for rearing congeneric species in the laboratory.