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Latebreaking Poster

Session: Population Dynamics And Regulation (Latebreaking)

LB 35-292 - Complex Effects of Temperature and Intraspecific Competition on the Body Size and Lifespan of Callosobruchus maculatus

Thursday, August 10, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Though body size and lifespan are thought to be linked through the size-fitness hypothesis, previous studies have not examined this relationship when multiple biotic and abiotic variables act in concert. We investigated how temperature and intraspecific competition jointly affect the body size and lifespan of Callosobruchus maculatus, a pest of stored legumes. We hypothesized that C. maculatus exhibits scramble competition; that temperature and competition will synergistically reduce body size; and that larger-bodied individuals will have longer lifespans. We measured body size, developmental period, and lifespan of newly emerged beetles whose parents were assigned to one of five parental density treatments across seven different temperatures spanning 18-36°C. We report three main findings: first, there is a negative relationship between development time and body size, confirming that C. maculatus experiences scramble competition. Second, we found that temperature and larval competition both decrease body size, but temperature has a stronger effect except at temperatures exceeding 27ºC. Finally, we found no significant association between body size and lifespan. Given that this beetle is detrimental for storage of dry legumes, these findings are relevant to food security and pest management practices. Due to the conserved nature of life history trait responses to temperature, how temperature and competition affect C. maculatus body size can inform us of the ecological consequences of climate change in other ectotherm systems.