Associations Between Testes Size and Polyandry in Illinois Magicicada spp.
Type of Presentation
Poster Session
Location
University Library
Start Date
4-9-2026 2:00 PM
End Date
4-9-2026 3:15 PM
Abstract
Periodical cicadas (Magicicada spp.) are distinctive insects due to their 13–17-year life cycle and short adult emergence, during which reproduction takes place for 4-6 weeks. While their life cycles and behaviors are well-studied, relatively little is known about their mating patterns, specifically whether Magicicada exhibit polyandry. This study examined whether testes size in male cicadas reflects reproductive investment consistent with levels of female remating by taking absolute and relative measurements on testes area and dry mass in male M. cassini, M. decula, and M. decim from the 2024 Brood XIII. Linear regressions assessed the relationship between head width and testes size, while single-factor ANOVAs compared relative testes size among species. Relative testes size did exhibit variation, with M. cassini and M. decim having proportionally larger testes than M. decula, suggesting higher sperm competition in these species. Weak correlations between body size and testes size indicate that reproductive investment is not solely determined by relative body size. These findings suggest that M. decula may experience lower levels of sperm competition compared to M. decim and M. cassini, reflecting potential differences in mating frequency among Magicicada species.
Faculty / Staff Sponsor
Melissa Plakke
Associations Between Testes Size and Polyandry in Illinois Magicicada spp.
University Library
Periodical cicadas (Magicicada spp.) are distinctive insects due to their 13–17-year life cycle and short adult emergence, during which reproduction takes place for 4-6 weeks. While their life cycles and behaviors are well-studied, relatively little is known about their mating patterns, specifically whether Magicicada exhibit polyandry. This study examined whether testes size in male cicadas reflects reproductive investment consistent with levels of female remating by taking absolute and relative measurements on testes area and dry mass in male M. cassini, M. decula, and M. decim from the 2024 Brood XIII. Linear regressions assessed the relationship between head width and testes size, while single-factor ANOVAs compared relative testes size among species. Relative testes size did exhibit variation, with M. cassini and M. decim having proportionally larger testes than M. decula, suggesting higher sperm competition in these species. Weak correlations between body size and testes size indicate that reproductive investment is not solely determined by relative body size. These findings suggest that M. decula may experience lower levels of sperm competition compared to M. decim and M. cassini, reflecting potential differences in mating frequency among Magicicada species.