Larval Crowding Did Not Enhance Adult Migration Propensity in Spodoptera frugiperda

Abstract

Reproduction and flight are two major adaptive strategies to cope with environmental stress in migratory insects. However, research on density-mediated flight and reproduction in the global migratory agricultural pest Spodoptera frugiperda is lacking. In this study, flight and reproductive performances in response to larval crowding were investigated in S. frugiperda. We found that larval crowding significantly reduced the pupal and body weights of S. frugiperda. Adults reared under the highest density of 30 larvae/jar had the minimum wing expansion, which was significantly smaller than that of larvae reared under solitary conditions. Larval crowding also significantly increased the pre-oviposition period (POP) and period of first oviposition (PFO) but decreased the lifetime fecundity, flight duration and flight distance. Our results showed that S. frugiperda reared under solitary conditions exhibited higher pupal and body weights and stronger reproductive and flight capacities than those reared under high-density conditions. Larval crowding did not enhance the migration propensity in S. frugiperda adults. In conclusion, larval crowding may not be a major factor affecting FAW migration due to high levels of cannibalism. These findings provide new insights into the population dynamics of S. frugiperda under larval crowding conditions.

Environmental stress during larval development induces DNA methylation shifts in the migratory painted lady butterfly (Vanessa cardui)

“…Both the abundance of food and the density of competing conspecifics could inform the developing larvae about the expected future availability of host plants. Higher larval rearing densities seem to enhance flight phenotypes in most, but not all, Lepidoptera and other insects showing migration tendencies (Du et al, 2022; Jiang et al, 2011; Lü et al, 2022; Parker & Gatehouse, 1985).…”