Effects of environmental factors on phenotypic plasticity in Oedaleus decorus asiaticus

This study investigated the effects of three key environmental factors, population density, temperature and food availability on the plasticity of green-brown phenotypic of Oedaleus asiaticus under controlled laboratory conditions. Behavioral traits associated with different ecotypes were assessed to elucidate the influence of environmental variables on behavioral plasticity. Among the examined factors, population density had a significant effect on the body coloration of third instar nymphs (P < 0.05). Under certain conditions, the change rate of body coloration increased with density. At a density of 60 individuals per cage (0.25 m²), the phenotype change rate of third instar nymph of O. asiaticus was the highest, reaching 57.60%. However, at higher densities (80 and 100 individuals per cage), the rate of color transformation decreased to 54.89% and 51.20%, respectively. Temperature and food supply also had significant effects on the phenotypic variation of O. asiaticus (P < 0.05). When the temperature reached 40℃ under a 50% reduction in food supply, the rates of color change was 12.00% and 5.67%, respectively. Behavioral assays revealed that environmental factors had a significant impact on the number of turns and jumps of different types of O. asiaticus (P < 0.05). Solitary-type third instar nymphs exhibited 1.2~1.4 turns and 1.1~1.4 jumps per minute, whereas gregarious-type third instar nymphs exhibited 1.6~1.8 turns and jumps per minute. Therefore, the number of turns and jumps could be used as indicators to determine the behavioral changes of O. asiaticus. Notably, among the environmental factors tested, increasing population density was associated with heightened turns and jumps of third instar nymph of O. asiaticus. Collectively, these results indicated that both body coloration and behavior traits in O. asiaticus are shaped by the integrated effects of multiple environmental factors.