温度和LED光源对夹竹桃天蛾幼虫行为的影响

Abstract

Insect behavior is expected to affect the degree of damage incurred by host plants. To investigate the effects of temperature and light wavelength on the behavior of Daphnis nerii( L.)( Lepidoptera: Sphingidae),the watching,walking,defecating,feeding,and resting behaviors of larvae were observed under standard laboratory conditions at five temperatures( 20℃,25℃,30℃,35℃,and 40℃) and under LED light sources of five different wavelengths( red,620—625 nm;yellow,580—585 nm; blue,465—467 nm; green,520—523 nm; and white,460—465 nm). The results showed that:( 1) Within each temperature condition,behaviors differed in frequency and total duration. For example,time devoted to resting was high at all temperatures; larvae spent more than 50% of the time at rest at 20℃,25℃,35℃,and 40℃.However,temperature influenced the frequency and time budget allocation of all larval behaviors. Resting was the most frequent behavior at 30℃,while watching and walking occurred more frequently than other behaviors at both higher and lower temperatures. Defecation constituted the least-frequent behavior at all temperatures except 40℃,while feeding was the least frequent activity at this temperature. The time budgets for watching,defecating,and resting at 30℃,for walking at25℃,and for feeding at 20℃ were lower than those of other behaviors.( 2) Within each light condition,behaviors differed in frequency and total duration. Among behaviors,defecation was allocated the least time in all light treatment conditions and no significant differences were observed for this behavior. However,light influenced frequencies and time budgetallocations for the remaining behaviors. Walking occurred less frequently under red,green,and white light than under yellow and blue light. The time budget allocated to resting was highest in red and white LED light,while that for walking was highest under green and blue light. The time budget allocations for watching and walking were lowest under white light,while the allocation for feeding was lowest under yellow light and that for resting was lowest under blue light. The frequencies of walking under white light,feeding under yellow light,and resting under blue light were lowest.( 3) The LED light treatments had different effects on larval behaviors in the 2-day experiment. Walking,watching,feeding,and resting behaviors all indicated a circadian rhythm in 16 L ∶ 8D conditions. In the red light treatment,all behaviors( except for watching on the second day) indicated a similar circadian rhythm. In the yellow light treatment,only walking showed a circadian pattern. Under blue and green light,none of the behaviors showed circadian patterns. These results indicate that temperature and light conditions have distinct effects on the behavior of D. nerii larvae. This information can serve as a resource for developing methods to predict the amount of harm incurred by host plants under different environmental conditions.