Effects of temperature on the predatory functional response of Arma custos adults to Spodoptera frugiperda

Author of the article:WANG Jie, MU Yin-Lin, YANG Can, YANG Lin, WANG Yu-Chuan, CHEN Jun-Zhu, CHANG Zhi-Min, LONG Jian-Kun,

Author's Workplace： Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Guizhou University, Guiyang 550025, China; Institute of Entomology, Guizhou University, Guiyang 550025, China; The Provincial Special Key Laboratory for Development and Utilization of Insect Resources, Guizhou University, Guiyang 550025, China; Bijie Technology Center, Guizhou Tobacco Company, Bijie 551700, China

Key Words：Arma custos; Spodoptera frugiperda; temperature; biological control; functional respone

Abstract：

[Objectives]  To clarify the effect of temperature on the ability of adult Arma custos to act as a biological control for 4th and 5th instar Spodoptera frugiperda larvae. [Methods]  The predatory functional responses of adult male and female A. custos to 4th and 5th instar S. frugiperda larvae were determined at 4 temperatures (18, 22, 26 and 30 ℃) in a laboratory. The density of 4th instar larvae was 5, 10, 15, 20, 25, 30 larvae/box, and that of 5th instar larvae was 5, 8, 10, 15, 20, 25 larvae/box. [Results]  The predatory functional responses of adult A. custos conformed to the Holling Ⅱ equation at each temperature. Temperature had a significant (F_{3, 16}=8.69, P<0.05) effect on predation, which increased at higher temperatures. Predation was also significantly (F_{5, 24}=5.53, P<0.05) higher at higher prey densities. The maximum rate of instantaneous attack of adult female A. custos on 4th instar larvae (0.812) was reached at 30 ℃, whereas that of adult males (0.721) was reached at 26. The maximum instantaneous attack rate of adult female A. custos on 5th instar larvae (0.937) was reached at  26 ℃, whereas that of adult males (1.233) was reached at 30 ℃. Maximum predation of female and male adults on 4th and 5th instar larvae (23.256, 21.834, 10.081 and 11.236, respectively) was reached at 26 ℃. The time required by adult males and females to process 4th and 5th instar larvae (0.043, 0.046, 0.099 and 0.089 d, respectively) was shortest at this temperature. [Conclusion]  The predatory capacity of adult A. custos with respect to 4th and 5th instar S. frugiperda larvae was highest at 26 and 30 ℃.