Observation and evaluation of predatory behavior of Harmonia axyridis on Spodoptera frugiperda

Objective  To investigate the predation potential of the natural enemies, Harmonia axyridis, to Spodoptera frugiperda.

Method  The predation behavior of H. axyridis was observed in laboratory, and the predation abilities of H. axyridis adults and the 4^th instar larvae to the 1^st and 2^nd instar larvae of S. frugiperda were evaluated.

Result  The predatory behaviors of H. axyridis on S. frugiperda larvae included five behaviors of stationary, searching, testing, feeding and crawling. H. axyridis adult appeared three pairs of feet grasping its prey when preying on the 3^rd instar larva of S. frugiperda. The predation function responses of H. axyridis adults and the 4^th instar larvae to the 1^st and the 2^nd instar larvae of S. frugiperda were accorded with the Holling II model. For the 1^st instar larvae of S. frugiperda, the maximum daily predation amounts of adults and the 4^th instar larvae of H. axyridis were 196.08 and 161.29 individuals respectively, the rates of instantaneous attack were 1.390 6 and 1.451 4 respectively, and the handling time were 0.005 1 and 0.006 2 days respectively. For the 2^nd instar larvae of S. frugiperda, the maximum daily predation amounts of adults and the 4^th instar larvae of H. axyridis were 65.36 and 41.84 individuals respectively, the rates of instantaneous attack were 1.145 7 and 1.271 0 respectively, and the handling time were 0.015 3 and 0.023 9 days respectively. The predation abilities of H. axyridis adults to S. frugiperda larvae were stronger than those of the 4^th instar larvae of H. axyridis.

Conclusion  H. axyridis has certain potential control ability on S. frugiperda and can be used for the prevention and control of S. frugiperda.