Predation function and dispersal ability of Pheropsophus jessoensis against Spodoptera litura

【Objective】The aim of this study was to evaluate the predation potential of Pheropsophus jessoensison against Spodoptera litura,and provide reference for the application of P.jessoensis in the field to prevent and control S.li-tura.【Method】One adult of P.jessoensis which had been starved for 24 h was individually placed with 4^th-7^th instar larvae and pupae of S.litura with different density gradients in a glass Petri dish(15.0 cm diameter,2.0 cm high).The predation amount of P.jessoensis was counted,and statistical analysis was conducted using softwares such as SPSS 26.0,GraphPad Prism 8.0 and DPS 5.0 to elucidate the functional response and search effect of P.jessoensis towards larvae and pupae of S.litura.Additionally,the effect of intraspecific interference on the predation rate of P.jessoensis adults was clarified by quantifying the predation amount of P.jessoensis adults with different densities on 4^th-7^th instar larvae and pupae of S.li-tura of different densities.The crawling speed of P.jessoensis adults in different environments was also measured to deter-mine their dispersal abilities.【Result】The predation models of S.litura 4^th-7^th instar larvae and pupae by P.jessoensis adults followed a Holling II disk equation model.The daily average predation amount of S.litura 4^th-7^th instar larvae and pupae by P.jessoensis increased with increase of prey density,although the growth rate of predation gradually declined.The maximum number of prey consumed per day of P.jessoensis adults on the 4^th-7^th instar larvae and pupae of S.litura were 50.6,17.4,6.6,2.2 and 1.8 insects respectively,and the instantaneous attack rates corresponded to 2.079,1.354,1.279,1.619 and 1.504,with respective handling time of 0.013,0.032,0.098,0.383 and 0.468 d.The search efficiency of P.jessoensis adults on the 4^th-7^th instar larvae and pupae of S.litura was negatively correlated with prey density.As the prey density increased,the search efficiency deceased,with the highest search efficiency reaching a value close to 1.0.The competition intensity of P.jessoensis adults increased linearly with the increase of its density logarithm.The interference effect on the S.litura pupal stage showcased the highest intensity,with a maximum competition intensity reaching 0.5000.Conversely,the interference intensity on the S.litura larval stage decreased with the increase of instar.The crawling speed of P.jessoensis adults in different environments decreased significantly(P<0.05,the same below) with increasing com-plexity of environmental conditions,and was significantly greater on both the horizontal paper surface and the soil surface than on the horizontal ground surface and the vertical soil surface,with an average maximum crawling speed of 10.5 cm/s on the horizontal paper surface.【Conclusion】P.jessoensis can prey on the higher instar larvae and pupae of S.litura,with relatively high dispersal ability,and holds potential to control S.litura on a large scale.