Lethal competition on joint predators during suppressing brown planthopper population

Abstract

Joint predator is one technique to control brown planthopper (Nilaparvata lugens) in the rice field by combining two or more predator species having a positive interaction. This study aims to determine the effect of joint predator density (Pardosa pseudoannulata and Phidippus sp) on competition and its predatory rate in suppressing the N.lugens population. The study used a completely randomized design (CRD) by combining P. pseudoannulata or Pp (1,2,3 individuals) and Phidippus sp or Ps (1,2,3 individuals) to become Pp1Ps1, Pp1Ps2, Pp1Ps3, Pp2Ps1, Pp2Ps2, Pp2Ps3, Pp3Ps1, Pp3Ps2, Pp3Ps3. The parameters observed were predation rate, bodyweight, mortality of both predators, and competition model. The results showed that the composition difference between P. pseudoannulata and Phidippus sp affected on competition model and the predation. The predation rate of joint predators at different densities ranged from 40.4 – 47.0 individuals of N.lugens (80.8-94.0%) in one-day observation, and they consumed all prey until the third day’s observation. The highest predation rate occurred for Pp3Ps3, but it was assumed it was not safe because of cannibalism and lethal competition. The Pp1Ps2 composition of joint predators was classified as safe, with 0 and 0.2 individuals’ mortalities and followed by draw competition between two predators.