Assessment on voracity and predation by predator, sycanus dichotomus stal. (Hemiptera: Reduviidae) to oil palm bagworm, pteroma pendula

Abstract

Sycanus dichotomus Stal. (Hemiptera: Reduviidae) is a generalist predator with a wide prey spectrum that commonly preys on bagworms and nettle caterpillars in oil palm plantations in Malaysia. The voracity of fifth instar nymphs and adults (males and females) of S. dichotomus using Pteroma pendula Joannis (Lepidoptera: Psychidae) third instar larvae as prey was evaluated in the laboratory, as well as its relationship with the development stage and exposure time on the voracity and predation rate. The number of preys consumed by predators was recorded at every 3, 24 and 48 hr intervals. The maximum voracity and predation rates were always greater in adults. The adult females displayed the highest prey consumption (1.0- 4.33 bagworms) followed by adult males (0.67-4.17 bagworms), and fifth instar nymphs (0.5-3.0 bagworms) at all time intervals. Although the fifth instar nymphs were able to kill the prey offered, the differences in predation potential indicated that the adult males and females were more vigorous and voracious in capturing and killing prey compared to the fifth instar nymphs. Results showed that the overall effect of the developmental stages of S. dichotomus on voracity and predation rate was highly significant (F = 10.420; df = 2; P <0.001). Similarly, the time intervals also exhibited a highly significant effect on the voracity and predation rate of S. dichotomus (F = 95.267; df = 2; P <0.001). However, the relationship between the predator developmental stages and exposure times was not significant (F = 2.444; df = 4; P = 0.300). This finding indicates the potential of the adults' stage of S. dichotomus to be released in the field, aiming for greater bagworm reduction in subsequent generation. In future research, it is necessary to assess the dynamic features of prey-predator system in an actual oil palm field.