Population Dynamic of Brown Plant Hopper, Predators and Neutral Insects in Irrigated Rice of Yogyakarta after Insecticides Application

Abstract

Brown Plant Hopper (BPH) infestation in irrigated rice agroecosystem resulted yield loss. The application of insecticides by farmers are usually excessive, reducing pest population and negatively affecting the predators. This research aimed to define the impact of insecticides on the population dynamic of BPH, predator and neutral insects which influenced rice yield. Research was conducted at Yogyakarta, Indonesia, during May to September 2021. Randomized Block using four replications was applied. Rice varieties Inpari 32 HDB and Inpari 42 GSR were planted. Insecticide with active ingredient spinetoram 120 g/l and triflumezopyrim 106 g/l were applied to the rice plant on day 40th then pimetrozin 50% was applied at day 50th. Results showed that BPH population was reduced from 30-50 nymph per 30 plants to 10 nymph at day 12th after pimetrozin 50% application or at the day 2nd after spinetoram and triflumezopyrim insecticides application until day 50th. In contrast, BPH population in all insecticide plants was significantly lower than in all control and did not increase until harvest. On the other side, predators such as Paederus sp and Coccinelids were not affected by all insecticides, except Ophionea sp, Spiders and Cythorinus sp. However, their population recovered at day 30th after first insecticides application. Within the fluctuated population of BPH, rice productivity of Inpari 32 HDB and Inpari 42 GSR applied with insecticides were 9.52 ton ha-1 and 10.60 ton ha-1, while Inpari 32 HDB control and Inpari 42 GSR control 9.44 ton ha-1 and 10.72 ton ha-1