Overview

The aim of the project is to quantify movements of predators between habitats in rice-onion cropping systems. Our hypothesis is that generalist predators can be found in rice-onion systems that play a role in maintaining control of insect pests. Habitats adjacent to the rice-onion system serve as reservoirs of generalist predators of insect pests. We have monitored the arthropod predators’ activity-density and directional movement between habitats in the fallow and rice system at four different farms in the province of Nueva Ecija. We are also assessing density and species composition in the field edge and at increasing distance from the field edge. We will continue this in the onion system when onion is planted in November to cover a full cropping cycle. Pitfall trap sampling at one location at IRRI serves as a control, and here we are also currently testing possible trap improvements. We have used directional pitfall traps placed in the bunds and sticky boards and window traps. Special emphasis is placed on spiders and coleopterans. We are analyzing the temporal patterns of the movements in and out the fields. Density of pests and natural enemies are assessed by visual count and suction sampling. This serves as a control of the catches in the pitfall traps. In addition, detailed biology and ecology of one or two selected generalist predators is being quantified in a combination of field and lab studies.