Pengaruh perlakuan insektisida=Effect of Insecticide Treatment on Arthropod Diversity in Cabbage Cropping

The research was done in cabbage production center in Bantir Village, Sumowono District, Semarang Regency, and the Laboratory of Applied Entomology Gadjah Mada University, from May to October 2002. The objectives were: (1) to know the effect of insecticide treatments the diversity and abundance number and species arthropod in cabbage planted and (2) to know and to study the number arthropod diversity and species in cabbage. The experiment was done on 434 m2 area of field which was divided into two parts, each planted with cabbage. One part was treated with insecticide, the other was not. Each part was divided further into three plots of 72 m2, separated with the others by 2 m width divider planted with bean and fenced with 125 cm high plastic pieces. Arthropod population surveillance was done 8 times with interval of one week when the plants ages 15 to 64 days after planting. Sampling was taken with five methods: modified D-vac suction, sweep net, and direct observation for arthropod residing in plant canopypitfall trap for soil surface arthropodand Berlese funnel for soil borne arthropod. Arthropod population abundance was analyzed by using lognormal distribution and Shannon-Weiver diversity index. The result showed that regular application of deltamethrin insecticide (once a week) (1) reduced the population and the species number of arthropod, and (2) reduced diversity and abundance of the arthropod on cabbage planted. Keywords: diversity âarthropod âinsecticide âcabbag