The Effect of Water Level on the Survival and Rice Damages by Black Beetle (Heteronychus lioderes Redtenbacher)

Abstract

Black beetle, Heteronychus lioderes is a new insect pest of rice, it infests and damages Kao Dok Mali rice variety in broadcasting rice field in many provinces in Tung Ku La Rong Hi area where is the important of Jasmine rice production of Thailand. The insect damages seriously in rice stem during drought period. The objective is to study the water levels affect the insect survival and its destruction in rice stem. Completely randomized design (CRD) with 4 treatments and 4 replications was designed. The adult insects were released into each rice growing cylinder with 4 different water levels namely 8, 4, 2 and 0 (control) centimeters, above soil surface. After insects were being released for 3 days, the survival was 30% in cylinder which had 8 centimeters water level and the survival was decreased to 5 % after being released for 5 days but no symptom of theirs damages on rice stem. At the same time after the insects were being released for 3 days the rice stems were totally damage to 100% and insect survival was 100% even though they were released for 5 days. The result showed that water levels significantly affected the insect survival. The higher water level above the soil surface, the higher insect death obtained but the lower rice stem damaged.