Impact of Biotic and Abiotic Stress on Survival of Lac Insects Kerria lacca Kerr. on Pigeonpea (Cajanus cajan (L.) Millsp)

Abstract

Cajanus cajan is generally grown in rainfed condition. The crop is also a good annual host plant of lac insect. C. cajan is widely reported to have biotic stress due to insect pests on it. Lac insect is phloem sap feeder and hence imparts biotic stress. The present field study was conducted to evaluate the percent survival of lac insects on C. cajan by adjusting different levels of biotic and abiotic stress on the host plant. The biotic stress due to insect pests on C. cajan was minimised with periodic spray of contact insecticides. The varying level of biotic stress i.e., No, Low, Medium, and High level was maintained on C. cajan plants with lac insects on it. The three levels of abiotic stress in this experiment were considered in terms of soil moisture stress. It was managed through irrigation per plant through drip system, it was considered that creating different levels of moisture stress in soil will impact the host plant. The abiotic stress was of three levels i.e., Low, Medium, and High. The result reveals that survival percent of Lac insect from brood lac inoculation to the harvest of lac crop was highest 37.52 percent on C. cajan with one primary branch and its secondary branches with lac insect (L1- Low biotic stress). It was 32.13 percent (W3- Low soil moisture stress). The study indicates that biotic and abiotic stress play a major role in the survival of K. lacca.