Quantitative Survey of Population Trends of Heliothis Armigera and its Natural Enemies on Various Plants in Hyderabad Distt

Abstract

Present studies on the quantitative survey of Population trends of Heliathis armigera and its natural enemies on various host plants in Hyderabad district were conducted during a period of one year and four months i.e., from 1.9.1988 to 31.12.1989. during this period a detailed systemic survey of host plants was carried out in 4 Talukas of Hyderabad district which were Hyderabad, Tando Allahyar, Tando Mohammed khan and Hala. In each Taluka, target sites were selected and the crops grown there were weekly observed. During study period it was observed that H. armigera occurred mainly on gram, Tomato, Berseen, Soybean, Sunflower, Maize, Cotton, peas, Spinach, and Brinjal crops. A very minor attack of the pest was recorded on other crops i.e., Lucern, pigeon, peas, ground nut, Sorghum, Rose and chillies. The young larvae of H. armigera caused damage to gram crop during December to March, and attacked tender foliage, flower buds, flowers and developed seeds in the pods. The attack was severe during Feb, and March. It attacked the leaves, stem, flowers, and fruits of tomato crop during January to April. The caterpillars occurred on maize during Dec. to March and bored through tender cos and other softer parts of the top of stem and made large holes in the whorls of leaves. In Barseem crop the pest attacked the young leaves, stem, flower heads, and seeds. The severe attack of pest was observed during the month of March. In cotton the young larvae of H. armigera infested leaves, tender shoots, flowers, squares, small bolls and mature bolls. The peak infestion on cotton was recorded during the months of July and August. The pest was found attacking on leaves, flower heads and seeds of sunflower crop. The maximum infestation was observed during November to January in all parts of the district. Similarly on safflower the damage was caused by the larvae of H. armigera during months of Feb. to April. The larvae soon after hatching fed on growing leaves and tender shoots and later on they damaged flowers and capsules by eating seeds inside. The soybean crop was attacked by H. armigera during the month of May to July. The larvae infested leaves by cutting outer margins and making holes in them. Later on, they attacked green pods and fed on seeds inside. The pest attacked potato crop during October to January and during infestation period the young larvae attacked potato leaves throughout the growing period. On spinach the caterpillars attacked young leaves and made scratches in the middle portion of leaves. The pest attack on this crop continued during January to March. Similarly, the pest attacked peas during December to March. The larvae attacked leaves, flower heads and seed pods of peas. The Brinjal crop was also attacked by H. armigera. The pest appeared on this crop during April to June and damaged young leaves and young and mature fruits of the crop. A large number of adult moths were collected on light traps during September to June. Maximum number of moths were trapped during March, April, October and November moths which indicates that the pest completed 4 generations in one year. Two species of parasitoids were recorded as larval parasites of H. armigera. They were compoletis chloridea and Apanteles sp. The Maximum parasitism was recorded as 13.0%