INFLUENCE OF HOST PLANTS ON THE AGE-SPECIFICLIFE HISTORY TRAITS OF PARASITOID TRICHOGRAMMA CHILONIS (ISHII) A BIO-CONTROL AGENT OF THE LEPIDOPTERAN PEST HELICOVERPA ARMIGERA (LEPIDOPTERA: NOCTUIDAE) EGG DENSITIES

Abstract

The pod borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is considered to be the most important pest in several crops such as chick pea (Cicer arietinum L.), Pigeon pea (Cajanus cajan L.) and Tomato (Lycopersicum esculentum L.) in North-East Uttar Pradesh, India. Extensive and indiscriminate use of chemical insecticides against pest caused severe effect on both soil health and environment, therefore effective bio-control agent (BCA), is generally perceived as providing both long-lasting insect pest control and negligible damage to the environment and non-target organisms. The aim of the present study is to control the pest population of H. armigera at Gorakhpur district by using effective bio-control agent. The age-specific life-table statistics of the parasitoid were observed at five different host densities (10, 25, 50, 100 and 200 eggs/female/day). It was found that the values of age-specific survival rate (lx) of T. chilonis increased progressively when more and more host eggs exposed to the female parasitoid throughout their life-span. It was highest at 200 host-density for all the host plants. The age-specific net fecundity rate (mx) was found to be host densities dependent. It appears that at low host density egg laying tendency of the female compel her to lay eggs in a previously parasitised egg. The longevity of the female were significantly (P < 0.001) correlated with host density. The data obtained from the present study will used in the development of management strategies for the control of H. armigera on host crops.