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Hexane wash of gallery and body of Opisina arenosella Walker elicited positive response from the parasitoids namely Goniozus nephantidis (Muesebeck), Brachymeria nephantidis Gahan and Elasmus nephantidis Rohwer, in terms of more number of parasitoids entering the kairomone arm than hexane arm in 'Y' tube olfactometer. Although, numerically, the gallery wash elicited higher response than larval body wash of the host O. arenosella to G. nephantidis, statistically, the treatments were on par. Chemical analysis of kairomonal substances using GCMS revealed the presence of 13-tetradecenal and myristic acid in the gallery wash, in addition to dodecane, pentadecane, hexadecane, heptadecane, eicosane and tricosane. Larval wash showed terpenoids like alpha-terpinene and alpha humulene.

Since Goniozus nephantidis (Muesebeck) is found to have strong parental care for its progeny, the influence of different densities of G. nephantidis and its host, Corcyra cephalonica (Stainton) on the behaviour ecology of the parasitoid was studied. Interaction between different densities of the host and parasitoid revealed that a ratio of 1:1 was significantly superior to all other ratios resulting in maximum parasitism (9.0 larvae / female), fecundity (93.2/female) and number of progenies (75.2/female). Exposing more than one C. cephalonica larva did not significantly increase the parasitizing efficiency, fecundity and progeny produced. Conversely, exposing a single C. cephalonica larva to several female parasitoids adversely affected the biological attributes of the parasitoid. Increasing the densities of either host insects or parasitoids had an inverse relationship with oviposition behaviour, parasitism efficiency and progeny production of the parasitoid establishing the important and significant role played by host-parasitoid density.

Black-headed caterpillar, Opisina arenosella (Walker), is a serious pest of coconut palms causing severe defoliation and yield loss. Goniozus nephantidis (Muesebeck), one of the dominant and effective parasitoids of O. arenosella, is being widely used in the biological control programme. Technology for the production and cost economies of G. nephantidis were worked out for the first time. The production of 3,25,000 parasitoids within a period of 6 months required charging of 225 wooden Corcyra boxes @ 75 nos./batch three times. Coreyra cephalonica (Stainton) was used as a laboratory host for rearing the parasitoid. Exposure of 2500 matured C. cephalonica larvae, was required in order to get I lakh parasitoids per month. The cost of production of 100,000 G. nephantidis cocoons was Rs. 27,600. The commercial cost of cocoon in India is Rs. 40,000 per 100,000 parasitoids and the profit would be Rs. 12,400 for producing 100,000 parasitoids. Benefit-Cost of the production of parasitoid was 1:1.45. Employment generated during the production process was four. Hence, this technology is highly feasible and can he adopted for the production and use against the pest. This mass production technology would be suitable for promoting localized production of G. nephantidis at village or district level especially for farmers, unemployed graduates, private and public sector units and NGOs.

Many entomophagous insects attack the black-headed caterpillar of coconut, Opisina arenosella Walker during its developmental stages. Goniozus nephantidis (Muesebeck) is a gregarious larval parasitoid of O. arenosella. During summer months of 2003-04 and 2004-05 the parasitoid was evaluated in the field in Kerala by following two methods - trunk and crown release that were compared with control. There was significant reduction in the population of O. arenosella after third to sixth releases in treated palms, when compared to control palms. There was no significant difference between the two methods of release of G. nephantidis in reducing the population of O. arenosella. Hence farmers could easily and effectively adopt the trunk release method.

Parasitoids have the potential to suppress populations of their hosts and thus may play an 2 important role in influencing the temporal and spatial dynamics of pest arthropods. 3 Behavioural interactions between foraging females, collectively constituting ‘mutual 4 interference’, can reduce host suppression. We use laboratory microcosms to assess the 5 prevalence and consequences of mutual interference behaviour in a bethylid wasp, Goniozus 6 nephantidis (Muesebeck) (Hymenoptera: Bethylidae), which is known to brood guard and to 7 engage in agonistic contests for individual hosts and which is also an agent of biological pest 8 control. We hold host and parasitoid numbers constant and vary the degree of female-female 9 contact that can occur. Mutual interference is manifest in a considerable reduction in the 10 number of offspring produced when females are not fully isolated from each other, due to 11 effects operating at the early stages of offspring production. This mutual interference may 12 contribute towards the limited degree of host population suppression achieved when some 13 species of bethylids are deployed as agents of biological pest control and also has clear 14 potential to influence the efficiency of mass rearing of parasitoids prior to field release.