Sentinel cattle and a grid of swormlure-baited sticky traps were used to monitor a Malaysian population of the Old World screw-worm fly, Chrysomya bezziana Villeneuve. Observations were carried out on an isolated cattle station at monthly intervals during the period August 1996 to June 2000. The number of flies caught was unaffected by weather conditions at the time of trapping, but was positively correlated with the total rainfall and the average daily air temperature prevailing 15-28 days earlier, when trapped flies were still juveniles. Trap catches were biased in favour of females, but daily catch rates of both sexes increased significantly the longer traps were open, suggesting that efficacy was related to the differential volatility of the chemicals comprising swormlure. Oviposition on sentinel cattle occurred mostly in late afternoon or early evening but increased significantly as the wound aged. Oviposition rates were positively correlated with female catch rates, but the relationship was curvilinear, suggesting that fly populations may be subject to some form of density-dependent constraint. Consistent differences in oviposition rates on sentinel cattle at different localities on the cattle station suggested the existence of highly clumped, quasi-stationary populations. Differences in trap catches between traps located in pastoral areas and those sited in nearby oil palm or rubber plantations supported this interpretation of the data. These findings are discussed in relation to the use of the sterile insect technique for the control of screw-worm fly infestations.
Key words: Population, stem borer and natural enemiesIn India maize crop is being attacked by about 139 species of insect pests with varying degree of damage. However, only about a dozen are quite serious (Sarup et al. 1987, Siddiqui andMarwaha 1993). Among them some important lepidopteran stem borers seriously limit potentially attainable maize yields by infesting the crop throughout its growth, from seedling stage to maturity. Seventeen species in two families (Pyralidae and Noctuidae) have been found to attack maize in various parts of Africa. However, Chilo partellus (Swinhoe), Chilo orichalcociliellus Strand, Busseola fusca Fuller, Sesamia calamistis Hampson, and Eldana saccharina Walker are of great importance. The yield losses caused by stem borers to maize vary widely in different regions and range from 25-40% according to the pest population density and phenological stage of the crop at infestation (Khan et al. 1997).Among them maize stem borer, C. partellus is most dominant contributing 90-95 per cent of the total damage in kharif season (Jalali and Singh 2002). Despite of, intensive work done in India on C. partellus yet, the work in Jammu region is lacking. As this pest is becoming a major problem in sub mountainous region of Jammu, yet distribution and intensity of infestation of this pest has not been studied therefore; it is imperative to study population patterns and natural enemies associated to this pest. To achieve this objective, a multi directional light trap was operated from 1800 to 0600 hours daily. The collections were made weekly throughout the crop seasons of 2006 and 2007. Infestation of stem borer was determined by counting the total number of dead hearts and the leaf damage in each selected plot at weekly interval. Total number of healthy and infested plants was counted in each plot during each week and means of three selected locations were calculated.It was evident that stem borer appeared in the light trap in 21 st week (6 adults), when the mean maximum and minimum temperature (25.70 and 14.95ºC) with relative humidity (63.50 %) (Table 1). Maximum traps (47 adults / trap) were observed in 29 th week, when average maximum and minimum temperature (29.25 and 16.45ºC) with relative humidity 82.6%. After 35 th standard week, number of adults decreased gradually to 3 moths/ trap in 41 th standard week when the maximum and minimum temperature (23.34 and 12.54ºC) with relative humidity of 67.61%. Thereafter no catch was observed. The adult population was positively correlated with weather parameters viz. relative humidity (r=0.908, P<0.01) maximum (r=0.501, P<0.05)and minimum (r=0.484, P<0.05) temperatures.Results clearly indicate that initially adult population tends to increase in summer months and decreases further till onset of winter season. Such results might be attributed due to hibernation of larvae into the stubbles and maize stalks. These findings are supported by Kumar (1984), Singh et al. (1985) and Kfir (1988) who found that overwintering larvae causing infestation hibernate...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.