INFLUENCE OF ELEVATED CO2 ASSOCIATED WITH CHICKPEA ON GROWTH PERFORMANCE OF GRAM CATERPILLAR, HELICOVERPA ARMIGERA (HÜB.)

Influence of increased CO2 concentrations (550 and 700 ppm) on host (Chickpea, Cicer arietinum L.) and its insect herbivore (Gram caterpillar, Helicoverpa armigera (Hub.)) was studied in relation to ambient CO2 (380 ppm) concentration under laboratory conditions. The foliar chemistry of chickpea under elevated CO2 revealed low nitrogen and high carbon content with increased C: N ratio but no change in phenol content. This alteration in food quality significantly affected the growth parameters of H. armigera in the form of increased food consumption, gain in larval weight and more fecal matter production. Larval duration was also extended by one day under elevated CO2 over ambient. Further, reduction in the fecundity (535 eggs/ female) was observed in the individuals raised under elevated conditions compared to ambient situation (580 eggs/ female). Diluted quality of food had a significant effect on growth performance indices of insect. Increase in approximate digestibility and relative consumption rate by the larva was observed under elevated CO2 situation. The reduced efficiency of conversion of ingested food (35.88 %) and digested food (37.88 %) was observed under similar situation. As a result, the relative growth rate was down by 5.22 % and 6.20 % under both elevated CO2 conditions. In a nutshell, it can be concluded that increased CO2 concentrations has the negative effect on the growth and development of H. armigera.