Effects of elevated CO2 on the foraging behavior of cotton bollworm, Helicoverpa armigera

Abstract

Effects of elevated CO2 on the foraging behavior of cotton bollworm Helicoverpa armigera Hubner reared on milky grains of spring wheat grown in ambient, 550 αL/L and 750 αL/L CO2 concentration atmospheres in open-top chambers (OTC) were studied. The results indicated that: (i) elevated CO2 significantly affected both the type and amount of food eaten by H. armigera reared on milky grains of ambient CO2-grown wheat were significant higher than those for bollworm larvae reared on wheat grains grown in 550 and 750 αL/L CO2 atmospheres; (ii) when bollworm larvae were reared on mixed milky grains from different CO2-grown wheat (food-choice condition), larval duration increased significantly - pupal weight, adult longevity, and fecundity decreased significantly, comparing with those reared on milky grains of ambient CO2-grown wheat, 550 αL/L CO2-grown wheat and 750 αL/L CO2-grown wheat respectively; (iii) significant decreases in the contents of fructose and gross protein (GP) and significant increases in the contents of glucose, amylose, total saccharides (TSC), TSC: GP ratio, free amino acids and soluble protein in the wheat grains with CO2 rising; (iv) and selected-foraging amount/food-choice index of cotton bollworm H. armigera were significantly positive correlated with the contents of fructose and GP of wheat grains, but they had significantly negative relationships with the contents of glucose, amylose, TSC and TSC: GP ratio of wheat grains.