Abstract: 【Aim】 Cannibalism could facilitate the infection of certain pathogens that can be transmitted by feeding on infected conspecifics. This may have potential applications in the control of pests by entomopathogens. Our study aims to explore the relation between cannibalism and age and nutrition in larvae of the cotton bollworm, Helicoverpa armigera. 【Methods】 We estimated the incidence of cannibalism of H. armigera larvae by feeding different concentrations of sodium to a laboratory population and a wild population, and examined whether dietary sodium had any effects on the cannibalism. 【Results】 The survival rates of the larvae of H. armigera were the lowest when the tests were initiated at the beginning of the 3rd and 4th instars, statistically significantly increased when the experiments were carried out at the beginning of the 5th instar, and further raised when the experiments were performed at the beginning of the 6th instar. Moreover, the survival rates of the larvae fed on normal diet prior to experiment were the highest, and slightly but distinctly decreased when the larvae fed on sodium-deficient diet. In addition, the pupation rates of the larvae were similar, irrespective of whether the larvae fed on normal or sodium-deficient diets, and whether the experiments initiated at the beginning of the 3rd, 4th, 5th or 6th instar. 【Conclusion】 The results demonstrate that for H. armigera  larvae cannibalism highly occurs in the 4th and 5th instars rather than the 3rd and 6th instars, and to some extent, sodium deficiency enhances cannibalism. This study provides a basis for further work in this field.

Key words: Helicoverpa armigera , larva, cannibalism, larval instar, nutrition, sodium