Effect of the secondary substances from wheat on the growth and digestive physiology of cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae)

Yu WANG,Ying HAN,Qing-Wen ZHANG,Qing-Nian CAI

doi:10.14411/eje.2006.030

Abstract

Three secondary compounds, pyrocatechol, gramine and ferulic acid from wheat were separately incorporated into artificial diets and fed to cotton bollworm Helicoverpa armigera (HĂźbner) larvae to determine their effects on larval and pupal weights and the nutritional indices of the larvae. The results show that these three secondary compounds can decrease the mean larval and pupal weights of cotton bollworm, with the mean larvae weights differing significantly between treatments. Mean pupal weight was only significantly reduced by ferulic acid and gramine, but not pyrocatechol. There were significant correlations between mean larval weight and concentration of the three secondary compounds tested, and between mean pupal weight and concentration of ferulic acid and gramine. The three secondary compounds tested affected the nutritional indices of cotton bollworm larvae differently. Compared with the control, ferulic acid and gramine significantly decreased RGR (the relative growth rate), AD (approximate digestibility) and ECD (conversion efficiency) of cotton bollworm larvae, and pyrocatechol only reduced ECD. All three indices were the lowest for cotton bollworm larvae fed on the diet with gramine (0.0984 ± 0.0114 g/g/day, 14.2670 ± 1.1541% and 31.1337 ± 1.1213%).

Highlights

Cotton bollworm is one of the most important pest insects in many countries of world and is responsible for destroying a lot of crop plants
Pyrocatechol and ferulic acid were separately dissolved in distilled water and in 70% ethanol and incorporated into the artificial diet of the cotton bollworm at a concentration of 0, 0.12, 0.33, 0.46, 0.78 or 1.57 mg/g and less than 1% ethanol
The mean larval weight of cotton bollworm fed the diet with different concentration of pyrocatechol was lower than the control at 0.33, 0.78 and 1.57 mg/g concentrations, but higher at the 0.12 mg/g concentration (Fig. 1a)

Summary

Introduction

Cotton bollworm is one of the most important pest insects in many countries of world and is responsible for destroying a lot of crop plants. In 1990s, the cotton bollworm caused serious damage around the world, which resulted as a huge reduction in cotton production. In north China 1st generation cotton bollworm larvae mainly injure winter wheat in the late stage growth with 90% of the eggs of the 1st generation oviposited on wheat ears (He et al, 1996; Xia et al, 1997). The larvae mainly feed on wheat ears. One larva can destroy approximately 47.7 grains (Wang et al, 1997b). The cotton bollworm infestations of wheat are an important source of pests which infest cotton and other crops after the wheat is harvested (He et al, 1996; Wang et al, 1997b)

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