Effects And Preliminary Mechanisms Of L-arabinose To The Development And Feeding Preference Of Helicoverpa Armiger Larvae

The cotton bollworm Helicoverpa armiger(Hübner)(Lepidoptera: Noctuidae)is a polyphagous herbivore and distributes widely in China and all over the world.The main host plants include cotton,tobacco and maize etc.H.armiger can be reared by artificial diet.Sugar is an important source of energy for insects' development,and also an important signal substance of insect's feeding behaviors.L-arabinose is a normal sugar in plant,such as corn,sugar beets and apple.As a new low-calorie sweetener,L-arabinose has been widely used as food additives and weight-reduced drug for human being.L-arabinose can selectively inhibit the intestinal sucrase in mammals.Therefore,can L-arabinose have an affect on the growth of insects? In this study,the effects and the potential mechanisms of L-arabinose's on the development of H.armiger larvae were explored.The main results are as follows:(1)The feeding behaviors of 5th instar larvae of H.armigera can be affected by L-arabinose.The feeding preferences of 5th instar H.armigera larvae for L-arabinose were tested by using dualchoice leaf disc assays.It showed that caterpillars of H.armigera didn't prefer to feed on leaf dics treated by 1%,5% and 7.5% L-arabinose,respectively.(2)Aritificial diets with 3%,5% and 7.5% L-arabinose can significantly delay the larval development of H.armigera.The developmental period of caterpillars postponed with the invreasing of L-arabinose concentration in artificial diets.Compated with the control caterpillars feeding on normal diets,the body of caterpillars exposed to diets containing L-arabinose is short and thin.The weight of pupae which had been exposed to artificial diets containg 5% and 7.5% L-arabinose in larvae period exposed to artificial diet containing were significantly lower than that of the contral.(3)The glucose level in caterpillars could also been affected by L-arabinose in artifical diets.The concentration of glucose in midgut of caterpillars exposed to 1%L-arabinose was simiar to that in control caterpillars.However,the concentration of glucose in midgut of caterpillars exposed to 3%,5% and 7.5% L-arabinose was significantly lower than that of the control caterpillars.The glucose level in haemolymph of caterpillars exposed to any concentration of L-arabinose was similarto that of the control caterpillars.(4)The electrophysiological responses of sensilla styloconica in galea of larval mouthparts to L-arabinose were investigated using single sensillum recording technique.Four concentrations of L-arabinose,0.01 mmol/L,0.1 mmol/L,1 mmol/L and 10 mmol/L,were used as stimulus.But the L-arabinose sensitive receptor neurons have not been found in these sensilla yet.