Effect of monosodium glutamate on apple leaf consumption by codling moth larvae
2002
Pszczolkowski, M.A. | Matos, L.F. | Zahand, A. | Brown, J.J.
We have demonstrated that larvae of codling moth, Cydia pomonella (L) can successfully complete their first instar when fed apple leaves instead of fruit. Larvae fed leaves after hatching maximized their feeding intensity (about 320 microgram/larva/day) on day 2. Weight gain revealed a stereotypic sigmoid pattern that peaked on day 3. Although the maximum body weight of larvae fed leaves was 70-85% less than for larvae maintained on apples or on artificial diet, 100% of larvae fed leaves molted to the second instar 3-5 days after hatching. Our investigation revealed a diurnal pattern of leaf ingestion, and neonates' feeding intensity decreased significantly during the scotophase. We also demonstrated that monosodium glutamate (MSG) increased feeding on leaves by codling moth larvae. Depending on the duration of the bioassay, and larval age at time of initial exposure, 0.05 mg/ml and 0.1 mg/ml MSG increased apple leaf consumption by 25-60% over leaves alone. The effect of monosodium glutamate was best demonstrated during the first day following hatching. Exposure to MSG also accelerated molting to the second instar. Larvae exposed to MSG initiated consumption of leaf tissue significantly earlier than control neonates. The feeding stimulatory effect of MSG was not observed if exposure to this chemical was delayed until 3-4 h after hatch. The addition of feeding stimulants to pesticides that act via the alimentary tract may reduce the amount of active ingredients needed to maintain the efficacy of these formulations. Here, we postulate that first instar codling moth larvae are potential targets for treatment with pesticide formulations enhanced with monosodium glutamate.
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