6533b85afe1ef96bd12b89c6

RESEARCH PRODUCT

Field application of the juvenile hormone analogue fenoxycarb against hopper bands of Locusta migratoria capito in Madagascar

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Summary Field trials have been carried out to examine the suitability of the JHA fenoxycarb in locust control. Laboratory tests have shown that a variety of JHAs, including fenoxycarb, applied to last instar larvae increased mortality, induced morphogenetic defects during metamorphosis, reduced fertility and provoked solitarisation of gregarious hoppers. The phase shift was indicated by green coloration and the acquisition of morphological and behavioural characteristics typical for solitary locusts. The present field experiments should clarify whether or not the effects observed in the laboratory are also observed with hopper bands in their natural habitat and if swarm formation and emigration from the recession areas can be prevented. The results from the topical application (ultra light volume (ULVJ method) of six hopper bands of different sizes and composition (in respect to developmental stage of hoppers and their phase expression) with a broad range of fenoxycarb doses were quite comparable to those obtained in the laboratory. Colour transition started at day 2 after treatment It was obvious that coherence and marching behaviour were strongly disturbed. Even the lowest dose applied, 50 g a.i./ha, caused a whole array of morphogenetic dcfccts impairing jumping and flight. Fitness in general was greatly reduced, making the treated animals more vulnerable to many predators. Although a quantitative evaluation of the field trials, especially concerning mortality, was not possible, it was shown unequivocally that fenoxycarb exhibited the same activity profile as in the laboratory tests at a reasonably low dose. Thus, further field trials with even lower doses and quantitative calculations are of interest.