Comparative Morphogenic and toxicity Studies on the Effect of Pesticides on Honeybee Brood

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Abstract
Toxicological and morphogenic studies were carried out to determine the potential hazard to honeybee (Apis mellifera) brood of pesticides which have contaminated the food in the hive. Pesticides were added to the food in individual brood cells using a microsyringe. Precise qualitative and quantitative monitoring of the pesticide effect throughout the brood cycle and into the adult stage was possible. Each pesticide was tested at three or more dosages, on worker larvae 1–2, 3–4 and 5–6 days old, for effects on mortality and on amorphogenic changes. Linear regressions were used to construct dosage-mortality curves. Results indicated that mortality may occur at any stage of larval, prepupal or pupal development and to emerging or newly emerged adults. Some adults that survived were light in colour, and of light weight, and often had deformed wings or no wings; they were weak and died soon after eclosion. Of the 31 pesticides tested by the morphogenic technique, six were eventually non-toxic, 19 were simple poisons, and six were both poisonous and amorphogenic. Some were less toxic, some equally toxic and some more toxic to brood than to adults. Studies are in progress to determine usage, dosage, timing of application, and substitution strategies to decrease the hazard of pesticides which contaminate brood food in the hive.