Survey of testing methods

Other kinds of tests were performed in a cage, tunnel, or greenhouse and their objectives were to assess the consequences of sprays or residues on bees exposed to compounds in more or less standardized conditions. In these tests, scientists did not expect to estimate the reaction of an insect to a measured substance intake or deposit but to assess risk in practice. The advantage of keeping bees in such enclosures is to ensure the permanent exposure of the insects but the counterpart is an overestimate of the hazards. 

The third kind of assessment was hazard testing conducted in the field either by using domesticated non-Apis bees maintained in artificial domiciles or by monitoring native populations in their natural habitat. The drawback of these methods is that standardization is not possible since the exposure of experimental insects to test compounds is not controlled. In the case of native population monitoring, the main difficulty is the interpretation of data due to the number of factors involved in population changes during seasons and years. 

The first category will be referred below to as laboratory tests, the second as semi-field tests, and the third as field tests.  

The LD50 of several compounds was established in the social bee Trigona spinipes using a topical test protocol similar to the one for bumble bees [34], 

Laboratory tests were used to assess the effects of low doses or concentrations on bumble bees. To estimate whether a 0.01-0.02 j.g topical application of deltamethrin affected the longevity of bumble bees, 32 workers per treatment were kept in disposable boxes each containing eight insects, maintained in the dark at 20°C. Mortality was recorded daily [45]. A more recent article reported on a feeding test conducted on queenless microcolonies of three workers of B. terrestris to study sublethal effects of low concentrations of imidacloprid in the food on worker survival, brood size and larval development [46]. 

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A comprehensive survey of test methods is to be found in the Handbook of Polymer Testing (194). 

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