VIII SIMPOSIO INTERNAZIONALE ICPBR

HAZARDS OF PESTICIDES TO BEES

Bologna, 4-6 Settembre 2002

Metodologie dei test e studi sugli effetti dei pesticidi sulle api

The effects of spinosad, a naturally derived insect control agent to the honeybee (Apis mellifera)

Mark Miles

Dow AgroSciences, Wantage, OX12 9JT, U.K. E-mail: mjmiles@dow.com

Spinosad is a novel insect control agent derived by fermentation of the Actinomycete bacterium, Saccharopolyspora spinosa. Spinosad controls many caterpillar pests in vines, pome fruit and vegetables (including tomatoes and peppers), thrips in tomatoes, peppers and ornamental cultivation and dipterous leafminers in vegetables and ornamentals. Application rates vary between 4.8 and 36 g of active substance per hectolitre (g as/hL) depending on the target pest. It is important that plant protection products are authorised for use only in ways which do not pose an unacceptable risk of harm to honeybees. For this purpose testing was performed to enable the safety of spinosad to be evaluated.

The effects of spinosad to honeybees has been extensively researched. Testing has been performed under a variety of conditions in a range of countries globally. Studies to determine the acute toxicity of spinosad under laboratory conditions were conducted to generate LD50 or LC50 values for oral and contact routes of administration. These demonstrated that spinosad was highly toxic to worker honey bees under worst case laboratory conditions and that the oral route of exposure provided the greater risk.

Residue tests conducted under laboratory, semi-field and field conditions on worker honey bees foraging on treated foliage indicated that dry product residues were harmless. Therefore the effects seen in the laboratory acute toxicity tests did not translate to a more realistic exposure scenario indicating that safe use patterns for the product can be developed. Semi-field cage studies have also demonstrated that spinosad was safe to bees when applied to flowering crops during periods of bee activity. The majority of studies conducted have indicated that spinosad does not adversely affect honeybee behaviour, brood or queen.

It can be concluded that spinosad when used according to good agricultural practice would be safe to foraging worker bees, queen and brood. Additional levels of safety could be achieved by avoiding situations were bees would forage primarily on aphid honey dew.