Impact of Pesticides
Many pesticides (insecticides, fungicides and herbicides) are toxic to beneficial organisms, including insect pollinators. This is because beneficial organisms are generally more susceptible to chemicals than the target pest species.
Many factors influence the toxicity of pesticides to beneficial insects and mites, and much care is needed when integrating the use of chemicals and beneficial organisms in IPM programmes. The effect of pesticides can also be modified by application practices and environmental conditions, so, even though a chemical may generally be regarded as ‘safe’, how and when it is applied and the conditions under which it is applied may make it less safe to beneficial organisms.
Besides the contact action of a pesticide resulting from direct spray contact, the ongoing action of pesticide residues may be harmful to beneficial organisms. The residues of many insecticides can kill beneficial insects and mites after very short exposures on the leaf or soil surface. Even when the killing power of a chemical declines as the residues disappears, sub-lethal effects, e.g., reduced reproduction, disrupted prey searching and capturing behaviour can also impact on the action of beneficial organisms.
Chemicals that are not normally applied to control insects, such as fungicides, can also have a negative effect on beneficial insects and mites. Therefore, it is important to consider all pesticides that will likely be used on a crop before beneficial organisms are introduced, and select only those that are known to be less disruptive.
‘The Good Bug Book’ Second Edition (2002), Editor Richard Llewellyn, provides a list of commonly-used chemicals and their likely toxic effects on beneficial insects and mites, and the period or waiting time which should be allowed to pass following a pesticide application before introducing beneficial insects and mites into a crop.
Refer to the label on pesticide containers for specific information about the safety of that product to beneficial insects and mites.
Guiding principles for integrating the use of pesticides and beneficial insects and mites