Carl, K.P. 1996 Ecological studies and prospects for classical biological control of apple pests in Europe and elsewhere.. IOBC/WPRS Bulletin 19(4): 67-74.

Notes: [This paper was presented at the International Conference on Integrated Fruit Production (Polesny, Muller & Olszak, Eds.) held at Cedzyna, Poland, 28 August - 2 September 1995.] Although IPM strategies have been developed in many apple growing regions of the world, in several areas the pesticide load is still heavy, IPM relies largely on reducing the excessive application of broad-spectrum pesticides and their replacement with more specific ones, the use of IGRs where permitted, and in some instances pheromones IOBC/WPRS working groups were instrumental in developing protocols to test the side effects of pesticides on nontarget and beneficial organisms and guidelines for integrated production of pome fruits in Europe. Some major natural control agents such as predatory mites and anthocorids received due consideration, and some biological control agents were deliberately used to alleviate specific pest problems (e.g. Prospaltella perniciosi against San José scale). In spite of all pest efforts, the effect of natural control and the use of classical biological control agents has been largely disregarded, a heritage from the days when a zero percent tolerance level was advocated and accepted as a standard that was prohibitive to the use of biocontrol agents. However, problems from increasing resistance to a decreasing number of registered pesticides warrant a novel approach. We now need to better understand and compare the ecology of natural control agents. Key issues would be investigations on the diversity and abundance of natural enemies in different regions and in relation to orchard management, varieties, etc. in order to enhance opportunities for biological control.