There are two serious side effects which result from the use of most modern insecticides: the development of insect resistance to the treatment, and the nonspecific and broad-ranging killing effect of many such insecticides. These two side effects can, moreover, interact with one another to exacerbate the obvious practical problems they cause. When a broadly toxic insecticide is used to control a few specific insect pests, many of the other nontargeted insects affected by the treatment can develop resistance to it even though there was no need to kill them. Later, when there is a need to control the previously nontargeted insects, they will have likely become resistant to the insecticide to which they were previously exposed, and one option for their control will have been rendered useless. A considerable amount of research has accordingly been directed, and continues to be directed, towards solving these problems. See generally L. B. Brattsten, et al., Insecticide Resistance: Challenge to Pest Management and Basic Research, 231 Science 1255 (14 Mar. 1986).
There has been some interest shown in using fungi to control insect pests. For example, Hirsutella thompsonii has been suggested as a fungus useful as a mite control agent, (or a "mycoacaricide") in citrus rust mites. See, e.g., C. W. McCoy and T. L. Couch, 65 Florida Entomologist 116 (1982). It has been suggested that other types of fungi, such as fungi in the genus Entomophthora, might be useful as mycoacaricides because of the role they are believed to play in nature (See U.S. Pat. No. 4,021,306 to Soper; see also, U.S. Pat. No. 4,530,834 to McCabe), and there has been a considerable amount of basic research on the natural effects of these fungi on insect populations--including studies of the role of the fungus Neozygites floridana in regulating the population of various plant feeding mites. Exemplary of this research are R. L. Brandenburg and G. G. Kennedy, 34 Ent. Exp. and Appl. 240 (1983), R. L. Brandenburg and G. G. Kennedy, 74 Journal of Economic Entomology 428 (1981), and L. S. Boykin, W. V. Campbell and M. K. Beute, 77 Journal of Economic Entomology 969 (1984). This research has not brought forth a significant number of new mycoacaricides which can actually be applied to agricultural crops, or mycoacaricides which can confidently be said to be highly specific and selective in their action, even though there is a continuing need for such new, commercially useful, insect control agents.