Stored grain insects are unique in that most of the major species are cosmopolitan and readily move about in domestic and international trade. Hence, resistant strains are also moving throughout the world, reaching countries where resistance had not been suspected. Fumigation has long been regarded as a basic method of controlling stored product insects and one which would be of material assistance in delaying the development of resistance to the unrelated residual pesticides. The method itself, by virtue of the low variability in response of individual insects to the commonly-used materials such as methyl bromide, is also usually considered to be less prone to resistance development than the normal methods with residual pesticides. It is disturbing then to note the increasing prevalence of resistance to fumigants and the resultant weakening of one of the most powerful tools available in stored product pest control for delaying or preventing development of resistance. The emergence of resistance to fumigants under practical conditions is a matter for particular concern. With major world dependence on fumigation both as a routine disinfestation treatment and as a means of combating insecticide-resistant strains, the occurrences reported, although as yet limited in number and often at marginal resistance levels, are of considerable significance and pose a real threat to a continued ability to store grain safely.
Only about 1% of the applied pesticide actually reaches the target pest. The other 99% enters the ecosystem. The ecological impact of pesticides has been well documented and the list includes the near extinction of the peregrine falcon, osprey, and bald eagle, as well as many other creatures. A less well-known but far-reaching effect of pesticides is on bee populations. As early as 1944, there was evidence that pesticides were seriously affecting honeybee and wild bee populations.