Synergistic, Natural Compounds as Insecticides

The Japanese beetle is a highly destructive pest of more than 400 plant species including fruits, vegetables, ornamentals, field and forage crops, and weeds. Since the first detection in the United States in a nursery near Riverton, New Jersey in 1916, it has spread to many states east of the Mississippi River (except Florida), as well as parts of Wisconsin, Minnesota, Iowa, Missouri, Nebraska, Kansas, Arkansas and Oklahoma. Despite regulatory efforts, by 2002 it had become established in at least 30 states. Of the states in the southern region, climatologic studies predict that it will eventually establish in all states bordering the Gulf of Mexico. Grubs (larvae) develop in the soil, feeding on the roots of various weeds and grasses, often destroying turf in lawns, parks, golf courses, and pastures. The insect has become the most widespread turf-grass pest in the United States. Efforts to control the larval and adult stages are estimated to cost approximately $460 million a year in management alone. Losses attributable to the larval stage alone have been estimated at $234 million per year; $78 million for control costs and an additional $156 million for replacement of damaged turf. Adults also feed on foliage and fruits of several hundred species of fruit trees, ornamental trees, shrubs, vines, and field and vegetable crops. Norway and Japanese maples, birch, crabapples, purple-leaf plums, roses, mountain ash, and linden are highly preferred ornamental hosts. While some woody plant species and cultivars have innate resistance against Japanese beetles, many economically-important plants can receive damaging levels of feeding and must be protected during Japanese beetle flight to prevent high levels of injury. Coleopteran pests are causing increased damage in fruit crops, as broad spectrum insecticides continue to be restricted through implementation of the Food Quality Protection Act (FQPA, 1996) passed by the U.S. Congress. At the same time as pest pressure is increasing from beetle pests, few new products are being registered in food crops, and those that are tend to be lepidopteran- and homopteran-specific. The lack of beetle-active products is creating a gap in pest management programs, making the development of new beetle-active insecticides a priority to enable fruit growers to meet productivity and quality targets. The registration of Admire (imidacloprid) in strawberry and blueberry during 2003 has provided a potential new option for grub control in some minor fruit crops, but this is an expensive option, with very specific requirements for application timing. Development of alternative reduced-risk larval controls for these and other pests would greatly improve the ability of growers to reduce beetle populations in and around their fields, and would help prevent yield loss and reduce contamination risk.