LEDs for managing pest insects in greenhouses

Plant-eating insect pests cause significant economic loss in commercial greenhouse growing operations, sometimes amounting to tens of thousands of dollars per hectare. Insects as a vector of plant pathogens also rank very high on the problem list for greenhouse/hothouse growers. Integrated Pest Management is a pest control strategy that "uses an array of complementary methods: mechanical devices, physical devices, genetic, biological, legal, cultural management, and chemical management" to help or prevent these economic losses while significantly reducing the use of pesticides. Although host utilization by insects is broadly dictated by factors such as host species, season, plant nutrition, and water status, many insects that are significant economic pests in greenhouses, including thrips, aphids, and whiteflies use vision as a primary cue to orient to their hosts. Vision cues are predominantly related to color, or more specifically hue, color saturation, and brightness. Most insects studied have green, UV, and blue receptors, though red receptors have been found in some. Color can be used in two ways to protect crop plants, either as a mechanism to attract insects to traps or "decoy" plants, or to repel insects by interrupting the sequence that begins with their orientation to the plant from a distance and ends with establishment on the plant. A new revolution in horticultural lighting is underway with the development of solid-state lighting systems, the first lighting system that allows control of a lamp's spectral output. During research with plants in controlled environment rooms outfitted with red/blue light emitting diode (LED) arrays it was apparent that plant appearance was radically different than when observed under broad spectrum light sources. This led to the hypothesis that modifying lighting to change the appearance of plants might disrupt the ability of pest insects to locate and attack host plants, or inversely, that the appearance of decoy crops and physical traps could be enhanced to increase their effectiveness. This would allow the use of supplemental lighting systems that might already be in greenhouses to be used as a new tool in a grower's IPM program. The objectives of the proposed project is to identify solid-state lighting protocols that: (1) reduce predation of protected agriculture crops; (2) increase attraction to decoy crops; (3) enhance the attraction to physical traps (i.e., sticky cards); or (4) any combination of the above, while not disrupting beneficial insects or plant growth. If LED systems can be configured to help reduce insect damage and insect-related vectored diseases in greenhouses, these systems will gain additional usefulness by becoming an important component of the grower's IPM program, and could help to reduce the annual per hectare costs of greenhouse pest control.