Stress-induced physiological changes in insects, alternative to pesticides

Stress induces release of neuroactive substances in insect blood. L-Leucine and its metabolite isoamylamine were concluded as neuroactive substances released in silkworm poisoned with DDT. Molecular design combining them with chemically active five-membered cyclic phosphate resulted in the finding of new insecticidal oxazaphospholidines. At sublethal doses, Insecticidal phosphorus compounds caused increase of octopamine titers accompanied with cAMP level Increase, trehalase activity suppression, and growth retardation in Tribolium castaneum larvae. Similar phenomena were also observed by the action of other chemical and physical stressors. Crowding, cold shock, and heat stress as well as JH-esterase inhibitors delayed pupation of Tribolium freemani larvae, and reduced JH-esterase activity. Isolation, light irradiation, vibration, and octopaminergic agonists as well as precocene accelerated the pupation, and increased JH-esterase activity. Ecdysteroid level was also affected by these stressors. Thus, a variety of physical stressors may represent safer alternatives to chemicals used In pest control. Octopaminergic agonists and antagonists may also be usable as insect growth regulators.