Practical Implications

Exploiting temperature for pest management is an attractive alternative to the use of pesticides. The manipulations can be safely administered and no harmful residues remain. Heat and cold treatments are emerging as the treatment of choice for quarantine treatment of fresh fruits and vegetables. Temperature treatment is especially popular in this industry because the major fumigant, methyl bromide, is being removed from the market due to its role as an ozone depleter. Soils and planting beds are being treated with heat, and both high and low temperatures are being used to treat houses and other structures. Stored grain can be effectively protected from insects with temperature treatments, and even some field crops can be protected with novel applications of heat applied directly to the plant.

Cold storage is used extensively to increase the "shelf life" of parasitic wasps and other biological control agents, as well as the hosts on which they are reared. The cryopreservation of embryos of D. melanogaster and other insects is a goal sought by numerous researchers. This ability could facilitate the long-term maintenance of valuable genetic stocks and reduce the care and expense required to continuously propagate insects used for research.

Insects have a wealth of behavioral and physiological responses to counter the effects of high- and low-temperature stress, and if temperatures are to be exploited for use in integrated pest management systems, these mechanisms must be either overridden or disabled. For example, the generation of thermotolerance can be prevented by applying heat stress in a nonoxygenated environment. Combination treatments that simultaneously apply both heat and anoxia or thermosen-sitization (application of two temporally separated treatments at moderately high temperatures) are especially attractive because they can cause mortality with less energy input. The low temperatures that prevail during winter are frequently just a few degrees above the insect's lower limit of tolerance. Attempts to further reduce the insect's body temperature by destroying the insect's protective winter habitat offer promise. Recent discoveries of ice-nucleating bacteria and fungi that are active on insects suggest new tools for manipulating the supercooling point. The diverse protective responses operating in insects suggest a similar richness of targets that could be rendered vulnerable to heat or cold injury.

See Also the Following Articles

Diapause • Hibernation • Temperature, Effects on Development and Growth • Thermoregulation

Further Reading

Bowler, K., and Fuller, B. J. (eds.) (1987). "Temperature and Animal Cells."

Society for Experimental Biology Symposium 41, Cambridge, U.K. Chen, C.-P., Lee, R. E., Jr., and Denlinger, D. L. (1990). A comparison of the responses of tropical and temperate flies (Diptera: Sarcophagidae) to cold and heat stress: J. Comp. Physiol. B 160, 543—547. Hallman, G. J., and Denlinger, D. L. (eds.) (1998). "Temperature Sensitivity in Insects and Application in Integrated Pest Management." Westview Press, Boulder, CO. Heinrich, B. (1993). "The Hot-Blooded Insects." Harvard University Press, Cambridge, MA.

Johnston, I. A., and Bennett, A. F. (eds.) (1996). "Animals and Temperature: Phenotypic and Evolutionary Adaptation." Society for Experimental Biology Symposium 59, Cambridge, U.K. Lee, R. E., Jr., and Denlinger, D. L. (eds.) (1991). "Insects at Low

Temperature." Chapman & Hall, New York. Somero, G. (1995). Proteins and temperature. Annu. Rev. Physiol. 57, 43-68.

Yocum, G. D., and Denlinger, D. L. (1994). Anoxia blocks thermotolerance and the induction of rapid cold hardening in the flesh fly, Sarcophaga crassipalpis. Physiol. Entomol. 19, 152-158.

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