Summer Diapause Syndrome

The external conditions that insects must tolerate differ sharply in summer and winter. Aestivating and hibernating insects may show similar diapause syndromes: cessation of growth and development, reduction of metabolic rate, accumulation of nutrients, and increased protection by body coverings (hard integument, waxy material, cocoons, etc.), which permit them to endure the long period of dormancy that probably is being mediated by the neuroendocrine system.

Migration to aestivation sites is another component of diapause syndrome found in some species of moths, butterflies, beetles, and hemipterans. In southeastern Australia, the adults of the Bogong moth, Agrotis infusa, emerge in late spring to migrate from the plains to the mountains, where they aes-tivate, forming huge aggregations in rock crevices and caves

Seasonal Cues

Summer diapause may be induced obligatorily or facultatively by such seasonal cues as daylength (nightlength) and temperature. When it occurs facultatively, the response to the cues is analogous to that for winter diapause; that is, the cues are received during the sensitive stage, which precedes the responsive (diapause) stage. The response pattern is, however, almost a mirror image of that for winter diapause (Fig. 2). Aestivating insects themselves also may be sensitive to the

FIGURE 1 Bogong moths, Agrotis infusa, aestivating in aggregation on the roof of a cave at Mt Gingera, A. C. T., Australia. [Photograph from Common, I. (1954). Aust. J. Zool. 2, 223-263, courtesy of CSIRO Publishing.]

physiogenesis clearly distinguish summer diapause from winter diapause, suggesting that despite the superficial similarity in their dormancy syndromes, the two types of diapause involve basically different physiological processes.

See Also the Following Articles

Cold/Heat Protection • Diapause •

Dormancy • Migration

Further Reading

Common, I. F. B. (1954). A study of the biology of the adult Bogong moth, Agrotis infusa (Boisd.) (Lepidopera: Noctuidae), with special reference to its behaviour during migration and aestivation. Austral. J. Zool. 2, 223-263.

Furunishi, S., Masaki, S., Hashimoto, Y., and Suzuki, M. (1982). Diapause response to photoperiod and night interruption in Mamestra brassicae (Lepidoptera: Noctuidae). Appl. Entomol. Zool. 17, 398-409.

Hinton, H. E. (1960). Cryptobiosis in the larva of Polypedilum vanderplanki Hint. (Chironomidae). J. Insect Physiol. 5, 286-300.

Masaki, S. (1980). Summer diapause. Annu. Rev. Entomol. 25, 1-25.

Matthée, J. J. (1951). The structure and physiology of the egg of Locustana pardalina (Walk.). Union S. Afr. Dept. Agric. Sci. Bull. 316, 1-83.

Tauber, M. J., Tauber, C. A., and Masaki, S. (1986). "Seasonal Adaptations of Insects." Oxford University Press, New York.

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