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674 or not it is in phase with the light-dark cycle. For example, in A. rumicis the incidence of diapause is increased by low nighttime temperatures and vice versa, though at very long day lengths (18 hours or more) temperature has little effect.

In most species studied diet influences the induction of diapause only slightly or not at all. In P. gossypiella, for example, the incidence of diapause induction may be increased by feeding the larvae on cotton seeds whose water content is low and/or oil content high, provided that the day length is not much greater than the critical value. Host-plant maturity can be correlated with the onset of diapause in a number of species though the chemical basis for this remains unknown. For some predaceous species (e.g., the convergent lady beetle, Hippodamia convergens), prey density is inversely correlated with the incidence of diapause.

For most insects termination of hibernation or estivation is not under photoperiodic control but occurs, under natural conditions, with the return of suitable temperatures for development. In a few species, however, exposure to appropriate photoperiods will terminate diapause. For example, in adult Leptinotarsa decemlineata and pupae of H. cecropia and P. gossypiella long-day conditions terminate diapause. Conversely, in some Limnephilus species (Trichoptera) that estivate as adults, diapause is ended by short day lengths.

In some species, especially those that overwinter in the egg stage or in a partially dehydrated condition, contact with liquid water is necessary for continued (i.e., postdiapause) development and activity. In diapausing larvae of O. nubilalis, for example, whose water content falls by midwinter to about 50% of the prediapause level, uptake of water (by drinking) is essential before the insect can continue its development (Beck, 1980). Lestes congener, a damselfly found on the Canadian prairies, oviposits in late summer in dry, dead stems of Scirpus (bulrush). The eggs begin to develop immediately but only to the end of anatrepsis and then enter diapause. Continued development in the spring will not begin until the eggs are wetted, regardless of temperature. Wetting is achieved under natural conditions as the level of the water rises during snow melt and also as a result of wind action, which causes ice movements and subsequent breaking and submersion of the plant stems (Sawchyn and Gillott, 1974a). As a result of such observations, it has frequently been claimed that water/moisture is a factor that terminates diapause. However, as noted above, in most instances it is unclear whether this is correct or whether in fact diapause has already ended; in other words, the insect is now quiescent but requires water for its continued development (Hodek, 2003).

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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