Life History and Habits

After emergence, immature adult Odonata spend some time away from water, usually among trees or tall grass where they hunt for prey and become sexually mature. It is during this maturation phase that some Odonata migrate over long distances. The maturation period, which lasts anywhere from a few days in smaller species to a month in large dragonflies, is followed by the reproductive phase in which mating and oviposition occur. Usually these two processes occur at the same site, although this is not necessarily so.

Mature adult Odonata generally can be classified as "perchers" or "fliers," the former spending most of their time perched and making only short flights, while the latter, when active, fly continuously. Adults feed throughout their life, Zygoptera often catching stationary prey whereas Anisoptera mostly capture their prey in flight, occasionally aggregating in large numbers where prey is concentrated. Males of many species are territorial, that is, they occupy and defend an area against other males. Perchers have a base from which they undertake patrol flights or sallies against intruders while fliers patrol the area continuously for extended periods. Other species show little or no spatial territoriality, though may behave aggressively against conspecifics they encounter, a feature that ensures the spacing out of males within a habitat. Some fliers are territorial for several short (10-40 minutes) periods throughout the day, between which they leave the area, allowing other conspecific males to occupy the space. Should a receptive female conspecific enter the territory and be recognized by the male (probably using visual cues), he will attempt to mate with her. Using his legs the male grasps the female on the pterothorax, then curls his abdomen around so as to be able to grip the female's prothorax (Zygoptera) or head (Anisoptera) with his claspers (the tandem position). As noted above, the compatibility of the male and female structures are key determinants of the conspecificity of the partners. The male's legs then release their grip, and the female bends her abdomen forward until its tip contacts the accessory genitalia on the male's second and third abdominal segments (the wheel position) (Figure 6.9). Earlier, it was assumed that the sole purpose to this was the transfer of sperm from male to female. However, in probably all species that settle after taking up the wheel position, the major portion of the time spent in copulation (which may last up to 30 minutes) is taken up by the male's penis removing much (40-100% depending on the species) of the sperm of a previous mating from the female's bursa copulatrix and spermatheca, before insemination occurs. Sperm displacement also occurs in the libel1ulid Erythemis (Lepthemis) simplicollis where copulation lasts less than 20 seconds. Whether the phenomenon is widespread among species that copulate for such brief periods (usually in flight) or whether sperm packing occurs (sperm from earlier matings is pushed more deeply into the spermatheca while that of the most recent mating remains adjacent to the spermathecal opening so that during oviposition it is used preferentially) requires further study. Certainly, however, the structures of both the penis and the female storage organs in some anisopteran families are very different from those of Zygoptera which have been

mostly studied, suggesting that sperm packing may be more common in Anisoptera (Waage, 1984).

Oviposition usually occurs soon after copulation, and in many Odonata the male remains close to (hovering or perching nearby) or in tandem with the female, the intensity of the association being correlated with the probability of other males disturbing the female. Territorial males usually adopt the first of these strategies, whereas non-territorial forms typically remain in tandem. Species that oviposit in leaves and stems of plants or woody material are typically quite selective in their choice of sites (a feature that may be correlated with their life history strategy) (see also Chapter 23, Section 3.2.1) and have elongate eggs. Often, the female climbs a considerable distance below the water surface before laying the eggs. Exophytic species that oviposit in ponds or swamps may simply release their eggs into the water, or stick them on or under a leaf or on mud. However, the eggs of stream- or river-dwelling species may be deposited above the water level or have hooks that catch on submerged objects.

Embryonic development is usually direct, the eggs hatching within 5-40 days; however, in some temperate species the eggs serve as the overwintering stage and undergo diapause. The first larval instar, known as the prolarva, does not feed and its sole purpose is to reach a suitable body of water. Immediately this is achieved (which may take from less than a minute up to several hours), the prolarva molts. Second-instar and older larvae are facultative predators, feeding on whatever animals of appropriate size are available. Detection of prey is achieved primitively through the use of both visual and contact sense organs. In advanced species the eyes become of primary importance. Odonate larvae are themselves preyed on by aquatic vertebrates and other aquatic insects, including larger members of the same order, though intraspecific cannibalism is very rare as a result of territorial behavior among similarly sized larvae and because age cohorts within a species tend to be spatially separated (e.g., by preferring perches of different diameters). Larvae of most Odonata inhabit permanent waters either still or flowing. Those of many species live in burrows in the substrate, whereas most others, especially Zygoptera, are generally found perched on detritus or aquatic plants where their color provides camouflage. When detected, these larvae can escape rapidly by either expelling water from the rectal cavity—a form of jet propulsion (Anisoptera)—or using rapid undulating movements of the abdomen and caudal lamellae (Zygoptera). A relatively few species have colonized temporary bodies of

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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