Hdh

708 Studies revealed, however, that the species oviposit in different microhabitats. M. immunis prefers to oviposit in the axils of dwarf side shoots, whereas M. unipunctatus selects girdle scars and leaf scars. The congeneric flea beetles, Phyllotreta cruciferae and P. striolata, are concentrated on different parts of their food plant, Brassica oleracea (cabbage and relatives). The former species shows a preference for sunny locations and occurs largely on the upper surface of top and middle leaves. P. striolata is concentrated on the underside of leaves, especially those near the base of the plant.

Diurnal segregation is shown by two species of Andrena, A. rozeni and A. chylismiae, solitary bees that forage on evening primrose (Oenothera clavaeformis) whose flowers remain in bloom for less than a day. Flowers open in late afternoon and are visited by A. rozeni between about 1600 and 1900 hours. A. chylismiae is an early morning forager and visits flowers between 0500 and 0800 hours, that is, just before they wilt.

Clear-cut seasonal segregation is shown by the damselflies studied by Sawchyn and Gillott (1974a,b, 1975), who were able to arrange the damselflies into three types according to their seasonal biology. Type A species, whichincludes Coenagrion resolutum, Enallagma boreale, and other Coenagrionidae, overwinter in diapause as well-developed larvae and emerge highly synchronously between the last week of May and mid-June. Sexual maturation takes about 1 week and the oviposition period extends to the end of July. Females lay eggs in the submerged parts of floating plants. Embryogenesis is direct and requires less than 3 weeks; half-grown larvae may be collected before the end of July and mature larvae by mid-September. Included in Type B are three species of Lestes: L. unguiculatus, L. disjunctus, and L. dryas, which overwinter in diapause as well developed embryos. Eggs hatch synchronously during early May, but the very young larvae are not preyed on by the larger larvae of Type A species either because they are too small, that is, outside the range of prey size, or because the Type A larvae have ceased to feed in preparation for the final molt. Type B larvae develop rapidly, and synchronized adult emergence begins in early July and is completed within 2 weeks. Adult maturation requires 16-18 days, and females oviposit in green emergent stems of Scirpus (bulrush), which may relate to the requirement of water for embryogenesis. Adults are not normally seen after the end of August, though in mild years they may survive into October. In Type C is included one species, Lestes congener, which is characterized by the lateness of its seasonal chronology. L. congener overwinters in diapause at an early (preblastokinetic) stage of embryogenesis. Embryonic development continues in the spring after the eggs are wetted and hatching occurs at the end of May. However, the young larvae are too small to serve as prey for the Type B species. Larval development is rapid in L. congener so that synchronized emergence begins in late July and continues for about 3 weeks. The much larger larvae of L. congener generally do not eat larvae of Type A species.Sexual maturation in L. congener takes about 3 weeks. Oviposition begins in mid-August and copulating adults may be seen until early October. Female L. congener oviposit only in dry stems of Scirpus, a feature associated with the lack of prediapause embryonic development observed in this species.

Thus, the occurrence of seasonal segregation between types and of microhabitat segregation (e.g., deep versus shallow water for larvae, and oviposition in floating vegetation, or emergent green or dry stems in adults) both between and within types, enables a number of species of Zygoptera to coexist and make use of the rich food supply (in the form of Daphnia, Diaptomus, and dipteran larvae) which is found in prairie ponds.

Dietary differences also enable closely related species to coexist. For example, larvae of the caddisflies Pycnopsyche gentilis and P. luculenta coexist in woodland streams in

Quebec because the former prefers fallen leaves, whereas P luculenta feeds on submerged twigs or, if these are not available, on detritus or well-rotted leaves (MacKay and Kalff, 1973).

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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