Intraspecific Interactions

The nature and number of interactions among members of the same species will depend on the density of the population. These interactions may be either beneficial or harmful. It follows that there will be an optimal range of density for a given population, within which the net effect of these interactions will be most beneficial. Outside this range of density, that is, when there is underpopulation or overpopulation (crowding), the net result of these interactions will be less than optimal for perpetuation of the species. Animals have evolved various regulatory mechanisms that serve either to maintain this optimal density or to alter the existing density so as to bring it within the optimal range. In the discussion that follows it will be seen how these mechanisms operate in some insects.

4.1.1. Underpopulation

Probably the most obvious detrimental effect of underpopulation is the increased difficulty of locating a mate for breeding purposes. For most species, mate location requires an active search on the part of the members of one sex, which under conditions of underpop-ulation might present a special problem for weakly flying insects. To alleviate this, many species have evolved highly refined mechanisms (e.g., production of pheromones, sounds, or light) that facilitate aggregation or location of individuals of the opposite sex (Chapter 19, Section 4.1). The relatively slight chance of finding a mate is offset to some extent by the fact that one mating may suffice for fertilization of all eggs a female may produce; that is, sperm may remain viable for a considerable period, and a female may produce a large number of eggs.

On some occasions the effect of non-specific predators is much greater when prey density is lower than normal because the chance of an individual prey organism being eaten is increased. For example, in the period 1935-1940 the population density of the Australian plague grasshopper, Austroicetes cruciata, was high. However, drought conditions in the

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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