754 cultivation practices to improve the microclimate, increasing ecosystem diversity, and using insecticides that are non-persistent or benign to the control agent).

As in the history of chemical control, several early successes with biological control led some scientists to believe that this method might be the one to solve the world's pest problems. However, with an increase in knowledge of ecology, specifically predator-prey and host-parasite relationships, and in the length of the list of failures in biological control projects, this view has been markedly tempered. It is now realized that for some pest species, biological control will not work, and that for some others, biological control has been or will be a highly effective method. Between these two extremes, and forming the majority of pests, are those for which biological control will be an effective tool when used in conjunction with other methods of pest control, that is, as a component of integrated pest management. For many years, biological control was a "poor relation" to chemical control, even though several outstanding successes of biological control were recorded before the advent of synthetic insecticides. However, with the increasing appreciation of the problems caused by synthetic insecticides, biological control began to receive a greater share of the attention of applied entomologists, industrial concerns, and government agencies.

The importance of naturally occurring biological control must be emphasized. DeBach and Rosen (1991, p. 102) suggested that "upon it rests our entire ability to successfully grow crops, because without it, the potential pests would overwhelm us." These authors estimated that 99% or more of potential pests are under natural control. However, by its very effect, namely, the prevention of species from becoming sufficiently abundant to be designated as pests, it is easily overlooked. Only by very careful study of ecosystems in equilibrium or by disturbance of ecosystems can its value be appreciated. Two common methods of ecosystem disruption are (1) transfer of a species from its original habitat where it is not a pest to a new habitat where, in the absence of natural enemies, it flourishes and becomes a pest, and (2) indiscriminate use of broad-spectrum insecticides that decimate both pest and natural enemy populations. As noted above, the pest normally recovers more rapidly than its predators or parasitoids and becomes even more destructive than before. Examples ofboth forms of disruption were given in Section 2.3. DeBach and Rosen (1991) list more than 20 cases of naturally occurring control of homopteran pests (mostly scale insects), and further examples involving pest insects of other orders are given in the papers by Hagen et al., Rabb, and MacPhee and MacLellan, in Huffaker (1971).

Augmentative biological control was carried out in China at least 2300 years ago. The Chinese collected from the wild (or bought) colonies of the tree-nesting ant Oecophylla smaragdina which they placed in their citrus trees to control caterpillars and wood-boring beetles. In addition, they placed bamboo runways from tree to tree to facilitate the ants' movements. Apparently, this practice is still used in Burma and perhaps parts of China (DeBach and Rosen, 1991). Augmentative biological control in more recent times came to the forefront as a means of controlling pests that had become resistant to chemical insecticides (van Lenteren, 2000, 2003). Its main uses today are for control in field crops attacked by only a few pest species and in greenhouses where there is a spectrum of pests that are controlled by a variety of natural enemies (Kogan et al. and Parrella et al., respectively, in Bellows and Fisher, 1999). Two strategies are used in this form of control. Inundative-release is where the biocontrol agents are released in large numbers to obtain rapid control (i.e., as a "living" insecticide), in systems where viable populations of the agents cannot be maintained and only one generation of the pest occurs. Seasonal inoculation, the release of several control agents simultaneously on a seasonal basis, is used where several pest generations

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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