Population controlling agents

Organo-phosphorus compounds and fly control. Certain organo-phosphorus compounds have been used as fly-controlling agents, where fly populations have become resistant to chlorinated hydrocarbons such as D.D.T.2 The compounds are applied in the form of sugar baits which attract the flies and so increase the effectiveness of the poisons. 

Many animals in the garden feed on pests. Some, like lady beetles, are more obvious than others, and get most of the thanks. Some we like for aesthetic or sentimental reasons and readily inflate their importance in the pest control stakes, such as toads. But many insignificant creatures work unnoticed, keeping pest populations below threshold levels. The animals pictured and described overleaf are effective pest control agents in the garden. 

If microbes cause off-flavors, it might seem logical that the destruction of microbial populations with chemical control agents (biocides) would prevent the occurrence of off-flavor metabolites. Unfortunately, nonselective biocides can initiate a series of events that may be ultimately more problematic than off-flavors (49, 58, 59). 

Protozoa, again, are found in waste treatment processes where these generally motile forms graze on bacterial populations. The most important and interesting application concerns the use of these organisms as biological control agents. 

Some groups of entomopathogenic viruses are capable of causing severe epizootic diseases in insect populations. We consider these viruses excellent natural pest control agents if the host insects are destructive species. Natural epizootics of viral diseases are known to have terminated outbreaks of major forest pests, such as the nun moth in Europe and the Douglas-fir tussock moth in the United States. 

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