Predators beetles

Bark Beetle D. rufipennis Beetles/Predator Beetles/Competitor Ref. 

Biological and Natural Controls. Parasites and predators are effective in limiting the numbers of pest Insects and plant pathogens both in nature and for crops (35). This basic fact led to the development of biological controls. For example, the vedalia beetle, which was Introduced for control of cottony cushion scale on citrus in California, has provided continuous effective control of this pest for many decades. Worldwide only approximately 1% of the pests have been effectively controlled by Introduced biological control agents (43). 

What chemistry is used by bombardier beetles to repel predators ... 

Many grasses are known to act as reservoirs and sources of primary C. purpurea inoculum (Hoffmann and Schmutterer, 1983 Agrios, 1997). Since beetle banks and non-crop field margins are commonly used in organic farming to increase biodiversity, it is possible that these areas may also become sources of Claviceps inoculum. The goal for farmers must be to achieve a balance between the benefits of on-farm biodiversity (e.g. improved habitat for pest predators) and the risk of increased infection by fungi such as Claviceps. 

Widespread use of mirex may lead to altered population structure in terrestrial systems, with resurgence or escalation of nontarget pests due to selective mirex-induced mortality of predators (NAS 1978). For example, populations of immature horn flies and rove beetles, two species of arthropods normally preyed upon by fire ants, were higher in mirex-treated areas than in control areas (Howard and Oliver 1978). Conversely, other species, such as crickets, ground beetles, and various species of oil-loving ants, were directly affected and populations were still depressed or eliminated 14 months posttreatment (NAS 1978), whereas fire ants recovered to higher than pretreatment levels, as judged by mound numbers and mound size (Summerlin et al. 1977). 

A detailed predator-prey analysis of the chemical relations between the carabid Pasimachus subsulcatus and the skink Eumeces inexpectus proved that the latter were repelled by constituents of the carabids secretions, indicating that the beetles are chemically protected from attacks by the lizards [85]. 

Several predation tests especially with spiders and blister beetles [121,313, 314], show that spiders exhibit a wide range of sensitivities to meloid beetles as prey. In the racoon Procyon lotor it was shown that they quickly form an aversion to blister beetle prey, which is induced by cantharidin [314]. 

When disturbed or molested, these insects release small droplets of hemo-lymph from the tibio-femoral joints of their legs, and it is now well established that the deterrency exhibited by many species of coccinellids towards potential predators results from the presence of repellent and bitter alkaloids in that fluid [ 12,13]. In ladybirds, this unpalatability is associated with a bright aposematic coloration and a characteristic smell due to 3-alkyl-2-methoxypyrazines [14, 15]. The beetles use these molecules not only to reinforce the visual alerting signal on an olfactory level, but also as aggregation pheromones [16]. 

To control pests Frogs, beetles, and other pest predators appreciate the cool, damp cover provided by green manure. Some pests can be confused by the presence of green manure planted between food crops. 

Winter digging can expose overwintering pests for predation by birds and ground beetles. However, don t go too far when tidying up the garden spare a thought for the beetles, centipedes, and toads that play a vital role in pest control. They need safe, undisturbed locations to thrive. 

Predation of bark beetles by woodpeckers in different forest communities... 

The catalysts are enzymes, most of which are proteins. Not only are they catalysts, bnt their catalytic powers are enormous they can increase the rate of a reaction by several orders of magnitnde. Indeed, in the absence of enzymes, life as we know it wonld not be possible. One remarkable example of the nse of the catalytic power of two enzymes in biology is the Bombardier beetle it uses the enormous catalytic power of the enzymes catalase and a peroxidase to deter predators (Box 3.1). 

The Bombardier beetle possesses, at the end of its abdomen, a combustion chamber that contains a hydroqui-none and hydrogen peroxide. When a predator approaches, the cells in the walls of the combustion chamber secrete two enzymes, catalase and peroxidase. Catalase causes decomposition of hydrogen peroxide to produce oxygen peroxidase catalyses the oxidation of the hydroquinone to produce a quinone. 

The beetle directs the end of its abdomen towards the predator which is sprayed with a hot quinone, which deters further interest in the beetle. 

For example, the lack of good alternatives pushed the U.S. Department of Agriculture in 1998 to recommend the use of methyl bromide to treat wood packaging materials from China. A voracious, nonnative insect pest had been found in such packaging materials in 14 states around the United States. The Asian beetle had no known U.S. predators and could cost the United States more than 41 billion in lost forest product, commercial fruit, maple syrup, nursery, and tourist industries. This beetle was an extremely serious insect, and methyl bromide was the only known effective insecticide. Heat treatment was also suggested, but it proved to be more difficult and expensive (Morse 1998). Therefore, methyl bromide as an insecticide was receiving a reprieve. 

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