Insects threats from

Pests and Insecticides. The most destmctive pests of the cotton plant are the boU weevil and the boUworm/budworm complex. They are serious threats to the cotton industry in countries around the world. The boU weevil migrated from Mexico around 1892 and spread over the entire cotton belt within 30 years. The domestic cotton crop lost to the weevil is worth 200 million a year. In addition, about 75 million a year is spent for pesticides to control this destmctive pest (8). Unfortunately, some insecticides used to control the weevil kill many beneficial insects. Among the undesired casualties are insects that help to control the boUworm and the tobacco budworm, pests that cause another 200 million loss in cotton. 

Water birds have not been shown to be directly affected by acidification. However, the prey of waterbirds may be of concern as these lower food-chain organisms may have elevated levels of toxic metals related to acidification of their habitat. Moreover, most water birds rely on some component of the aquatic food-chain for their high protein diet. Invertebrates that normally supply caJcium to egg-laying birds or their growing chicks are among the first to disappear as lakes acidify. As these food sources are reduced or eliminated due to acidification, bird habitat is reduced and reproductive rate of the birds is affected. The Common Loon is able to raise fewer chicks, or none at all, on acidic lakes where fish populations are reduced 37 and 5S). However, in some isolated cases, food supplies can be increased when competitive species are eliminated (e.g.. Common Goldeneye ducks can better exploit insects as food when competition from fish is eliminated). The collective influences of acidification are difficult to quantify on a specific area basis but for species that rely on a healthy aquatic ecosystem to breed, acidification remains a continuing threat in thousands of lakes across eastern North America 14). 

The evolution of movement and behaviour also opened up a huge range of threats and opportunities to the land plants. It is not practical to consider all the range of species interactions in this chapter therefore, examples will be drawn from the interaction of plants and insects. 

The cold-hardy beetle Dendroides canadensis. A very different scenario from those presented above can be sketched for a freeze-avoiding insect from the temperate zone, where the threat of freezing, while only seasonal, is much more severe than that faced by fishes from high latitudes. One of the best-studied freeze-avoiding insects is the beetle Dendroides canadensis (Duman, 2001 Duman et al., 1993). Compared to freeze-avoiding fishes, D. canadensis mounts a much more extensive freeze-avoidance response and... 

Many insects, including aphids, leafhop-pers, and whiteflies, carry viral diseases from infected to healthy plants. Mites, nematodes, and fungi also transmit viral diseases, as do parasitic plants. Any of these organisms cause plant damage by themselves, but they pose an even greater threat when carrying a virus. Plants tolerate a certain amount of aphid feeding, for example, with no apparent harm. However, if those aphids inject a virus into one of your plants, the plant becomes permanently diseased. 

The insect problem is insidious, Grain may become infested in (he field and the pest carried into a clean store (Giles and Ashman, 1971). Small amounts of infested grain from the previous year s crop, lodged in crevices, can effect a rapid infestation of the new crop. Insects thrive on a wide range of conditions (Howe, 1965) and constitute a threat in most parts of the world. 

My threat is being bitten by a poisonous insect or even spider. I will assume that a single bite is debilitating, or even deadly, and should be avoided wherever possible. This could be either the bite from the lethal Sydney funnel-web spider or from a brown recluse spider or a sting from a common bumblebee when the individual is allergic to it. Unlike some of the chemical risks discussed earlier, where the actual threat to humans is debatable, there is no doubt that venomous pests present a serious health hazard to certain individuals. 

Also Chinese documents from the Shang Dynasty (1523-1027 BC) reveal the threats posed by insects. Therefore, attempts were made to battle, for example, the migratory locust Locusta migratoria maniiensis with fire. In Greek and Roman writings, there are reports of plant damage, preventive measures, and pest control possibilities. For instance, Phny the Elder describes the use of ashes, crushed cypress leaves and diluted urine as insect repellents. 

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