Man and insects
The ways in which insects affect man's welfare are many and varied. Those insects that are in some way harmful we refer to as(称……为) pests, but important as these are, they in fact make up only a small minority of insect species. Of the one million or so different species of insects that exist, only a few thousand qualify for pest status. In contrast, many insects are distinctly beneficial to man in that they act as natural enemies of harmful species, as pollinators of many cultivated plants, or as producers of valued materials such as honey and silk. The bulk of insect species, however, fall into neither of these categories of clearly harmful or beneficial, but nevertheless are extremely important as essential components of both natural and modified ecosystems. The main ways in which insect activities affect man's welfare are set out in Table 2.
Table 2. Insect activities in relation to man’s welfare
Value of activity relative to man | Type of activity | Effects |
HARMFUL | Pest of cultivated plants
Pest of farm animals
Pests of stored produce (principally human and animal foods)
Pests of timber and wood products. Pest of medical and public health importance.
Pests in households and industrial premises[[ˈprɛmɪsɪz]房屋]. | Reduction in yield and quality of produce. Transmission of plant disease. Discomfort. Reduction in vigour and growth rate. Lowered production (dairy stock). Damaged skins and hides (兽皮). Transmission of disease. Accelerated deterioration. Reduction in quality and nutritional value. Aesthetically（esˈθetikəli, 美学地，美地） offensive. Accelerated deterioration resulting eventually in structural failure. Discomfort. ill health. Reduction in vigour. Transmission of disease. Aesthetically offensive. Damaging to stored food and other produce, e.g, wool and woolen goods. Unhygienic[ʌnhaiˈdʒi:nik]. |
BENEFICIAL | Natural enemies of pest species (may include undesirable plants. e.g. Weeds, as well as pest insects) Pollinators of cultivated plants.
Producers of useful materials. | Suppression of pest or potential pest.
Provide essential pollination of many cultivated plants, especially many horticultural crops. Production particularly of honey and silk. |
NEUTRAL | Components of natural and modified ecosystems. | Important components of bio1ogical systems essential to man’s long-term welfare. |
*Note: it is the type of association of an insect with man that justifies the label pest rather than the species itself, e.g, honey bee are in the main highly beneficial but may be regarded as pests by growers of glasshouse cucumbers who do not want their plants pollinated as this results in deformed fruit.
