Insects: beneficial pollination

Planted hedges hedges provide a biotope and refuge for plants and animals which have often already become rare, as well as for natural enemies of pests (e.g. birds, hedgehogs, beneficial insect species), pollinators (e.g. bees) and complex communities which enhance the ecological balance. 

Providing for beneficial insects that pollinate as they travel around the yard, fly from one yard to the next, or feed on pests such as aphids (one hoverfly larva can eat around 1,000 aphids in its lifetime) is one of the most helpful ways to support wildlife. Flowers, for example, provide nectar and pollen, which insects such as butterflies, bees, hoverflies, and lacewings need. Both native and non-native plants can provide this, but they must have flower structures that allow the insects to get at the nectar and pollen. 

The favorable ecobiological profile of bifenazate is remarkable [4, 13-15]. The compound does not affect beneficial insects, neither pollinating insects nor beneficial predatory mites nor wasps (Table 30.2.5). 

Compound (V) is used as an insecticide and is marketed as a 50 per cent solution under the name of hanane, which also contains 5 per cent of O.M.P.A. Hanane properly placed at the roots of cocoa trees kills mealy-bugs in the crown of the tree without harming beneficial insects such as ants which effect pollination. Five hundred trees infested with mealy-bugs were treated 2 10 per cent of the trees, chosen at random, were cut down before treatment and after treatment, and the number of mealy-bugs counted under a binocular microscope. After 6 weeks only thirty-five mealy-bugs were present on the treated trees as opposed to 42,971 counted before treatment in the untreated portion, a reduction of 99-9 per cent. It is well known that several species of mealy-bug, especially Pseudococcus ujalensis, transmit strains of swollen shoot virus, which kill the cocoa tree in 2-4 years. Thus the spread of the disease can be effectively controlled by this systemic insecticide (see also p. 171). 

Most species of insects are beneficial or even essential to agriculture. Honeybees, for example, are responsible for the pollination of 10 billion worth of produce in the United States. Countless other species take part in nutrient recycling and help maintain soil quality. A small minority of insect species, however, has continually threatened our capacity to grow, harvest, and store crops, and it is against these species that insecticides are used. The most widely used insecticides are chlorinated hydrocarbons, organophosphorus compounds, and carbamates. 

The pest insects that eat our treasured ornamentals and rob a share of the vegetable harvest are only a tiny fraction of the total insect population around us. The overwhelming majority of insects are harmless members of the natural community. Many are directly beneficial in their role as crop pollinators, predators on pests, and decomposers of plant material, d hey can be as common as houseflies, distributed globally, or as rare as the flea that lives on the skin of certain sea mammals or the midge that lives in the tiny pool of water in a pitcher plant. 

As gardeners, we are most likely to notice the pest insects in our yards and gardens. However, entomologists estimate that more than 90 percent of all insects are beneficial. Wild and domestic bees and also some flies and moths pollinate crops this is essential for the development of many fruits, vegetables, and crops grown for seed. Honeybees are also farmed to provide honey, and silkworms are farmed to yield silk from their cocoons for fine clothing. 

The majority of resistant species (56.1%) are of agricultural importance, but a substantial proportion (39.3%) represents insects of medical importance, especially mosquitoes and flies. Only 4.6% are beneficial species (predators, parasites, or pollinators) (Table III). For a detailed index of cases of resistance see Georghiou, G. P. Lagunes, A., The Occurrence af Resistance to Pesticides in Arthropods, 2nd d., F.A.O. Rome, in press. 

Rohm and Haas has devised diacylhydrazine agonists of ecdysone (11.44) for caterpillar control that induce a premature lethal molt in a few hours.176 It does not harm beneficial insects, such as bees, ladybugs, and wasps. However, it could be toxic to other butterflies and moths, at least some of which are natural pollinators. 

Donovan, B.J. and Macfarlane, R.P. (1984). Bees and pollination. In New Zealand Pests and Beneficial Insects (Scott, R.R., Ed.). Lincoln University College of Agriculture, New Zealand, pp. 247-270. 

In contrast to such strong insecticidal activity against lepidopterous insects, pyridalyl showed little insecticidal activity against species of Hemiptera, Coleop-tera and Orthoptera. Such selectivity of the compound is reasonably regarded as a preferable characteristic for uses in I PM programs, because some natural enemy insects are included in those families. In fact, pyridalyl showed minimal impacts on various beneficial arthropods such as parasitic wasps, predatory insects and mite and pollinators (Table 30.3.5) [1, 6, 7]. 

An ideal insecticide should not only be selectively toxic to the target insect pest but also should be non-toxic towards non-target beneficial insects at pesticidal doses. Beneficial insects fall under three categories, viz, (a) pollinators / productive insects that yield products of commercial importance. 

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