This section describes insect fauna found in Pakistan, the major threats to insect Biodiversity, and measures that have been taken or are proposed for the conservation of insect Biodiversity
6.1 Insect Species in Pakistan
By far the majority of invertebrates in the terrestrial environment are insects. More than 2000 species have been recorded in Pakistan. A few species or groups of insects may occur in extremely large numbers and the biomass of invertebrates in a forest or plateau may be greater than the vertebrate biomass in the same environment. Pakistan has representatives of 13 insect orders.
The orders of Protura, Thysanura and Diplura comprise a small numbers of species that live in the soil or in kitchens or food stores. More than 150 of such species are known to exist in Pakistan.
Grasshoppers and crickets (Orthoptera) form an order having 152 species recorded from Pakistan. Most members of the grasshopper family, Acrididae, live on vegetable matter, but some of the bush cricket families, Tettigoniidae, also eat other insects. Some are large beautiful insects, which can also attract attention via their song.
Earwigs (Dermoptera) form an insect order with many species in Pakistan. These live on the ground where they eat small insects and vegetation. They are most commonly found in dirty kitchens, sewage pipes, food stores, etc.
Dust lice or book lice (Psocoptera) comprise an order of insignificant insects in Pakistan. There are two recorded species from Pakistan. They live beneath the bark of trees and feed on pollen and fungus myceli. A few species live in buildings and cause damage to books and Natural History collections.
Thrips (Thysanoptera) are very small slender insects with two pairs of thread-shaped wings with broad fringes. These live on plants, especially the flowers, ten species of which have been recorded in Pakistan. There are more than 159 species of bugs (Hemiptera) recorded in Pakistan. Lacewings and alderflies (Nemoptera) are two species recorded from Pakistan.
Other insect species recorded in Pakistan include:
Many species of scorpion flies (Mecoptera)
25 species of fleas (Siphonaptera)
315 species of butterfly (Lepidoptera) and
Species of bees, wasps and ants (Hymenoptera)
Other Arthropods found in Pakistan include:
Species of millipedes (Diplopoda)
Species of centipedes (Chilopoda)
84 species of arachnids (Arachinoidea)
225 recorded species of mollusca and 75 of nematodes.
Entomology is taught as a major subject in three agricultural universities: the University of Agriculture, Faisalabad; Sindh Agricultural University, Tando Jam, the University of Agriculture, Peshawar. Entomology’s major application is in the plant protection and community health sectors. Although this subject is of major economic importance for enhancing agricultural productivity, it has not been given the importance it deserves. There are a number of agricultural research stations in Pakistan, but entomologists have inadequate opportunities for advanced research and development in their field. Therefore, the present level of information on insect Biodiversity in Pakistan is very low. Integrated Pest Management (IPM) technologies that ensure reduction in the use of insecticides are applied on a very limited scale.
6.2 Use of Pesticides and Threats to Biodiversity
Since the early 1950s, with the discovery of the insecticide properties of DDT, insecticides have been used excessively for pest control. During this period, due to the spectacular success of chemical control, other control techniques were almost completely ignored. The indiscriminate use of insecticides has adversely affected Biodiversity by killing or eliminating animal species. However, the development of resistance in pests against insecticides; the resurgence of secondary pests; pollution of the environment; and presence of pesticide residues in the food chain; have stimulated renewed interest in alternative methods of pest control. Consequently, the interest in Integrated Pest Management (IPM) has developed.
More than two hundred pesticides including insecticides, acaricides, weedicides, nematicides, rodenticides, etc. are registered in Pakistan. Insecticides that have not been registered are also being imported under generic names. These are creating resistance in insect pests, causing serious environmental problems and posing a serious threat to Biodiversity.
At present, pesticides worth more than Rs.13 billion are imported into Pakistan annually. Most of these pesticides are non-selective toxic chemicals. Ecological and agricultural sustainability has become an essential consideration in Pakistan’s agriculture. The indiscriminate use of pesticides has been responsible for a number of problems such as environmental pollution, resistance in pests, and the upsurge of secondary pests due to the elimination of natural enemies.
6.3 IPM Projects in Pakistan
In Pakistan, foreign donor agencies including the World Bank, the Asian Development Bank (ADB), the Food and Agriculture Organisation (FAO) of the United Nations and the Swiss Development Co-operation mostly sponsor Integrated Pest Management (IPM) projects. The major on-going projects are:
Integrated pest management of sugar pests in Sindh
Integrated pest management of cotton pests in south Punjab
Integrated pest management of cotton pests with emphasis on the white fly in Multan Civil Division, Punjab
The Government of Pakistan makes minor contributions for the introduction, research and implementation of IPM projects. The Biodiversity of agro-ecosystems is lower in comparison to less disturbed ecosystems. The use of insecticides further adversely affects Biodiversity by reducing the number and populations of insects, especially those of natural enemies. When pesticides are used indiscriminately natural enemies are the first to be eliminated, resulting in an upsurge of secondary pests disturbing the Biodiversity of the agro-ecosystem.
Of the various methods of pest control, Integrated Pest Management is the best for the conservation of Biodiversity. IPM programmes for a number of crops such as sugarcane, mango, apple and cotton have been developed in Pakistan. The biological control components of IPM are introduction, conservation, redistribution and augmentation.
In introduction and redistribution, useful and beneficial species are transferred from one area to another. If they become established, they permanently add to the Biodiversity of the agro-ecosystem. They do not eliminate the pest species but bring their populations to sub-economic levels thus enriching the Biodiversity of the ecosystem. Table 6.1 gives an account of successes achieved in Pakistan by elimination or minimisation of pesticide use and thereby directly contributing to Biodiversity conservation. A number of species have been successfully introduced and redistributed in Pakistan (Table 6.2 and Table 6.3).
In conservation, desirable species (mostly of natural enemies) are protected or encouraged by the judicious use of insecticides and cultural practices or by providing shelter to natural enemies. Therefore, the populations of natural enemies are saved from destruction or elimination. This helps in improving Biodiversity. The natural enemies of the pests of mango, sugarcane and cotton have been conserved for pest control in IPM technologies.
In augmentation, populations of natural enemies are increased by the release of natural enemies at the proper time. This is based on detailed studies on the biology and ecology of the pests and their natural enemies. The addition of useful species at a certain time of the season not only enhances Biodiversity but also provides cheap and safe control of the pests for which otherwise poisonous insecticides would have been used.
In Pakistan, very little effort has been made to study the Biodiversity of agro-ecosystems. The challenge is to conserve or improve it before it is destroyed. Studies on this important aspect of agro-ecosystems should receive priority
Table 6.1: Successes in Biological Control and Integrated Pest Management in Pakistan