THE POLLINATION is a pivotal process in almost all productive ecosystems but pollination has been generally overlooked until very recently. The vital roles of pollinators are no less important in remote wilderness of the Arctic and deserts than in highly managed farming system. There are roughly 200,000 varieties of animal pollinators in the wild, most of which are insects. Entomophily, pollination by insects, often occurs on plants that have developed colored petals and a strong scent to attract insects such as, bees, wasps and occasionally ants (Hymenoptera), beetles (Coleoptera), moths and butterflies (Lepidoptera), and flies (Diptera).
Insect pollinators play an important role in crop production and also increase the yield of fruit orchards (Apple, Almond, Pear, Apricot, Plum, all type Citrus fruits, Cherry and Strawberry), vegetables (Cucumbers, green house and hydroponic Tomato, Squash and Melons) and field crops (Sunflower, rapeseed, Legumes and Alfalfa). In forests and other natural areas pollinators assist in the production of fruits and seeds that are essential to the diets of wildlife such as birds, large and small mammals. The native pollinators can improve yield of agricultural crops, such as apples, almonds or rapeseed by about twenty percent. Pollinators also act as bioindicators organism that their presence, abundance and activities reveal the state of ecosystem in which they are found.
More area is being brought under cultivation especially apple and cherry orchards which leading to more amount of pesticide being applied. The indiscriminate use of pesticides in fruit orchards, vegetables and crop fields has lead to may problems including environmental hazards, reduced populations of pollinators, elimination of natural predators and parasitoids, increased resistance in pests, pesticides residue, change of status from minor pests to major pests and hence increased frequency of pesticides application. A study was carried in Ziarat district to asses the effect of pesticides applications in agricultural field on the insect pollinators.
Maximum diversity and population of pollinators was observed in the natural ecosystem where natural Juniper forest and Russian sage were common plants. It was also observed pollinators diversity and population was slightly affected by the one or two pesticides application early in the season. However the biodiversity of pollinators was severely affected by 4-5 pesticides application on apple orchid
The common pesticides used by the farmers in Ziarat valley were Pyridaben (insecticide and acaricide), Emamectin (insecticide), Chlorpyrifos (insecticide), Propargit (acaricide), Profenofos + Cypermethrin (insecticide with acaricidal activities). These pesticides were applied against codling moth at early stage (in May) and mite at latter stage (in July and August). Most of these pesticides belong to Organophosphorous group of pesticide and are persistent. These pesticides were recommended by the sellers instead of technical staff of Agriculture or Plant Protection departments.
The farmers followed a calendar sprays schedule i.e. a pesticide application after every fifteen days without proper pest scouting or estimating the pests or predators and parasitoids populations. The farmers do not follow any safety precautions and dose calibration methods. At some places apple fruits were being picked on the next day of pesticide application. Apparently the farmers were not aware of hazards or ill effects of pesticide. Plant Protection department (Provisional or Federal) may be asked for the training of local agricultural staff and farming community, and create awareness.
The protection of native pollinators is very important at this stage and different measure could be planned
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Integrated approach should be adopted to control the pest. If pesticide has to be applied it should be recommended by the plant protection staff after proper pest scouting. Alternative control measure should be searched like biological. -
Hedge, field margin and increasing unsprayed buffer zones around crops is important to the success of any new strategy to prevent the harmful impact of pesticides. -
Home gardening should be encouraged. -
A further study should be initiated to list all the pollinators, especially at flowering stage of Apple, Cherry, Peach and other fruit in the area.
The cultivation of Walnut, as an alternative to apple or cherry should be encouraged as it has low water and no insecticide requirement; and also most earn same amount of profit.
The author is Curator, Zoological Sciences Division at Pakistan Museum of Natural History, Islamabad