Citrus stands first in area and production among the worlds tree fruits. In Pakistan also, citrus fruits are the most important fruit crops grown on the area of 160,000 hectares with production of 1.5 MMT annually. Citrus fruit is grown in all four provinces of Pakistan but Punjab produces over 95 per cent of the crop because of its greater population, favourable growing conditions and adequate water. So to attain maximum output we need to minimize these losses to achieve maximum yield and farmers also get more income for their efforts. Pakistan has very fertile and variety of soil. It has variation in its soil and climatic conditions, which is very favourable for the production of fruits, vegetables, flowers and other crops. Mostly high valued fruits, vegetables and crops are produced in our country. Citrus is the most important in all other fruits for its production and trade.
Citrus is the biggest group which is commonly produced in our country. This fruit have the high potential in exporting in foreign countries as well as full fill the needs of the country. Mostly a few insect pests attack on harvested fresh fruits of citrus. In common damage due to larvae of insect e.g. fruit fly. The attack of insects on citrus fruits usually occurs before harvesting. Attack of insect pest in post-harvest fruit of citrus is a very difficult problem specially, at that place where fruits of citrus are needed to be stored. In general 35 per cent of the produce is lost during pre- and post-harvest stages due to poor disease management, weather conditions, harvesting delays, poor harvesting practices, poor road conditions, lack of cold storage facilities and insect pest attacks specially fruit flies. Fruit flies are present in most countries and attack many types of fruits, as well as fruiting vegetables, ornamental flowers and some nuts. Feeding by fruit fly larvae (maggots) damages the fruit internally, causing it to ripen prematurely and rot. Up to 100 per cent of fruit may be damaged by fruit flies when infestations remain uncontrolled.
The presence of fruit fly can also result in loss of valuable interstate and export markets. Some activity will continue in warmer periods during winter months. Adults of both species of the fly become active in spring and start laying eggs in mature fruit. For both species of the fly the preferred hosts are stone fruit that can support and buildup their populations before citrus fruits are available as cites for egg laying. The adults can live for a few months and lay hundreds of eggs, a few millimeters deep inside the fruit. Fruit fly may lay up to 1,000 eggs during her life. Eggs hatch in a few days and the larvae eat through the fruit, growing to about 9mm long when mature. Infested fruit often ripe prematurely and drop on the ground. Fruit flies are serious agriculture hazard throughout the world and represent a threat to successful establishment of horticulture industry and trade. The existence of fruit fly also means that crops that reach the market are not eligible for export due to quarantine regulations. Strategies for the control of fruit flies should posses the following components: sustainable, suppression and environmental friendly.
The management approaches may include physical control, cultural control, biological control, the sterile insect technique (SIT), male annihilation technique (MAT), protein bait technology and insecticides cover spray as there is no single, one-answer solution to the fruit fly problem.
The following methods for fruit fly management are available to organic producers and should be applied to home garden trees as well as commercial orchards.
EARLY HARVEST: As the season progresses, fruit fly populations, attractiveness of fruit to fruit flies and the risk of damage increase. Tall trees are more likely to carry un-harvested fruits that can act as infestation sites for fruit flies.
TRAPPING: Traps are generally considered useful for monitoring fruit fly populations rather than controlling them. Recent overseas research, however, indicates that high densities of traps can remove enough fruit flies to significantly reduce the level of fruit damage. Traps attract fruit flies by using pheromones, food scents or visual cues. Pheromone traps contain a sex pheromone that attracts male flies. Depending on the trap type, the flies drown in liquid bait, get caught on a sticky layer or are killed by a contact insecticide.
BIOLOGICAL CONTROL: Newly emerged flies need up to 24 hours for their wings to harden before they can fly, so are prone to predation on the soil surface by birds, ants, bugs and earwigs. Birds including domestic poultry may also contribute to the control of fruit fly larvae in fallen fruit and shallowly buried larvae and pupae. Cultivation would increase the exposure of larvae and pupae to these and other predators, but is not desirable where it would be needed right under the trees. Parasitic wasps and nematodes also attack various stages of fruit fly. While all of these natural enemies help to reduce fruit fly numbers, they are very unlikely to provide economic levels of control. The destruction of fallen, damaged, over-ripe and excess ripe fruits is strongly recommended to reduce resident populations of fruit flies. Crop residues such as fallen, over-ripe or damaged fruits may be destroyed by deep-burying.
So it is highly recommended that fruit orchard growers should adopt these methods and safe fruit fly for future development of horticulture industry for export.
The writers are associated with the Institute of Horticultural Sciences, University of Agricultural Faisalabad, Pakistan.