Control of Fruit Fly by Different Techniques
Fruits and vegetables production are the main source of income for farmers. There are many factors which ae responsible for production losses, environmental factors, diseases and also included different types of insect pests. Some pests damage the crops, fruits and vegetables severely. Fruit fly is the major pest of fruits. Fruit fly damage the horticultural crops by oviposition the surface of fruit or vegetable. After this egg are hatched and larvae feed’s from inside the fruits. It causes a serious economic loss to the farmer’s interest. According to an expectations 10% pests of horticultural crops are found in tropical and subtropical regions. Now these days major problem is control of these insect pests.
There are eight different species of fruit fly these species are categories on the basis of their attack. Peach fruit fly, natal fruit fly and medfly attacks on fruit trees including peach, mango, guava etc. Ber fly attacks on jujube and Masson. Tomato fly attacks tomatoes, while melon fly attacks on cucurbits.
Mode of damage:
Control of fruit flies is very difficult task due to their mode of damage. They puncture the fruit skin and lay eggs inside the fruit by their ovipositor. The small punctured like hole is cured very soon, nobody can judge the damaged spot visually.
Eggs inside the fruit hatched with the passage of time, maggots feed on fruit pulp securely. The outer surface of fruit is blushing while inside is spoiled by the maggots.
There are several practices to control fruit fly.
- Cultural techniques
Most important step for the control of fruit fly is its identification. Because there are many species of fruit flies which attack the plants on the same time and same parts of the plant. Every damage is not done by the pests, it might be seasonal or environmental. So, before using any pesticide or bait treatment, must be consulted with the nursery manager or the professional. This is the plus point for both the control and to the farmer economically.
- Sterilization of crop
The first and most important measure for the controlling of fruit fly, is the proper management of fallen fruits. The fallen or over ripen fruits should be properly buried in the soil up to 50cm deep in the soil to control the pest population and to ensure the cleanliness. Because, research shows that the remaining fallen fruits on the ground play a major role in further reproduction. So, the rotten fruits should not be remained open. They should be packed in plastic bags, exposed to the sun. So that the hide organisms are killed.
- Early Harvesting of crop
To avoid fruit fly attack, early harvesting is done. Because the fruit fly attacks on the fully ripened fruit or vegetable, not on the green mature fruit. So, harvesting of mango and banana in their young stage, restricts the fruit fly attack. Banana, orange and mango crops are exported on large scale. So, their harvesting should be done early.
- Variety selection
Attack of fruit fly is maximum in the late summer and autumn. So the growers should grow those varieties which are ripened before the attacking season.
The trees which are properly pruned and have a reasonable height, have less chances to be attacked. Because they are well managed and are exposed to be sprayed and treated well. They are easy to be examined either they have attack or not. The trees whom fruit and shoots are touching the ground, have more chance of attack.
Infested fruits that are fallen down, are collected and crushed by the garden tool or rolled on by the PVC pipe in the sun. Maggots cannot survive in the crushed or rolled frits, exposed them to the sun.
- Simple Control
Take a small jar, pour apple vinegar and some dishwashing liquid in the jar. Cover jar’s mouth with a plastic wrapper. Make holes in the wrapper. Fruit flies are attracted towards the jar and fall inside. As dishwashing bar alters the vinegar surface tension, so the fly fall down rather than staying over the surface.
- Same Varieties
Avoid growing the different varieties of fruit or crop in the same field. Because the fruit fly normally grows up on late ripening varieties. So the varieties which are ripened early before the breeding season of flies, should be grown.
- Weeds Growing
Weeds should be carefully grown around the fruit tree. Because weeds act as an alternative host for fruit fly, avoid damaging of fruit that falls down, and make it easy to see the fallen fruit. So, weeds can play a vital role in controlling fruit fly.
- Biological Techniques
- National Fruit Fly Control Program
In this method, bait is used to attract both the male and female. While the MAT (male annihilation technique) blocks attracts only males. Bait is used in selected areas to lessen the fruit fly population. As it is eco-friendly, so it has less effects on other organisms. The aim of this program is to boost up the fruit production and lessen the fruit flies in the growing areas near houses.
Bait is given to the farmers by Govt. in a small amount according to their fields. In the field, separation of the rotten fruits affects more than sprays against fruit flies. The farmer should not be relaxed after spray or bait treatment, he should visit the trees on regular basis.
- Sterile Technique
This is a technique of biological control. In which the bait is treated on the lower sides of the leaves, as they are the resting sites for fruit flies. Bait have dual action on the flies, mostly the flies are killed on ingestion the bait. The second action, attacks on the reproductive system of the flies. Males become sterile, if there is laying of eggs, the eggs would not be fertilize. So, the population is controlled.
Most prominent predators of fruit fly maggots are;
Ants Solenopsis spp. And phiedole spp. (Hymenoptera; Formicidae). Some species of rove beetle; Bilonnchus (Coleoptera), Carabidae (Coleoptera). Spider and bugs are also predators. These predators have vast range of attack on many other species, so when these predators are present in the garden, try to save their populations.
- Food attractants & pheromones
Some kinds of attractants, parapheromones and pheromones are being used to catch the fruit flies from field. Baits are also used but they do not attract the pests as much pheromones can. Baits are used 10m far from the source.
Pheromones, such as trimedlure, cueleure and methyl eugenole are used as traps to capture the Ceratitis, Dacus and Bactrocera species of fruit fly. Soya bean, corn and yeast based trap is called parapheromone trap, which is used to catch the aimed species, not any other.
- Natural enemies
P.humilis, Fopius arisanus and Diachasmimorpha are prominent parasitoids of fruit fly which is very effective and easy to rare. Psyttalia lounsburyi is also a parasitoid.
The premature fruit should be bagged over to avoid fruit fly attack. Cloth should be free from holes.
Yellow panel, adhesive sheet, open bottom dry, plastic Mcphail, champ trap, Jackson trap, Steiner trap and tephri trap are the biological methods which control fruit fly.
- Chemical techniques
- Male annihilation technique (MAT)
This is a technique used to control the peach fruit fly. This technique controls the male to least level.
- Fiber blocks
Fiber blocks of size (5x5x0.5cm) is saturated with the 10ml male sex attractant (methyl eugenole) with fenetrothin insecticide. Blocks are distributed at the rate of 1 block per acre with a distance of 65m.
- Bait spray application technique
This is a technique to control the specified species of fruit fly. In composition, in an insecticide a food attractant material is mixed with. Then it is sprayed. Percentage of attractant material varies species to specie. Mostly it is 10%.
Phloxine B is a toxic element eliminated after experiments, which kills the medfly and several other species. Spinosad has been improved chemically to control and attack only on fruit flies rather than the predators like honey bee, spider and ants.
Spraying method is somewhat specific, 100-150ml bait mixture is used. Here one should keep in mind that spray will not contact with fruits or vegetables. Spraying process is done row wise. One row is sprayed while adjacent two rows are left according to the infestation.
- Soil treatment
On detection of fruit fly maggots, chemicals (Diazinon, Fenthion) are directly applied to the host plants and soil. Maggots are killed, definitely the population would be controlled.
It is done 2-3 times, due to the controlled amount and reasonable use, there is no leaching of these chemicals.
- Mass trapping
This technique is used to control the adults. On traps there is female attractant, which works. These are given in packets i.e. 21 traps/acre. One treatment remains for 4 months long.
- Postharvest Techniques
- Warm water path
The fruit, especially mango which is to be exported, is thrown in a hot water path at 46-48oc for an hour. Due to this treatment the maggots or microorganisms inside the fruit, are killed and fruit is safe to health. This treatment is specially done for Bactrocera zonata.
- Hot water vaporing
When the pulp of fruit reaches to 46.2 0C, mango and guava are vapored with hot water for 30 minutes. Bactrocera zonata is killed and fruit is ready to be exported.
- Cold treatment
Cold treatment is very prolonged process and costly. Citrus and pomegranate are treated at 1.7 0C for 14 days. As result, all stages of Bactrocera zonata are killed away. So, the fruit is infestation free now.
Abu-bakar Sidique, Muhammad Yahya, Muhammad Shajar, Sheikh Muhammad Aqeel, Mujahid Tanvir
University college of Agriculture, University of Sargodha