Oriental Fruit Fly

Mediterranean Fruit Fly

One of the biggest challenges in farming  is controlling the medfly . In fact, if not managed, it can cause up to 80% crop loss. Ignore it at your own peril. Therefore, how does a farmer protect their crop?

 

The oriental fruit fly attacks over 300 cultivated and wild fruits including Annona (cherimoya, atemoya, sugar apple), avocado, banana, bittermelon, citrus, coffee, guava, macadamia, mango, papaya, passion fruit, peppers, persimmon, and tomato. This pest will apparently breed in all fleshy fruits.it is estimated that 95% of the oriental fruit flies develop on guava and mango, It does not attack cucurbit crops such as cucumber and squash.

DAMAGE

The damage to crops caused by medfly result from 1) position in fruit and soft tissues of vegetative parts of certain plants, 2) feeding by the larvae, and 3) decomposition of plant tissue by invading secondary microorganisms.

Larval feeding in fruits is the most damaging. Damage usually consists of breakdown of tissues and internal rotting associated with maggot infestation, but this varies with the type of fruit attacked . Infested young fruit becomes distorted, callused and usually drop; mature attacked fruits develop a water soaked appearance. The larval tunnels provide entry points for bacteria and fungi that cause the fruit to rot. When only a few larvae develop, damage consists of an unsightly appearance and reduced marketability because of the egg laying punctures or tissue break down due to the decay

 

BIOLOGY

Development from egg to adult takes about 16 days . Developmental periods may be extended considerably by cool weather.

EGGS

flies insert eggs under the skin of fruit in clusters of 10 to 50 about 1/25 to 1/8 inch below the fruit surface. The eggs measure about 1/25 by 1/250 inch and are white, elongate, and elliptical. They hatch in 1-1/2 days.

LARVAE

The white larva is legless, and resemble an elongated cone. The mouth is at the pointed end of the body. There are 3 larval stages, or instars. The third instar is about 2/5 inch long. The entire larval stage lasts for 11-15 days.

PUPAE

When mature, larvae drop to the ground and pupate in the soil. The puparium is yellowish-brown and seed-like. Adults emerge in about 10 days.

ADULTS

The color of the fly is highly variable but mostly yellow with dark markings on the thorax and abdomen. Generally, the abdomen has two horizontal black stripes and a longitudinal median stripe extending from the base of the third segment to the apex of the abdomen. These markings may form a "T" shaped pattern, but the pattern varies considerably.

Females begin to lay eggs about 8 days after emergence from the puparium. Under optimum conditions, a female can lay more than 3,000 eggs during her lifetime, but under field conditions approximately 1,200 to 1,500 eggs per female is considered to be the usual production. Ripe fruit are preferred for egg laying, but immature ones may be also attacked.

MANAGEMENT

In conjunction with the post-harvest quarantine treatments, it is helpful to apply pre-harvest management practices to reduce fruit fly populations. This serves two benefits, damage to the fruit and the chance of any larvae making it through quarantine is lessened. Since the discovery of the oriental fruit fly in Hawaii a number of methods have been employed in attempts to reduce or prevent damage by this pest. They include: 1) mechanical control, 2) cultural control, 3) biological control, 4) post-harvest quarantine treatments and 5) chemical control.

Mechanical Control

Mechanical methods of controlling the oriental fruit fly include the use of protective coverings on the fruit and the destruction of adults by use of traps. Shrubs within 100 yards of larval hosts may be used advantageously in placing traps. The use of protective coverings is more effective and costly than the use of traps.

2) kangeta kilimo Protein food bait

Whereas, the male annihilation technique targets the male, the protein food bait method focuses on the female.  For the young female fruit fly to reach sexual maturity it has to feed on protein.  It will also need it to develop eggs. They feed on protein found in the leaf and the fruit surface.When the female start to lay eggs they stop consuming protein. Just like the male annihilation technique, this method targets the behavior of the female. In this method a protein laced with a soft toxin is used to kill the fly. This method prevents the female from laying eggs. Hence, the population of the fruit fly is controlled.Notably, at least two thirds of the captured insects are female and the other third are male.

For an acre, you will need 5 traps fo. The spacing from trap to trap should be 50meters. The trap should be filled with 400 ml of the solution. Collect the catches every week and sieve. Just like the pheromone trap the changing of the solution should be done after 78 days. If there is a high rate of evaporation  change kangetakilimo trap after 78days.

3) Bio pesticides

 Unfortunately, the over reliance on synthetic pesticides has caused pesticide resistance in many parts of the world. The melon fly is no different. The use of bio pesticides derived from fungi can help the situation.  Metarhizium anisopliae is a form of fungus that occurs naturally in the soil. The fungi isolate strain 69 can be used to control the melon fly.

These fungi can be used as a soil inoculant or a spray. When applied to the soil, the granules of the fungi are raked in before fruiting. Since the pupae burrow in the soil before they mature into adults the fungi will kill them before they morph into adults. 

 The other way of using the fungi is through an oil based spray. When sprayed the fungus spores bind to the exoskeleton of the bactocera fruit fly. Once the fungus enters the insect it grows rapidly and it dies. Insects that come into contact with the infected insect also become infected and die.

4) Cultural control

 To bolster the aforementioned methods, cultural control is important as well.  This can be done through field sanitation and planting a trap crop. While starting your season plant a border crop like maize that will serve as the host plant for pests. The crop will also help in managing aphids; another troublesome pest in watermelon.

 For the infected fruit ensure it is collected and destroyed. The fruit should be put in a plastic bag to kill the fruit fly maggots or they be buried in a 3 feet deep hole. Add lime to kill the larvae. This should be done at least twice a week. Finally, rotate the watermelon with non-host crops (non cucurbits) for at least 3 seasons before planting again in the same spot. Ultimately, there should be no buildup of pests.

 Conclusion

 The choice of control will depend on the level of infestation, method of production (organic or inorganic), and costs. It is best to start control at flowering i.e. week 4. Strive for prevention to stop any economic injury. In conclusion, always seek for an integrated pest management approach. It is more chilled out on the environment.

 

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