Melon Fly

Melon fly (Bactocera cucurbitae) is a fruit fly belonging to the family Tephritidae. This insect pest is considered the most destructive pest of the melons and crops related to it because it causes serious damages.

Host & Distribution

Melon flies have a wide range of hosts in the Cucurbitaceae family. These include the following;

• Watermelon
• Cucumbers
• Edible gourds
• Pumpkins
• Butternuts

This insect pest is distributed all over the world, in temperate, tropical and subtropical regions.  In Kenya, it is found in areas where cucurbitaceous crops are grown. Its abundance increases when the temperature fall below 32 degrees centigrade and the relative humidity ranges between 60-70%.

Life Cycle

The female lays eggs under the skin of the fruit of the host plant. Eggs can also be laid into flowers, stems as well as exposed roots. Within 2-4 days, they hatch into larvae, usually maggots, which are very active. Larvae go through three instars feeding for about 4-7 days. As they become mature, they drop off the plant and burrow into the soil in order to pupate.  The pupal stage takes 7-13 days depending on the environmental conditions. After sometimes, adults emerge from the pupae and find their way out of the soil.

The cycle is continuous. To complete one cycle, it takes 14-27 days under warm environmental conditions. However, under cold conditions, a single cycle takes a longer period.

IDENTIFICATION

• Adults– they have wings which are patterned with a thick brown band and are slightly larger than houseflies, about 6-8mm long. Eyes and head are dark brown and bodies are yellowish brown with a yellow spot above the first pair of legs.
• Eggs– they are slender and white in colour. Their ventral surfaces are almost flat and are laid in bunches.
• Larvae– these are cylindrical maggot shaped, elongated with the anterior end narrowed. They are creamish white, legless and about 10mm long.
• Pupae– they are about 5-6 mm long and barrel-shaped. Their colors range from dull red or brownish yellow to dull white and are distinctly ringed by narrow yellow bands around each segment.

Feeding & Damage

The larval stage is the most destructive to the crop. These maggots tunnel through the flesh of the fruit or any other plant part, where the eggs were laid. While there, these maggots feed inside the fruit. Young attacked fruits become distorted and eventually fall off while the mature fruits develop a water soaked appearance. Infested flowers, stems or roots also become distorted and wilt in severe cases.

Behavior & Survival

Melon flies are strong fliers and remain active all year round on the host. When the ecological conditions are not favourable, the insects hide and huddle together under dried leaves of bushes, trees etc., or in shaded areas. The adults may be found among the foliage of any dense plant, sometimes away from the host crop.

Management

This pest can be controlled using a number of methods. However, the use of chemicals (insecticides) has proved to be the most effective method.

The following insecticides are effective in eradicating melon flies;

• OCCASION STAR^® 200SC 3ml/20L
• KINGCODE ELITE 10ml/20l
• PRESENTO 5g/20l
• LEXUS 8ml/20l
• PROFILE 30ml/20l
• PENTAGON 10ml/20l

NB; -Proper timing is very important

Always mix the insecticide with INTEGRA 3ml/20l. This is a sticker, spreader and a penetrant and helps in improving the efficacy of the product.

Other methods which can be used to manage this pest include;

• Use of baited traps
• Field sanitation
• Crop rotation with non-host plants
• Use of a protective covering to wrap the fruit while it develops
• Destroying the infested fruit (if it can’t be marketed) and disposing all the crop residues immediately after harvesting.