The melon fly, scientifically known as Bactocera cucurbitae, is a type of fruit fly that falls under the Tephritidae family. This particular insect is notorious for its devastating impact on melons and other closely related crops, as it inflicts significant damage.
Host & Distribution
Melon flies exhibit a broad spectrum of hosts within the Cucurbitaceae family, encompassing various crops such as watermelon, cucumbers, edible gourds, pumpkins, and butternuts.
This insect pest has a global distribution, thriving in temperate, tropical, and subtropical regions. In Kenya, it can be found in regions where cucurbitaceous crops are cultivated. The population of melon flies tends to rise when temperatures drop below 32 degrees Celsius, coupled with relative humidity levels ranging from 60% to 70%.
The female melon fly deposits her eggs beneath the skin of the fruit on the host plant. Additionally, eggs can be laid in flowers, stems, and even exposed roots. Within a span of 2-4 days, these eggs hatch, giving rise to highly active larvae, commonly known as maggots. The larvae undergo three growth stages, or instars, and feed for approximately 4-7 days. Once they reach maturity, they detach from the plant and tunnel into the soil for pupation. The pupal stage typically lasts 7-13 days, contingent upon the surrounding environmental conditions. Eventually, adult flies emerge from the pupae and exit the soil.
This life cycle repeats itself continuously. Under warm environmental conditions, a complete cycle is accomplished within 14-27 days. However, in colder conditions, the duration of a single cycle extends.
- Adults: The adult melon flies can be distinguished by their wings, which display a thick brown band. They are slightly larger than houseflies, measuring approximately 6-8mm in length. Their eyes and head exhibit a dark brown coloration, while their bodies are yellowish brown, with a yellow spot located above the first pair of legs.
- Eggs: The eggs of melon flies are slender and have a white coloration. They possess almost flat ventral surfaces and are laid in clusters or bunches.
- Larvae: The larvae of melon flies resemble elongated, cylindrical maggots. They have a creamish white coloration, are legless, and measure about 10mm in length. Their anterior end is narrowed.
- Pupae: The pupae of melon flies are barrel-shaped and have a length of approximately 5-6mm. They can exhibit various colors, ranging from dull red or brownish yellow to dull white. Each segment of the pupae is distinctly ringed by narrow yellow bands.
Feeding & Damage
Among the different stages of the melon fly’s life cycle, it is the larval stage that poses the greatest threat to crops. These maggots burrow through the flesh of the fruit or other affected plant parts where the eggs were deposited. Once inside, the maggots feed on the internal tissues of the fruit. As a result, young fruits that have been attacked become deformed and eventually detach from the plant, while mature fruits exhibit a water-soaked appearance. In severe cases, infested flowers, stems, or roots also experience distortion and wilting.
Behavior & Survival
Melon flies possess strong flying capabilities and maintain their activity throughout the year on the host plants. In instances when the ecological conditions are unfavorable, these insects seek shelter and gather together under dried leaves of bushes, trees, or other areas with shade. Adult melon flies can be found among the foliage of any dense plant, sometimes even away from the host crop.
There are several methods available to control the melon fly pest, but the use of chemical insecticides has proven to be the most effective approach.
The following insecticides have shown effectiveness in eliminating melon flies:
- OCCASION STAR® 200SC at a rate of 3ml/20L
- KINGCODE ELITE at a rate of 10ml/20L
- PRESENTO at a rate of 5g/20L
- LEXUS at a rate of 8ml/20L
- PROFILE at a rate of 30ml/20L
- PENTAGON at a rate of 10ml/20L
It is crucial to emphasize the importance of proper timing when using these insecticides.
To enhance the effectiveness of the product, it is recommended to mix the insecticide with INTEGRA at a rate of 3ml/20L. INTEGRA acts as a sticker, spreader, and penetrant, improving the efficacy of the insecticide.
In addition to chemical control, other methods can be employed to manage this pest, including:
- Use of baited traps
- Field sanitation
- Crop rotation with non-host plants
- Utilization of protective coverings to wrap developing fruits
- Prompt disposal of infested fruits and immediate removal of all crop residues after harvesting, especially if the infested fruit cannot be marketed.