BACTROCERA OLEA

BACTROCERA OLEA “OLIVE FRUIT FLY”

The olive fruit fly, Bactrocera oleae , is a widespread, monophagous pest that feeds exclusively on wild and cultivated olives . Genetic studies suggest that this fruit fly is native to Africa, where its original host plants were wild precursors of the cultivated olive. The widespread distribution of this pest is likely due to the geographical spread of olive growing operations.

Distribution

The olive fruit fly is found almost anywhere cultivated olives are grown or wild olives naturally occur. The olive fruit fly has been reported in Africa, the Canary Islands, the Middle East, China, California, Mexico, and Central America .

Life Cycle and Biology

The female deposits eggs inside developing olives, using her serrated ovipositor to make a cut in the olive skin. Eggs hatch two to three days later and the larvae begin feeding on the olive flesh .The larval stage lasts around 20 days. Pupation can occur within the olive fruit or in the soil. Pupation in the soil is more likely in winter months and this stage can last up to six months; pupation within the olive fruits lasts around 8-10 days. Unlike the larvae, adults do not feed on olives, but on nutrient-rich substances such as honeydew and bird droppings . The female olive fruit fly has been reported to lay as many as 500 eggs in her lifetime of less than six months. In warm areas with abundant host plants, the olive fruit fly may produce up to five or six generations per year.

Hosts

Larvae of the olive fruit fly feeds only on the fruit of wild and cultivated olive trees (Olea spp.). Susceptible wild species include Olea verrucosa,Olea chrysophylla, and Olea europaea, the latter of which can be found in both cultivated groves and in the wild . Female flies have shown oviposition preference for larger table olive species.

Damage

The oviposition activity of the females as well as larval feeding are responsible for the destruction of olive fruits. Cuts in the olive skin from the ovipositor and the larval feeding on the olive flesh can cause olive fruits to dry out and fall from trees. In addition, the oviposition behavior of the olive fruit fly increases the fruit’s susceptibility to bacterial and fungal pathogens. Infested olives completely lose their market value for table consumption and oil production . Damage thresholds for the olive fruit fly vary by region, but are typically low.

Management

Cultural control

Field sanitation is a critical step in preventing outbreaks of the olive fruit fly. Any fruits that remain in the field (on the tree or on the soil) may contain eggs or larvae, contributing to the olive fruit fly population. Crop IQ offers Attrcat and Kill gel and Bait sprays for the olive fruit fly, wherein attractant sprays containing insecticide are applied to the field in concentrated areas. This method is effective at eliminating female olive fruit flies, which are attracted to ammonia-containing proteins when they are preparing for egg production. Mass trapping is another common technique. This method also involves chemical attractants like those used in the spray method, Bait spraying and mass trapping are both effective in controlling olive fruit fly populations, though mass trapping may be preferred because it does not require chemical application to the crop plants themselves.

Biological Control

Many insects have been investigated as potential biological control agents of the olive fruit fly. recommended a small group of braconid wasps that parasitize the olive fruit fly in its native range. Braconid species shown to parasitize olive fruit fly include Psyttalia lounsburyi, Psyttalia concolor, Psyttalia ponerophaga, Utetes africanus, and Bracon celer, with parasitoid abundance and efficacy varying over different geographic locations. Psyttalia concolor has shown mixed results as a biological control organism following releases aimed to control the Mediterranean fruit fly.

Many other parasitoid wasps are found in regions where the olive fruit fly is considered a pest, but they are often not sufficiently abundant to provide control. Common beneficial insects like ladybird beetles (Coccinellidae) and lacewings (Chrysopidae) are ineffective in controlling the olive fruit fly because these insects prey upon the immature stages of pests, which, in this case, are sequestered within developing olives .

Sterile Insect Technique

Sterile insect releases have been proposed as an effective and environmentally-friendly method of control for the olive fruit fly. This control method involves the rearing and release of large numbers of sterilized male fruit flies. When these males mate with wild female flies, viable eggs cannot be produced. Thus, the next generation of pest flies is greatly reduced. Over time, this could eradicate the pest population. Sterile insect releases have many benefits; this method is species-specific, environmentally sound, and relatively speedy. Drawbacks to this technique lie in the initial set up of the program, such as guaranteeing a place to rear the flies, choosing a reliable sterilization method, and timing the release of the flies. Also, females laying sterile eggs will still damage fruit with their ovipositors. This technique has been a successful management strategy for many destructive pests, like the Mediterranean fruit fly, Ceratitis capitata , which can cause widespread damage due to its oviposition behavior and relatively broad host range.

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BACTROCERA OLEA

BACTROCERA OLEA “OLIVE FRUIT FLY”

How to control BACTROCERA OLEA ?

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