An Invasive Fly from Asia Means African Mango Farmers Must Spray to Protect Their Crop


Ruined Mangoes

In 2003, a new invasive fruit fly from Asia was detected in Africa. The pest has spread across a north-south distance of over 5000 km in West Central Africa. The female fly implants its eggs in young mango. The larvae or maggots develop in the flesh of fruit by digging tunnels (which provide opportunities for secondary infections when the larvae emerge from the fruit).

Bactrocera invadens… is a recently described fruit fly species from Asia that is of major quarantine concern in Africa and elsewhere.

On mango, direct damage owing to B. invadens has been reported to range from 30 to 80% of the crop depending on the cultivar, locality, and season. In addition to direct losses, indirect losses attributed to quarantine restrictions on the pest have been enormous.

The European Union (EU) phytosanitary regulations in relation to non-European Tephritidae are tightening and interception and rejection of African mangoes in the EU, owing to fruit flies, have been on the increase since the arrival of B. invadens. These direct and indirect costs have wide reaching socioeconomic implications for millions of people in rural and urban communities involved in the mango value chain across Africa.

In this study, we evaluated the relative efficacy of six commercially available food-based attractants in trapping male and female B. invadens in mango. Furthermore, we evaluated the efficacy of the most attractive bait, sprayed in conjunction with spinosad for field suppression of B. invadens in mango orchards in Kenya during two fruiting seasons.

At harvest, the proportion of fruit infested was significantly lower in the treated orchards (8%) compared with the control orchards (59%). Estimated mango yield was significantly higher in orchards receiving the bait sprays (12,487 kg/ha) compared with control orchards (3,606 kg/ha). Based on bait spray costs, yield data, and monetary gains, a cost-benefit ratio of 1:9.1 was realized, which is acceptable for growers.”

Authors: Ekesi, S., et al.
Affiliation: International Centre of Insect Physiology and Ecology, Kenya.
Title: Comparison of Food-Based Attractants for Bactrocera invadens (Diptera: Tephritidae) and Evaluation of Mazoferm-Spinosad Bait Spray for Field Suppression in Mango.
Source: Journal of Economic Entomology. 2014. 107[1]:299-309.

Zero Tolerance for Maggots in Cherries Means Growers Must Spray

Cherry Maggot

Cherry Maggot

Pairs of cherry fruit flies have been observed copulating for 18 hours at a time. Each female may deposit 100 to 300 eggs under the fruit skin over a period of thirty days. Eggs hatch in 3-7 days and young maggots feed on cherry flesh, mainly around the pit. Maggots and their frass within the fruit render the product unsalable.

“Insecticides continue to be vital in efforts to control the western cherry fruit fly, the most serious insect pest of commercial sweet and sour cherries in the western United States. … The zero tolerance for fly larvae in cherries has necessitated the use of these highly toxic insecticides in commercial orchards. Isolated homeowner or abandoned trees can be heavily infested and also need to be treated with these insecticides to reduce chances of flies dispersing to commercial orchards.”

Authors: W.L. Yee1 and D.G. Alston2
Affiliation: 1USDA-ARS, Yakima Agricultural Research Laboratory, Wapato, WA; 2Department of Biology, Utah State University, Logan, UT
Title: Effects of spinosad, spinosad bait, and chloronicotiny insecticides on mortality and control of adult and larval western cherry fruit fly (Diptera: Tephritidae).
Publication: Journal of Economic Entomology. 2006. 99(5):1722-1732.