African Fig Fly: A New Pest in Mississippi?

Today I have posted a guest article from USDA-ARS authors, Chris Werle, Blair Sampson, and John Adamczyk on African Fig Fly.

African Fig Fly: Another Potentially-Destructive Fly Discovered in Mississippi

                Several new challenges have been brought to our attention during the blueberry season of 2012, including the exotic-invasive Spotted Wing Drosophila (SWD), Drosophila suzukii (Matsumura).  SWD is attracted to the odors given off by fermented fruit (alcohol or vinegar), so personnel from the Thad Cochran Southern Horticultural Lab (TCSHL) in Poplarville have implemented a wide-ranging SWD monitoring program using alcohol/vinegar traps this spring.  This monitoring research has yielded much interesting data on the insect community in and around blueberry orchards, including the discovery of a new MS record for both Genus and Species of Drosophilid, Zaprionus indianus (Gupta).  Commonly known as the African fig fly (AFF), it has become established as an important pest of commercial fruit production in tropical areas of the Americas (Vilela 1999).  Valuable crops including figs and longans have been impacted from Brazil to Panama, and AFF has been collected from a variety of hosts in Florida as early as 2005 (van der Linde et al. 2006).  Its impact on the Mississippi fruit industry is not yet known, but we report here a description of this potentially-destructive fly, along with recommendations for limiting damage.

                A native of tropical regions in Africa, AFF measures approximately 3.5 mm, with a very striking pair of white stripes that extend dorsally from the antennae to the tip of the thorax.  Two more shorter stripes extend laterally across the post-pronotum to the wing base.  On the head, these white stripes are bordered medially by black stripes and laterally by the distinctive red eyes, while the thoracic stripes are bordered on either side by the black.  These stripes contrast strongly with the otherwise yellow-orange body, making for a rather attractive little fly.

                Biological research conducted on AFF has shown they can survive an average of 82 (male) to 93 (female) days, with number of offspring averaging 58 per female (Setta and Carrereto 2005).  In the same study, development time was approximately 19 days from egg to adult.  While it is possible that this data may differ markedly from what happens in the field in Mississippi, it is likely that these flies are capable of producing numerous generations in a season.

                Research conducted in Florida has shown that AFF can be reared from over a dozen species of fruiting plants, but in most cases the infested fruits were collected from the ground or were otherwise damaged (Steck 2005).  The only exceptions were Malpighia emarginata (Barbados cherry) and Dimocarpus longan (longan), neither of which are grown in Mississippi (van der Linde et al. 2006).  Of concern to Mississippians is the fact that AFF can infest healthy, undamaged fig fruits, with fig production being reduced by 40-50% in some areas of Brazil (Vilela 1999).  The prevalence of figs grown in the MS home landscape will provide ample habitat for this new pest, and similar to SWD, a wide host range indicates that it may be able to survive on numerous wild hosts.  AFF has even been collected in a National Forest far from any commercial orchards (van der Linde et al. 2006), leading us to believe that eradication of this fly is unlikely, and effective control may also prove difficult.

                While direct damage from AFF to MS fruit crops may not become commonplace, the advent of the SWD along with other primary insect pests will provide the opportunity for AFF to thrive in orchards, and possibly into packing houses.  As with most insect pests, monitoring will be vital to the successful control program, and AFF is readily collected with the same vinegar/etoh traps that have proven so effective with SWD.  Once detection occurs, preventative insecticidal sprays can be applied in the same manner recommended in our previous pest alert for SWD (Sampson et al. 2012).  As always, please check with your local County Agent and refer to product labels for correct usage.  Additional cultural controls can be utilized, including the removal of wild native hosts like wild grape, dewberry, pokeweed, mulberry and elderberry.  If sanitation is practical, removal of berries from the ground may further prevent AFF from establishing large populations in your orchard.

                Research is being planned and conducted by TCSHL personnel and our cooperators to develop new and more effective control measures for use in fruit crop IPM, including better cultural practices, the encouragement of natural enemies, and to answer the questions below:

What % of traps had AFF?  What was their population numbers compared with SWD?  What time of year did they start to show up?

See image below to see what the fly looks like in comparison to a SWD fly.

References Cited

de Setta, N. and C. M. A. Carareto.  2005.  Fitness components of a recently-established population of Zapronius indianus (Diptera, Drosophilidae) in Brazil.  Iheringia, Ser. Zool., Porto Alegre.  95(1): 47-51.

Sampson, B. E. Stafne, J. Adamczyk, S. Stringer, D. Marshall.  2012.  Spotted wing Drosophila: A new invasive pest of Mississippi berries.  Miss. Vaccinium J.  1(3): 3-9.

Steck, G. J.  2005.  Zaprionus indianus Gupta (Diptera: Drosophilidae), a genus and species new to Florida and North America.

van der Linde, K., G. J. Steck, K. Hibbard, J. S. Birdsley, L. M. Alonso and D. Houle.  2006.  First records of Zaprionus indianus (Diptera: Drosophilidae), a pest species on commercial fruits from Panama and the United States of America.  Fla. Entomol.  89(3): 402-404.

Vilela, C. R.  1999.  Is Zapronius indianus Gupta 1970 (Diptera, Drosophilidae) currently colonizing the Neotropical region?  Drosophila Inf. Serv.  82: 37-39.

African Fig Fly (left) and SWD (right)

African Fig Fly (left) and SWD (right).  Note larger size and defined stripes on the AFF.

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