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| Fig. 1: Female Mediterranean Fruit Fly Laying Eggs on Citrus. (Courtesy of the USDA. Photo credit: Scott Bauer) |
The Mediterranean fruit fly is responsible for the destruction of over 300 different types of fruits, nuts and vegetables home to the endemic Argan forest which is the main breeding ground for the medfly. [1] Researchers attempted to combat the medflies through the use of pesticides, but were unable to significantly reduce the numbers and ensure no major problems inflicted on the environment and/or humans from the use of pesticides. The Mediterranean fruit fly remained a problem in Morocco and many other areas in the Mediterranean, South America and Australia and a solution was in search. [1]
Many approaches were taken to decrease the number of medflies, but overall, the most effective solution was the Sterile Insect Technique (SIT). SIT, which sterilizes insects/flies with X-ray radiation, is used when one specific insect is overwhelming a particular produce; in this situation SIT was successful in targeting the Mediterranean fruit flies and decreasing their destruction to agriculture. The female flies are actually the ones that cause the damage to the fruit by laying their eggs, therefore, the reproduction of females is the main focus of control. [2] The image on the side portrays a female Mediterranean Fruit Fly laying her eggs on citrus which will cause damage to the produce. (See Fig. 1) If both insects were to be sterilized then the male flies are more likely to mate with sterile females which is not an effective use of the sterile males. However, if only the male flies are sterilized then they are more likely to disperse and mate with wild females and inhibit their reproduction possibly resulting in their death. It is more effective in the widespread view to sterilize only the male insects, however, it is also more difficult, costly and time consuming to distinguish the two specificities and only target the male flies. [3] Overall, both tactics will be successful in reducing the number of medflies and possibly ending their existence in a particular area.
The FAO/IAEA Programme on Nuclear Techniques in Food and Agriculture have been focused on SIT for four decades because widespread use would decrease the use of pesticides and result in major benefits to humans and the environment. Overtime, it is necessary to increase the amount and intensity of chemicals in pesticides because the flies/insects become immune and pass on genes that prepare the next generation to withstand higher amounts of chemicals. Pesticides cause health risks for consumers because they have residue on the produce the consumers eventually eat. However, the replacement of SIT for pesticides is healthier for humans and the environment; a decrease in the amount of pesticides used would increase plant, animal and human health and allow for a cleaner environment and atmosphere. [4]
© Monika Sivilli. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] A. Alaoui et al., "Genetic Structure of Mediterranean Fruit Fly (Ceratitis capitata) Populations from Moroccan Endemic Forest of Argania spinosa," Int. J. Agric. Biol., 12, 291 (2010).
[2] D. Starwalt, "The Sterile Insect Technique," Physics 241, Stanford University, Winter 2015.
[3] J. Hendrichs, G. Franz and P. Rendon, "Increased Effectiveness and Applicability of the Sterile Insect Technique through Male-Only Releases for Control of Mediterranean Fruit Flies During Fruiting Seasons," J. Appl. Entomol., 119, 371 (1995).
[4] J. R. Carey, "Establishment of the Mediterranean Fruit Fly in California," Science 253, 1369 (1991).