Title: A comparison of bioinsecticide, Spinosad, the semi-synthetic insecticide, Spinetoram and synthetic insecticides as soil drenches for control of Tephritid fruit flies Authors
Submitted to: Biopesticides International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2013
Publication Date: December 1, 2013
Citation: Stark, J.D., Vargas, R.I., Souder, S., Fox, A.J., Smith, T.R., Mackey, B.E. 2013. A comparison of bioinsecticide, Spinosad, the semi-synthetic insecticide, Spinetoram and synthetic insecticides as soil drenches for control of Tephritid fruit flies. Biopesticides International . 9(2):120-126. Interpretive Summary: Annual introductions of Tephritidae fruit flies often result in temporary trade restrictions and associated area-wide eradication treatments, lasting up to 9 months before movement of agricultural commodities can resume without postharvest treatments. Although most of the fruit fly control efforts world-wide involve protection of food, nursery stock can also be affected due to quarantine restrictions. In California, quarantine regulations designed to prevent the movement of flies from infested areas can severely impact the movement of fruiting nursery stock within the state and out of the state. The nursery industry in California is one of the largest agricultural industries in the State, and ranks as one of the top five commodities in monetary value. At present, to ship fruit tree nursery stock out of the state, container pots with fruit seedlings and small trees must be drenched with diazinon prior to shipment. Although many uses of diazinon have been discontinued in the United States due to problems with its effects on aquatic organisms in freshwater ecosystems, it is still used in California via a Special Local Needs(SLN) registration. Diazinon is an organophosphate insecticide which has been banned for outdoor residential use by the U.S. Environmental Protection Agency. Alternative insecticides for quarantine treatment of nursery stock in California are needed to replace diazinon so as to allow fruiting nursery stock to continue to be sold in the event that diazinon is no longer available. The objective of this study conducted by the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) was to evaluate several insecticides for their efficacy as controls of the larval and pupal stages of pest fruit flies in soil. Several reduced risk insecticides significantly reduced adult emergence after exposure as pupae. Overall, Entrust, a natural product (spinosad), and its synthetic counterpart, Radiant SC were quite effective at reducing adult emergence from sand and may be good alternatives to diazinon.
Technical Abstract: Eight insecticides, including the natural bioinsecticide spinosad and the semi-synthetic insecticide spinetoram, as well as two synthetic pyrethroids, an insect growth regulator, an anthranilic diamide, and an organophosphate were evaluated as soil drench treatments for control of three economically important tephritid fruit fly species, the Mediterranean fruit fly, Ceratitis capitata, the melon fly, Bactrocera cucurbitae, and the oriental fruit fly, Bactrocera dorsalis. Specifically, we evaluated Entrust (Spinosad), Radiant SC (Spinetoram), Force CS (Tefluthrin), Force 3G (Telfluthrin), Warrior II (Lambda-Cyhalothrin), GardStar 40% EC (Permethrin), Cyazypyr (Cyantraniliprole), an Intrepid 2F (Methoxyphenocide) in the laboratory for control of these three species and compared their efficacy to Diazinon AG600 (diazinon), the insecticide presently used as a soil drench by the nursery industry in California. Two experiments were conducted. In the first,late third-instars ready to pupate were exposed to insecticide-treated sand. In the second experiment, pupae were placed in insecticide-treated sand. Adult emergence was the endpoint evaluated. All of these insecticides, except Intrepid 2F, significantly reduced adult emergence of all three species after exposure as third instars, compared to the control. All insecticides, except Cyazapyr, significantly reduced adult emergence of all three species after exposure as pupae. Cyazapyr significantly reduced adult emergence in C.capitata and B. dorsalis, but not in B.cucurbitae. Radiant SC was not as effective against the larval stage as Diazinon AG600, Warrior II, Force CS, Entrust or Gardstar 40% EC, but still quite effective. Overall, Entrust, a natural product (spinosad) and its synthetic counterpart, Radiant SC were quite effective at reducing adult emergence from sand and may be good alternatives to the synthetic pyrethroids, Warrior II, Force CS, and GardStar 40% EC.