Tuesday, July 1, 2014

Pheromone-Based Mating Disruption Reduces Pest Attack on Dates and Results in New Registration

 —by Tom Perring,UC Riverside; Michael Braverman,  IR-4 Biopesticide and Organic Support

Program Manager; Agenor Mafra-Neto, President, ISCA Technologies, Inc. Riverside CA
Figure 1. Carob moth, Ectomyelois ceratoniae (Zeller), adult on date fruit.
In the United States, commercial date, Phoenix dactylifera L., production occurs predominantly in the Coachella Valley (Riverside Co., CA), although recent plantings of dates have taken place in the Bard/Winterhaven area of Imperial Co., CA, and near Yuma AZ.  In 2012, dates were harvested from 8400 acres, producing a crop worth $41.6 million (USDA 2013).  Two varieties make up most of this production, Deglet Noor and Medjool.  These dates are subject to attack by the carob moth, Ectomyelois ceratoniae (Zeller) (Figure 1), which first was observed in California in 1982 (CDFA 1983).  Currently, it is the primary economic pest of commercial dates; fruit infested with larvae (Figure 2) can cause damage reaching 10-40% to the harvestable crop each year (Warner 1990a, Nay et al. 2006).
Figure 2. Carob moth, Ectomyelois ceratoniae (Zeller), larvae in date fruit.



Various carob moth management strategies are available for growers. These include over-winter (Carpenter and Elmer 1978) and in-season (Warner et al. 1990a, 1990b) removal of waste dates that fall to the garden floor.  Dislodging abscised kimri dates (fully expanded, green dates) and khalal dates (fully expanded, brown, unripe dates) from bunches during August with a bunch cleaning tool (Nay et al. 2006, 2007) exposes larvae in the fruit to predation and heat (Nay and Perring 2005).  Another strategy is center cut strand thinning of date bunches to facilitate abscised fruit drop to the ground (Nay and Perring 2009).  Also, mesh bags can be used to exclude carob moth from the date bunch (Perring, unpublished data).  In addition to these methods, there are 3 registered insecticides:  Delegate (spirodiclofen), Intrepid (methoxyfenozide), which was registered through support by IR-4, and Malathion dust. Malathion dust (Figure 3) was the industry standard until 2010, when environmental concerns and the emergence of new chemicals and technologies, resulted in growers no longer using this material. 



Figure 3. Application of Malathion dust  for carob moth control in dates.

Mating disruption involves the use of a pheromone scent to interfere with male moths locating females. Through the collaborative efforts of the University of California, Riverside, ISCA Technologies, Inc., and the California Date Commission, a formate mimic of carob moth pheromone (Z7, E9, 11-dodecatrienyl formate), mixed in a 2% formulation with a biodegradable wax carrier (SPLAT®  ), was developed. This formulation, SPLAT EC™ (SPLAT Ectomyelois ceratoniae), when applied in a 2.5 g “dollop” (Figure 4) to the date palm trunk
Figure 4. SPLAT EC-O “dollop” on date palm trunk.




Figure 5. Application of SPLAT EC-O on date palm trunk with hand applicator.


(Figure 5) resulted in very low male trap counts, suggesting that males were confused by the pheromone scent and were unable to locate females.  More importantly, a one-time application of SPLAT EC™ provided season-long control, resulting in a similar number of carob-moth infested fruit as the Malathion treatments, and significantly fewer infested fruit compared to non-treated controls.

In 2007-2008, with Malathion as the only registered chemical for use against the carob moth, the IR-4 Biopesticide Grant Program funded a project to study the impact of application timing of SPLAT EC™ on male trap catches and subsequent fruit infestation.  The results from this research showed that an application in early August did not protect the crop through the growing season, whereas an application in early September provided control.  This prompted a second study funded in 2009-2010 by the Grant Program to evaluate application timing, placement in the date palm, and rate of SPLAT EC™ on trap shutdown and carob moth-infestation of dates at harvest. These parameters all have bearing on the final cost and adoption of the mating disruption strategy.

Studies were conducted using large plots (4 acres = approx. 200 palm trees) replicated 3 times. Experiments in 2009 showed that early August treatments resulted in trap shutdown. However, this did not hold through the season. A second treatment reduced the male moth catches. At harvest, there were no differences in the three timing treatments. Given that it is more expensive to apply multiple times throughout a season, a single application time around the first week of September appears best.  In 2010, three rates (4%, 3%, and 1%) of the pheromone mimic were evaluated. With respect to the rate of application, all three rates shut down trap counts and had comparable infestations at the end of the season. This suggests that growers could apply 1%, 2% or 4% rates and achieve the same result.  However, the study in 2010 showed higher male moth counts in late September and October than in 2009, and the overall infestation was higher in 2010 than 2009.  This may have resulted from an overall lower amount of SPLAT EC™ that was distributed in the date garden in 2010 as compared to 2009, which resulted in more males finding females. This, in turn, resulted in a higher general infestation in the field in 2010. Based on these studies, a 4% application of SPLAT EC™ (2% in bunches and 2% on the trunk at chest height) during the first week of September consistently led to positive results over the past four years of study. Males are confused because they can’t find a female to mate with. Mating disruption with a carob moth pheromone mimic protects the harvestable crop and is as effective as Malathion dust.

Registration
ISCA Technologies, Inc. (Riverside, CA) synthesized the carob moth pheromone mimic (Z7, E9, 11-dodecatrienyl formate) and developed and optimized the use of SPLAT® (Specialized Pheromone & Lure Application Technology) to apply the material.  With the current label SPLAT EC-O (SPLAT Ectomyelois ceratoniae Organic), ISCA Technologies has launched a regional marketing campaign aimed towards SPLAT EC-O availability to date growers.  Other than removal of waste dates and using mesh bags, both of which can be expensive and very labor intensive, this is the only organic solution for the control of carob moth. The response in the date industry has been strong, and ISCA Technologies expects a fast adoption of the product in the date industry. Since this mating disruption product has been developed in close partnership between all of the stakeholders, including date growers, funding agencies (IR4 and USDA), academia (UCR) and private industry (ISCA Technologies), SPLAT EC-O is gaining popularity in the Coachella Valley. 
Application of SPLAT pheromone using a
hand applicator
 

Acknowledgement
We wish to thank the California Date Commission and Chairman, Albert Keck, for their support of this project.

References Cited
Carpenter, J. B., and H. S. Elmer. 1978. Pests and diseases of the date palm. USDA Agricultural Handbook No. 527.

(CDFA) California Department of Food and Agriculture. 1983. Carob moth in California, pp. 11-14. In R. Gill and S. Kaiser (eds.) California plant pest and disease report, vol. 2. CDFA, Sacramento.

Nay, J. E., E. A. Boyd, and T. M. Perring. 2006.  Reduction of carob moth in ‘Deglet Noor’ dates using a bunch cleaning tool.  Crop Protection 25: 758-765.
Nay, J.E. and T. M. Perring.  2005. Impact of ant predation and heat on carob moth (Lepidoptera: Pyralidae) mortality in California date gardens.  J. Econ. Entomol.  725-731.

Nay, J. E., Y. L. Park, and T. M. Perring. 2007. Effect of bunch sanitation on spatial distribution of abscised fruit and phycitine moths (Lepidoptera: Pyralidae) in California date gardens. J. Econ. Entomol. 100: 1773-1780.

Nay, J. E., and T. M. Perring. 2009. Effect of center cut strand thinning on fruit abscission and Ectomyelois ceratoniae (Lepidoptera: Pyralidae) infestation in California date gardens. J. Econ. Entomol. 102: 948-953.

USDA 2013. Noncitrus fruits and nuts, 2012 preliminary summary. (usda.mannlib.cornell.edu/usda/current/NoncFruiNu/NoncFruiNu-01-25-2013.txt)

Warner, R. L., M. M. Barnes, and E. F. Laird. 1990a. Chemical control of a carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae), and various nitidulid beetles (Coleoptera: Nitidulidae) on ‘Deglet Noor’ dates in California. J. Econ. Entomol. 83: 2357-2361.

Warner, R. L., M. M. Barnes, and E. F. Laird. 1990b. Reduction of insect infestation and fungal infection by cultural practice in date gardens. Environ. Entomol. 19: 1618-1623.

ISCA has provided US date growers access to semiochemical pest management tools that are as effective as synthetic chemicals. In 2012, IR-4 set up a meeting for ISCA Technologies with EPA to discuss the registration requirements. IR-4 also consulted in the development of some of the regulatory packages submitted to EPA.  With some additional follow-up by ISCA Technologies, the carob moth pheromone active ingredient and user product, SPLAT EC-O, became registered with EPA at the national level in 2013.  Registration at the state level ensued, and in April 2014 the product was approved by the California Environmental Protection Agency (Cal/EPA) for commercialization in the state.





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