Use of Pheromones in IPM Thomas C

P1: aaa 9780521875950c21 cuuk358/Radcliffe ISBN: 978 0 521 87595 0 Top: 0.29637in Gutter: 0.79034in August 6, 2008 14:55 Chapter 21 Use of pheromones in IPM Thomas C. Baker During the past 68 years that have elapsed since ing crop damage after conducting experiments in the identification of the first insect pheromone which disruptant dispenser dosages and deploy- (Butenandt, 1959) there has been a bourgeoning ment densities have been varied. A mating dis- of basic and applied research that has resulted ruption system may work successfully from a bio- in an amazingly diverse and effective use of logical standpoint, but at the commercial level it pheromones in IPM. Other behavior-modifying may be too costly or not sufficiently user-friendly semiochemicals have had more limited success compared to standard practices, and the system on a commercial level, although much research is will have been judged to “fail” at this level. It is continuing to try to find new ways to make such important to distinguish between failure in the chemicals as host plant volatiles more useful in commercial arena versus biological failure of the IPM settings as attractants or deterrents. mating disruption system itself. Although pheromones have established themselves in IPM systems, most end-users and even applied researchers do not realize how much work 21.1 Monitoring established goes into identifying and optimizing pheromone populations blends so that they become highly species-specific and optimally attractive to the target species so that they can be used to the best effect. Research The most widespread use of pheromones has to determine the most effective pheromone blend been for monitoring endemic pest species’ compositions and dispenser dosages for monitor- adult populations. Comprehensive apple IPM ing and detection typically takes five to ten years programs that were initiated in New York State to complete. Optimizing trap design targeting par- and Michigan during the early 1970s were based ticular species can take several more years. Some- on good, species-specific monitoring traps for times effective pheromones cannot be elucidated the complex of tortricid moth pests that cause at all despite decades of intensive effort. direct and indirect damage to fruit. Monitoring Delivery of effective commercial products of leafroller pests coupled with computer assisted presents another hurdle. For instance, applied degree-day models (Riedl & Croft, 1974; Riedl et al., pheromone researchers may spend years estab- 1976) allowed sprays to be timed for optimum lishing that a particular mating disruption system efficacy against eggs and first instars on such is highly effective at disrupting mating and reduc- key pests as the codling moth (Cydia pomonella)and Integrated Pest Management, ed. Edward B. Radcliffe, William D. Hutchison and Rafael E. Cancelado. Published by Cambridge University Press. C Cambridge University Press 2009. P1: aaa 9780521875950c21 cuuk358/Radcliffe ISBN: 978 0 521 87595 0 Top: 0.29637in Gutter: 0.79034in August 6, 2008 14:55 274 THOMAS C. BAKER oriental fruit moth (Grapholita molesta). Spray-or- since the 1970s, the California Department of Food no-spray decisions based on abundance of adults and Agriculture (CDFA) has monitored an exten- in monitoring trap grids were also made possi- sive grid of pheromone traps to protect against the ble by effective, standardized monitoring traps pink bollworm becoming established in the Cen- and deployment schemes developed against some tral Valley of California. The grid density averages pests such as the codling moth (Madsen, 1981). approximately one trap per 250 ha, but it extends During the mid-1970s to late 1980s, insecticide at various densities throughout the Central Valley applications were reduced by more than 50% in (Baker et al., 1990). When a male moth is discov- New York State, Michigan and the Pacific North- ered in a trap, an airdrop of sterile moths, reared west due to monitoring programs that improved at the USDA-APHIS sterile pink bollworm moth- decision making about the need to spray insecti- rearing facility in Phoenix, is implemented. The cides (Madsen, 1981) as well as their timing. Such plane is guided to the exact field by GPS coordi- programs have become even more refined over nates. Sterile moths are dyed pink by the diet they the years, with concomitant further reductions ingest at the rearing facility, and so the many ster- in insecticide applications being documented ile males captured in the pheromone traps are eas- (Agnello et al., 1994). On other crops in the USA ily distinguished from non-dyed males that have as well as around the world, pheromone mon- been blown in on weather systems from southern itoring traps have asserted themselves in IPM desert valleys. programs as essential elements to the success The presence of a non-dyed male in a trap is of these programs. Their use is accepted as an assumed to be indicative of fertile, wild females integral and routine part of IPM. The chem- being present in the same area, and that the threat ical composition of thousands of pheromones of an increasing endemic population of pink boll- can be readily accessed on the websites “Pher- worms becoming established is real. Airdrops of obase” (www.pherobase.com) and “Pherolist” sterile moths are aimed at creating a ratio of (www.nysaes.cornell.edu/pheronet/). Many com- at least 60 : 1 pink : normal-colored (sterile : wild) paniescanbeaccessedonthewebthatprovide male captures in the pheromone traps. When the pheromone monitoring trap kits for hundreds of 60 : 1 ratio cannot be attained, either by too many pests. wild males present or too few sterile individuals being produced at a particular time by the sterile moth-rearing facility, the CDFA then applies 21.2 Detection and survey pheromone mating disruption. Monitoring and sanitation of this exotic pest under this program programs for invasive species has provided a significant savings to growers and to the environment, allowing cotton to continue Pheromone traps have played a large role in to be grown in central California with minimal detecting influxes of adult pest species from one insecticide load and maximum profits. region to another and also even from non-crop areas into crop areas. Survey programs involving grids of pheromone traps are used so routinely to report and track the yearly arrival of migrat- 21.3 Mass trapping ing adult populations of insects such as the black cutworm (Agrotis ipsilon) in the Midwest (Showers The once-discounted technique of mass trapping et al. 1989a, b) or the spread of expanding popu- using either male-produced or female-produced lations such as the gypsy moth (Lymantria dispar) pheromones has become a newly appreciated, (Elkinton & Cardé, 1981) that it has become an highly effective, environmentally friendly and rel- essential part of our arsenal of tools for tracking atively inexpensive means of suppressing popu- and ameliorating pest-movement-related threats. lations of certain pest species whose pheromone One example of a successful use of pheromone communication systems and bionomical charac- traps in detecting invasive species is the pink teristics make them susceptible to this approach. bollworm (Pectinophora gossypiella). Every summer In this technique after much experimentation, P1: aaa 9780521875950c21 cuuk358/Radcliffe ISBN: 978 0 521 87595 0 Top: 0.29637in Gutter: 0.79034in August 6, 2008 14:55 USE OF PHEROMONES IN IPM 275 Fig. 21.1 Incidence of American 25000 Normal Sanitation palm weevil-vectored red ring Normal A Sanitation RRD Palm Removal and disease in oil palms in Costa Rica, 20000 RRD Palm Trapping before and after mass trapping of Removal the weevils, as measured by the 15000 number of diseased trees that had to be removed each year from two 10000 plantations, A and B, from 1989 to 5000 1680 1575 632 2001. Plantation A comprised 6514 RRD palms removed 1587 893 1025 ha and Plantation B totaled 8719 ha. 0 From 1989 to 1992, before the 89 90 91 92 93 94 95 96 97 98 99 00 01 implementation of mass trapping of the weevils, disease incidence Year steadily rose. During this period only normal sanitation and diseased 12000 palm tree removal were used to try B to control the weevils. After 1992, Normal Normal Sanitation 10000 RRD Palm Removal and when pheromone mass trapping was Sanitation RRD Palm Trapping added to the program, the incidence 8000 Removal of red ring disease declined 6000 dramatically (from Oehlschlager et al., 2002). 4000 275 177 34 103 49 50 RRD palms removed 2000 0 89 90 91 92 93 94 95 96 97 98 99 00 01 Ye a r traps are deployed at densities on the crop plants liter bucket traps baited with the male-produced that have proven to attract and capture suffi- sex pheromone plus insecticide-laced sugarcane ciently large numbers of insects such that reduced (Chinchilla & Oehlschlager, 1992; Oehlschlager damage to the crop occurs. et al., 1992, 1993) were deployed at chest level One example of successful mass trapping using at a density of only one trap per 6.6 ha. The pheromone traps concerns the American palm results in the two plantations were virtually iden- weevil (Rhynchophorus palmarum). This species is a tical (Fig. 21.1). Before the mass-trapping pro- highly damaging pest of oil and coconut palms in gram was implemented, normal sanitation pro- Central and South America. A related species, R. cedures involving removal of red ring disease- ferrugineus, is a major pest of oil and other palms infected palms had failed to reduce the incidence in the Middle East. Larvae of R. palmarum cause of this disease. However, once mass trapping was direct damage when they bore into the trunks of added to the system, after one year the inci- the trees, but they also are a vector of red ring dis- dence of diseased trees needing to be removed ease, which is caused by a nematode, Rhadinaphe- dropped by nearly 80%, from about 10 000 diseased lenchus cocophilus.

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