Development of a Farm-Wide System for Control of Many of the Principal Lepidopterous Pests of Grapes and Tree Fruits Based on Disruption of Premating Pheromone Communication Between Male and Female Moths
1. Establish laboratory colonies for each Lepidoptera species to be tested.
2. Determine for each species the critical concentration of pheromone components needed to effectively disrupt premating communication of the following major lepidopterous pests of California stone fruit and grapes: Oriental fruitmoth (OFM), peach twigborer (PTB), omnivorous leafroller (OLR), raisin moth (RM), oblique-banded leafroller (OBLR) and orange tortrix (OT).
3. Perform quantitative analysis of various pheromone components, both alone and in mixtures to determine chemical stabilities in the absence of air, and volatilities when exposed to air.
4. Determine for each species the degree to which their specific pheromone components, presented separately or in mixtures, either enhance or interfere with the efficacy of communication disruption of other species when they are simultaneously exposed to marginally disruptive levels of their own pheromone components.
5. Demonstrate that appropriate combinations of the pheromone components representing each of the lepidopterous pests present in specified 160-acre blocks of grapes or stone fruit can be released together into the air from widely separated mechanical dispensers spaced on ¼-mile grids, providing effective communication disruption of each of the species.
6. Determine and demonstrate the efficacy of this ranch-wide communication disruption system, when it is maintained in 160-acre blocks through the entire effective pest season, by comparing reductions in larval infestations attacking the crop foliage, fruit and stems with reductions that are caused in comparison blocks by presently available commercial pheromone-disruption systems or by presently recommended pesticidal control methods.
7. Measure the edge effect of larval infestation of the respective pests that is caused by female moths that mate in nearby untreated areas and then fly into and lay eggs in the pheromone-protected area.
8. Arrange field days at the 160-acre treated ranches and publish results in newsletters and appropriate agricultural publications to inform interested growers, farm advisors, PCAs, and regulatory personnel at both state and federal levels with regard to the new technology.
A novel device for dispensing pheromones into the air of agricultural fields, for the purpose of communication disruption and elimination of mating of pest moth species, is the puffer. These machines release repeated puffs of pheromone from pressurized aerosol cans, with individual puffs often containing pheromone equivalent to millions of female moths. They have a number of advantages, in comparison to traditional hand-applied pheromone-release devices. Because the pheromone is protected from light and oxygen until the moment of release, chemical breakdown is minimized. Two or more pheromones can be mixed and emitted together, giving the opportunity to obtain simultaneous control of more than one species. The amount of pheromone is the same for the last puff as it is for the first puff released from the can, giving a predictable amount of pheromone delivered per unit of time. Labor costs for installing puffers are apt to be considerably lower than they are for hand-applied devices.
Nine large-acreage, season long trials were conducted during 1996, 1997 and 1998 to evaluate the puffer technique for management of lepidopterous pests on peaches and table grapes. Four trials on peaches were directed at simultaneous mating disruption and control of the oriental fruitmoth, omnivouous leafroller and the peach twigborer. Five trials on table grapes were directed at mating disruption of the omnivouous leafroller and raisin moth. In these trials, puffers showed high potential for controlling multiple pest species on a wide area, farm-wide basis.
Our work to date has been directed toward determining optimum pheromone blends and quantities that are needed in order to disrupt premating pheromone communication of OLR, OFM and PTB in peaches and OLR, OT and RM in table grapes. Early research phases were conducted in field plots with miniature pheromone evaporators. These were arrayed in 6 x 6-evaporator grids and separations between evaporators were varied to determine which combinations of these chemicals were best at preventing male moths from locating virgin females and synthetic lure bated traps.
In separate tests, we have evaluated the Sentry (formerly Ecogen) “coil” formulated for OLR, OT, PTB, OFM and RM pheromones when applied in vineyards and orchards at the rate of 130 and 260 coils per acre. Each application provided a total of 6.5 or 13 grams pheromone for the season. The OLR and OT provided effective communication disruption for these species for 120 days. OFM provided disruption for 60 days and PTB and RM both disrupted communication for 30 days at best.
A large amount of cross disruption of communication is encountered among the three leafroller species, OLR, OT and OBLR reflecting certain pheromone components that are identical in the pheromone blends of each of these species. This cross disruption of leafroller species stimulates our continued investigation into a possible generic pheromone blend for all leafroller species. No evidence for a lessening of communication disruption in any target species through simultaneous exposure to the pheromones has been detected.
We sample for larvae infestation to fruit in transects, with sampling rows extending from border to border through the center of the field. Through the use of this technique we have estimated that penetration of OLR mated females into a puffer treated block is only 20 meters. However our failure to disrupt OLR mating in the 40-acre block in 1997 and RM indicates some conditions moths of these species may penetrate into orchards and vineyards. After a more detailed literature search of RM pheromone it was discovered the total RM pheromone complex has never been fully researched. We have discussed this finding with other researchers and interested commodity groups who are in the process of finding the correct pheromone complex.
We have been interviewed on 17 occasions by farm magazines and newspapers, one radio station and one television station in 1996, 1997 and 1998. The stories have raised interest in growers about puffers and their potential use in moth communication disruption. We have participated in fourteen grower-oriented conferences to an audience of over 1,000 growers, PCA’s and regulatory people.
Ultimately puffers will be comparable to or less expensive than other means of disseminating pheromones in orchards and vineyards. Individual puffers will cost $40 and will last 5 years. Because puffers are used at great separations in the field the cost of placement and maintenance is low. One man can place puffers around a 40-acre block in about three hours. The major expense will be the pheromone chemicals, which the price will be reduced as the usage is increased.
At the end of the three-year project the system is ready for a limited commercialization with a doubling of potential users each year. As registrations become available and use increases the ultimate cost of this system will decrease.
Because Lepidoptera often represent the key pests of a crop, the ability to withhold hard pesticides applications has obvious benefits. Fewer broad-spectrum pesticides treatments enable the establishment of biological controls and free the grower from reliance on pesticides. With fewer pesticide treatments a resurgence of beneficial insects is likely and pesticide resistance is reduced. The implementation of a puffer pheromone disruption system can reduce two or three pesticide applications of Imidan and Lannate each year.
Farmer Adoption and Direct Impact
Registration for the pheromone chemicals to be used in puffers has been applied for. Once the chemicals are registered as pheromone by their manufactures then the chemicals can be registered for use in the aerosol puffer system. For some of these chemicals it may be the year 2000 or later.
This summary was prepared by the project coordinator for the 1999 reporting cycle.