Liquid Baits Control Argentine Ants Sustainably in Coastal Vineyards

California Agriculture

Volume 62, Number 4 2008 Page 177

Liquid baits control Argentine ants sustainably in coastal vineyards

Monica L. Cooper Kent M. Daane Erik H. Nelson Lucia G. Varela Mark Battany Neil D. Tsutsui M K. Rust

Copyright c 2008 by Regents of the University of California, unless otherwise noted. This article is part of the collected publications of California Agriculture. California Agriculture is archived by the eScholarship Repository of the California Digital Library. Abstract

Liquid ant baits are an alternative to broad-spectrum insecticide sprays conventionally used to control Argentine ants. We review the development of liquid ant baits, which capitalize on the ants’ sugar-feeding requirements and social structure to deliver small doses of toxicant throughout the colony. The ant bait program described here, developed for commercial vineyards, also has the potential to facilitate the use of biological controls for mealybug and scale pests. The implementation of an Argentine ant bait program will enable grape growers to target other pests more selectively with insecticides, further contributing to their sustainable viticulture practices.

Keywords: Argentine ants, liquid baits, sustainable management

Suggested Citation: Monica L. Cooper, Kent M. Daane, Erik H. Nelson, Lucia G. Varela, Mark Battany, Neil D. Tsutsui, and M K. Rust (2008) “Liquid baits control Argentine ants sustainably in coastal vineyards”, California Agriculture: Vol. 62: No. 4, Page 177. http://repositories.cdlib.org/anrcs/californiaagriculture/v62/n4/p177 REVIEW ARTICLE ▼ Liquid baits control Argentine ants sustainably in coastal vineyards

by Monica L. Cooper, Kent M. Daane, Erik H. Nelson, Lucia G. Varela, Mark C. Battany, Wild Alex Neil D. Tsutsui and Michael K. Rust

Liquid ant baits are an alternative to broad-spectrum insecticide sprays conventionally used to control Argentine ants. We review the development of liquid ant baits, which capitalize on the ants’ sugar- feeding requirements and social structure to deliver small doses of toxicant throughout the colony. The ant bait program described here, developed for commercial vineyards, also has the potential to facilitate the use of biological controls for mealybug and scale pests. The implementation of an Argentine ant bait program will enable grape growers to target other pests more selectively with insecticides, further contributing to their sustainable An Argentine ant tends an adult mealybug. A drop of honeydew, the sugar-rich viticulture practices. mealybug excretion, can be seen in the ant’s mouthparts.

he Argentine ant is an invasive pest grape mealybug (Pseudococcus maritimus out the colony. We also discuss future that has spread throughout Cali- [Ehrhorn]), obscure mealybug (P. viburni avenues of study to further control forniaT since it was fi rst reported from [Signoret]) (Daane et al. 2007; Phillips Argentine ant populations. Ontario, Calif., in 1905. Though popu- and Sherk 1991) and vine mealybug Argentine ant biology larly recognized as a household pest (Planococcus fi cus [Signoret]), a particu- (Vega and Rust 2001), the Argentine ant larly severe pest that recently invaded In agricultural systems, Argentine (Linepithema humile [Mayr]) also causes California (Daane, Bentley, et al. 2006). ants are most commonly found in areas severe problems in natural systems by Mealybug feeding may partially defoli- with disturbed habitats and some soil displacing native ants and other insect ate vines, and crop damage results when moisture. Their nests are composed of species, and even some vertebrate and mealybugs infest bunches and excrete reproductive females (queens), sterile plant populations (Holway et al. 2002). honeydew, which promotes the growth females (workers), winged reproductive In addition, in agricultural systems the of sooty molds and bunch rots (Godfrey males and immature ants (eggs, larvae Argentine ant is associated with out- et al. 2002). Mealybugs also indirectly and pupae). Outside the species’ native breaks of phloem-feeding insects such damage vines by vectoring leafroll vi- range, the social structure and biology as mealybugs, scale and aphids, which ruses (Golino et al. 1999) (see page 156). of the Argentine ant have increased the ants protect from natural enemies; To reduce vineyard damage from its pest status. In its introduced range, in exchange, the ants collect the sugar- mealybugs and promote their biologi- Argentine ant nests are unicolonial, form- rich food source (honeydew) excreted cal control (see page 167), the Argentine ing massive “supercolonies” character- by the phloem-feeders (Buckley and ant must be suppressed. We review the ized by the absence of aggression among Gullan 1991). development of liquid ant baits, which workers across large geographic areas In California vineyards, the capitalize on the ants’ sugar-feeding (Tsutsui et al. 2000). The main European Argentine ant has been implicated in requirements and social structure to supercolony has been reported to extend outbreaks of three mealybugs species: deliver small doses of toxicant through- up to 3,700 miles (6,000 kilometers), en-

http://CaliforniaAgriculture.ucop.edu • OctOBER–DEcEMBER 2008 177 sprays targeted at ants may disrupt represents no mealybugs; “1” represents

Alex Wild Alex integrated pest management (IPM) 1 to 10 mealybugs and/or honeydew; programs by suppressing populations “2” represents more than 10 mealybugs, of beneficial insects. While these sprays sooty mold and/or honeydew; and “3” may also kill foraging ants, unlike baits represents heavily infested, unmarket- they have little effect on ants in nests able clusters. and so allow for an eventual resurgence Because most insecticides are not of the population (Klotz et al. 2002; Rust highly soluble in water, one of the major et al. 1996). challenges facing the study group was to find suitable toxicants that can be for- Developing liquid baits mulated into sugar water solutions. The Ant control in vineyards has been in- first vineyard trials were in 2000 and vestigated using granular protein baits 2001, and compared a no-bait control to for Formica species (Klotz et al. 2003; four liquid bait treatments: boric acid Argentine ants are aggressive and social. Above, Tollerup et al. 2004) and liquid sugar (0.5%), imidacloprid (0.0001%), fipronil three Argentine ants attack the native harvester baits for Argentine ants (Daane, Sime, (0.0001%) and thiamethoxam (0.0001%). ant (Pogonomyrmex subdentatus) en masse. et al. 2006; Daane et al. 2008; Nelson These initial trials showed little differ- and Daane 2007). The liquid bait trials ence between the no-bait control and compassing millions of nests and com- discussed here were conducted either the liquid bait treatments. prising billions of workers (Giraud et al. in Central Coast vineyards (San Luis However, valuable lessons were 2002). In the absence of aggression and Obispo, Santa Barbara and Monterey learned and applied to subsequent tri- territoriality, more resources can be di- counties) populated with obscure als, in which measurable differences rected to colony growth, the domination mealybug, or in North Coast vineyards were recorded among treatments of food and nesting resources, and the (Napa and Sonoma counties) populated (Daane, Sime, et al. 2006). First, bait sta- displacement of native ants in direct, ag- with grape mealybug. The initial liquid tions left in the field for longer than 3 gressive encounters (Holway et al. 1998). bait trials were conducted from 2000 to weeks, without the addition of preser- However, the ants’ biology can also 2002, based on methodologies devel- vative, fouled as the sugar fermented. be used against them. The Argentine oped for urban systems by Klotz et al. Second, unlike the urban systems ant diet is composed mainly of carbohy- (2002) and described in detail by Daane, tested, the vineyards had incredibly drates (sugars) in a liquid form, such as Sime, et al. (2006). large Argentine ant populations: up to honeydew (Rust et al. 2000). Therefore, In brief, the liquid baits were com- 1.2 ounces (35 grams) of sugar water while granular protein baits are not heav- posed of 25% sugar water laced with a per day were removed from monitor- ily foraged by Argentine ant workers, small dose of one of four different toxi- ing tubes, the equivalent of more than sugar water laced with insecticide is an cants, and were deployed in approxi- 100,000 ant visits! excellent method for delivering small but mately 250- to 500-milliliter containers In a later trial in 2002, researchers lethal amounts of toxicant to the colony placed on the ground or attached to refilled and cleaned the bait stations (Silverman and Roulston 2001). Liquid the vine trunk. Treatments were rep- every 2 weeks to reduce bait fermenta- baits exploit the social behavior of ants licated four to six times in large ex- tion, increased the distance between to distribute toxicant to colony members, perimental plots ranging from 0.25 to including larvae and queens (Silverman 0.5 acre (0.1 to 0.2 hectare) to account The ants’ biology can be and Roulston 2003). Argentine ants also for the movement of Argentine ants, used against them. use persistent trail pheromones to recruit which forage up to 150 feet from their colony members to food resources, result- nests (Ripa et al. 1999). ing in fidelity to bait-station locations Ant feeding activity was used to plots to keep the large ant population (Aron et al. 1989; Vega and Rust 2001). quantify ant densities and was based on from spilling over between treatment Because bait is exchanged among colony the amount of nontoxic sugar water ants plots, and increased the number of bait members via trophallaxis (i.e., ants feed- removed from 50-milliliter plastic tubes stations deployed from 35 per acre (85 ing other ants), baits have the potential (monitoring tubes). Sugar-water removal per hectare) to 65 to 250 per acre (160 to affect the nest population and provide rates are related to ant density because to 620 per hectare). The researchers season-long control (Forschler and Evans each milliliter removed represents ap- also used only one bait formulation 1994; Klotz et al. 2006). proximately 3,300 ant visits to the moni- (0.0001% thiamethoxam) and deployed Liquid baits reduce undesirable toring tube (Greenberg et al. 2006). bait stations earlier in the season to environmental impacts because they Mealybug densities were assessed take advantage of spring foraging require a relatively small amount of using 2.5-to-3-minute visual searches of activity. With these changes, research- insecticide, and the dispenser design randomly selected vines (timed counts), ers recorded significant differences can minimize insecticide delivery to based on methodologies developed by in Argentine ant feeding activity and nontarget insects including predators Geiger and Daane (2001). Near harvest, mealybug crop damage between the and pollinators (Taniguchi et al. 2005). crop damage was measured by rating bait and no-bait treatments with the In contrast, broad-spectrum insecticide fruit clusters on a scale from 0 to 3: “0” liquid bait treatment (fig. 1).

178 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 125 25 A A Imidacloprid 100 20 Thiamethoxam

75 15 Boric acid Liquid bait Control 50 Control 10

25 5 Ant visits (x 1,000) tube/day Ant visits (x 1,000) tube/day 0 Apr May Jun Jul Aug Sept Oct Nov Dec 0 Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec 600 a b b ab a c B 100 500 B 80 400 Damage None 60 Damage 300 Low None 40 200 Moderate Low Severe

Clusters rated (no.) Moderate 20 Clusters rated (no.) 100 Severe

0 0 Liquid bait Control Imidacloprid Thiamethoxam Boric acid Control

Fig. 1. Comparison of liquid ant bait (0.0001% thiamethoxam in Fig. 2. Comparison of liquid ant baits with different toxicants and a no- 25% sugar water) and no-bait control in a North Coast vineyard bait control in a Central Coast vineyard for (A) ant visits to monitoring for (A) ant visits to monitoring tubes (F = 28.981, df = 1,6, P = tubes and (B) crop damage as rated on Oct. 14, 2003 (letters above 0.002) and (B) crop damage as rated Sept. 17–19, 2002 (Pearson’s each treatment bar indicate a significant difference using pairwise χ2 = 44.72, df = 3, P < 0.001). Source: Daane, Sime, et al. 2006. comparisons for Pearson’s chi-square test). Source: Daane et al. 2008, where complete statistical description is provided.

The poor results with imidacloprid spinosad (0.015%) and a liquid bait Evaluating toxicants were attributed to rapid photodegrada- containing spinosad (0.015%) (Daane Results from the 2002 trial showed tion of this toxicant and to the low con- et al. 2008). Researchers used meth- that liquid baits could, in principle, be centration of active ingredient. Because odologies similar to those described used to lower Argentine ant densities the imidacloprid concentration in the previously, except that the bait sta- (Daane, Sime, et al. 2006). However, in bait (0.0001%) was below the reported, tions were shielded from light with practice grower adoption would require delayed toxicity range (0.00071% to Styrofoam containers to protect answers to the following critical ques- 0.0092%) (Rust et al. 2004), it may have against degradation of the toxicants. tions: What toxicant would be used, and killed some foraging ants, but did not Results again demonstrated the sup- would it be available as a commercial have the desired colonywide impact. pressive impact that liquid baits have formulation? What bait station could The formulation of liquid baits can on Argentine ant and mealybug popu- be used? How many bait stations are be tricky: the concentration of active in- lations (fig. 3). Granular spinosad bait needed per acre? At what time of year gredient must be great enough to cause had no impact on ant populations, should baiting begin, and should bait be ant mortality yet low enough to be while both the spinosad and imidaclo- deployed continuously or seasonally? slow-acting (killing ants in 1 to 4 days), prid liquid baits significantly lowered Using the improved bait-station de- allowing ample time for bait to spread ant densities. This result reaffirmed ployment methods, researchers reevalu- throughout the colony and remain at- the need for a liquid sugary bait to ated different toxicants by testing the tractive to foraging ants (Rust et al. target the Argentine ant rather than a impact of liquid baits containing either 2004). The range of suitable concentra- granular protein bait (Aron et al. 2001; boric acid (0.5%), imidacloprid (0.0001%) tions for a variety of toxicants has been Rust et al. 2000). or thiamethoxam (0.0001%) against a delineated in laboratory trials, and baits As a result of this research, several no-bait control (Daane et al. 2008). As with toxicant levels within these ranges liquid ant-bait products are now avail- before, large plots were located in com- are referred to as having delayed toxic- able for use in agricultural systems, mercial vineyards, and liquid baits were ity (Hooper-Bui and Rust 2000; Klotz et and others may become available in delivered in plastic containers deployed al. 2000; Rust et al. 2004). the future. The registered products at about 50 per acre (160 per hectare). include Vitis (imidacloprid, Bayer Commercial bait products Results showed that the thiamethoxam CropScience), Gourmet Liquid Ant and boric acid treatments consistently The next phase of the bait program Bait (borate, Innovative Pest Control and significantly reduced ant feeding was to test commercially formulated Products) and Tango (methoprene, activity measured by monitoring tubes, bait products, including a liquid bait Wellmark International). During the mealybug density measured by timed containing imidacloprid (0.005%), 2007 season growers began using these counts and fruit damage ratings (fig. 2). a granular protein bait containing products in commercial vineyards and

http://CaliforniaAgriculture.ucop.edu • October–December 2008 179 orchards in five California counties, independent of research activities. Ongoing efficacy trials will determine the long-term impacts of these baits on Argentine ant populations (Cooper and Daane, unpublished data). Liquid ant-bait stations registered for use in vineyards and orchards by the ChemSAC arm of the U.S. EPA (fall 2005) include the UC-designed PVC station, left and center, with bait reservoir, Bait-station design and, right, the KM AntPro station (www.kmantpro.com). A commercially acceptable bait station for vineyards should protect the protective PVC housing and an inner investigated bait densities will provide bait from degradation, be easily moved disposable bait bottle, has been used in some reduction in ant activity and mealy- but sturdy, be relatively inexpensive large-scale commercial vineyard trials bug damage. This work implies that the or long-lasting, and hold enough bait since 2004. Both bait stations were ap- optimal bait-station density may depend so that it must be filled only once per proved in 2005 for use in vineyards and on the size of the local Argentine ant season, provided the bait is formulated orchards by the ChemSAC arm of the population. Higher densities may be re- with preservative to prevent spoilage. U.S. Environmental Protection Agency. quired to achieve measurable ant control The KM AntPro dispenser consists of a within one or two seasons, particularly Densities for effective control central reservoir that slowly releases bait in vineyards with higher ant densities. In in response to ant feeding. It has been In urban systems, researchers subsequent seasons, as the ant population used successfully in Argentine ant tri- were able to affect the relatively small declines, continued suppression may be als in citrus orchards (Greenberg et al. Argentine ant populations by placing achieved with fewer bait stations per acre. 2006). A bait station developed by UC stations at very low densities (Klotz et The optimal bait-station density is researchers, which consists of an outer al. 2006). In vineyards, however, bait determined in part by the distance that stations were deployed ants travel from the nest to locate food. at much higher densities Foraging distance has been investigated Liquid imidacloprid 35 to produce measurable for Argentine ants in urban environ- A Liquid spinosad 30 Granular spinosad effects on ant popula- ments (Vega and Rust 2003) and citrus 25 Control tions (Daane, Sime, et groves (Ripa et al. 1999). Sugar water 20 al. 2006). To determine labeled with rabbit immunoglobin G

15 how many bait stations protein was used to study ant move- are needed, Nelson and ment in vineyards (Daane, Cooper, et al. 10 Daane (2007) compared 2006). The percentage of ants carrying 5 a range of densities (0 to protein-labeled sugar water, as deter-

Ant visits (x 1,000) tube/day 0 91 per acre, or up to 225 mined by a sandwich enzyme-linked

Mar Apr May Jun Jul Aug Sept Oct Nov per hectare) in commer- immunosorbent assay (ELISA), declined cial vineyards, and mea- sharply as distance from the bait sta- a ab b b 100 sured the impact on ant tion increased (fig. 5). In the 6 days fol- B density and mealybug lowing the placement of sugar water 80 fruit-infestation levels. in the field, most bait movement was Damage The results showed limited to within 66 feet (20 meters) of 60 None that incremental in- the stations; beyond 66 feet, fewer than Low 40 Moderate creases in bait-station 10% of the ants were carrying the bait. Severe density had an increas- However, a few ants at the most distant 20 Clusters rated (no.) ingly suppressive effect sample points did test positive, showing 0 on both ant activity and that ants occasionally carried the sugar Liquid Liquid Granular Control imidacloprid spinosad spinosad mealybug abundance water more than 236 feet (72 meters). in fruit clusters (fig. 4). Bait movement appears to be highly Fig. 3. Comparison of ant baits with different commercial baits However, the data did localized in the first 6 days after a bait and a no-bait control in a North Coast vineyard for (A) ant visits not indicate a particular station is placed. to monitoring tubes and (B) crop damage as rated on Aug. 16, bait density that maxi- We expected trellising along rows 2004 (letters above each treatment bar indicate a significant difference using pairwise comparisons for Pearson’s chi-square mized ant or mealybug to facilitate bait movement, and row test). Source: Daane et al. 2008, where complete statistical suppression. Rather, the middles to impede bait movement. description is provided. results suggest that all But surprisingly, the movement of bait

180 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 12 100 A (vines) 10 90

8 80 6 70 Ant foraging distance 4 Across rows 2 60 Along rows Average mealybug/vine/sample Average 0 50 0 10 20 30 40 50 60 70 80 90 30 B (fruit clusters) 40 25 30 20 Ants testing positive for lgG (%) 15 20

10 10 5 Average mealybugs/cluster Average 0 0 0 25 50 75 100 125 150 175 200 225 0 10 20 30 40 50 60 70 80 90 Distance from bait station (ft) Bait stations/acre

Fig. 5. Movement by Argentine ant of sugar water labeled with Fig. 4. Bait-station density and grape mealybug abundance (A) on rabbit protein (IgG) collected 6 days following initiation of treatment; vines during the growing season and (B) in fruit clusters at harvest, y-axis shows proportion of ants that tested positive for the rabbit showing a significant negative relationship. Bait stations were protein. Data are averages of four plots in a Sonoma County vineyard. deployed at 0 to 78 stations per acre. Source: Nelson and Daane 2007. Movement across and along rows was not significantly different. across vineyard rows was similar to vae. This period is considered essential resources such as mealybug honeydew movement along rows. This result sug- to decreasing the effective mating pop- and ripening grapes in the vineyard. gests that bait stations do not need to be ulation. Although worker larvae con- This foraging shift toward alterna- placed in every row, but may be placed tinue to populate the nest from July to tive food resources reflects typical in every second or third row. September, ant foraging activity at bait Argentine ant behavior in agricultural stations and monitoring tubes declines settings and has been well documented Timing and duration during this time (figs. 1, 3), due in part in citrus groves, where the number Liquid baits target Argentine ant to the prevalence of alternative food of aphids and scale insects tended by larvae and therefore, should be deployed during periods of peak larval development and active nest expan- Wild Alex sion. To delineate these periods, Argentine ant nests were collected monthly from April 2004 to May 2006 at a vineyard in San Luis Obispo County. Using a flotation method, dead ants were separated from small batches of nest soil (1.8 to 3.5 ounces, or 50 to 100 grams) and then categorized into eight recognized life stages: egg, worker larva, worker pupa and sterile adult worker; and reproductive larva, reproductive pupa, male and queen. This study found that Argentine ant reproductive larvae are most numer- ous in April, and that worker larvae are present virtually yearround (fig. 6). Therefore, bait deployed during April and May has the greatest potential to affect colony development and expan- sion by targeting the reproductive lar- An Argentine ant nest in northern Argentina shows various life stages: egg, larva, pupa and adult.

http://CaliforniaAgriculture.ucop.edu • October–December 2008 181 spring to target developing larvae — especially those that will become new queens and males — and to coincide with a period of active foraging by ant workers. Ongoing trials investigating the impact of various bait-deployment periods will further elucidate the links between timing and duration of bait deployment as it affects Argentine ant and mealybug populations. Future directions Grape growers now have at their disposal a sustainable Argentine ant management tool that is an alternative Above, mealybug parasitoids are released in or companion to broad-spectrum in- experimental plots with ant bait programs. secticides. The registered bait products Right, a plastic centrifuge tube is filled with 50 and stations that arose from this work milliliters of 25% sugar water to monitor ant populations in vineyard trials. One milliliter of allowed growers to begin implement- liquid removed is equivalent to roughly 3,300 ing this program on a commercial ant visits to the tube. scale in 2007. Continuing research on the density and timing of bait-station Argentine ants increases dramatically constrict their range in the winter deployment has the potential to im- from June to October (Horton 1918; months (Markin et al. 1970) in response prove the program’s effectiveness Newell and Barber 1913). Warm weather to cool, wet weather. Therefore, foraging and lower costs, thereby facilitating and favorable foraging conditions af- from November to March is extremely broader implementation. ter harvest result in a second, shorter, light due to these climatic factors and Concurrently, the expanded produc- intensive foraging period (figs. 1, 3) in because there are fewer larvae in the tion and release of natural enemies October, which may also be exploited, nest during this time. will provide better biological control with toxic bait affecting the remain- These results suggest that to have of vineyard mealybugs. Ongoing stud- ing larvae and the overwintering adult the maximum impact on ant popula- ies are evaluating the impact of the population. Argentine ants typically tions, baits should be deployed in early Argentine ant on developing parasitoids, as well as delineating the mealybug’s production cycles of honeydew Adult queen Reproductive pupae Adult workers Worker larvae and attractiveness to tending ants. Adult males Reproductive larvae Worker pupae Future studies in vineyard landscapes 100 where Argentine ant populations are declining in response to bait treatments will examine impacts on the distribu- tion patterns of nontarget ants. Also, 75 data reported here was collected in fields populated with either grape or obscure mealybug; the program has since been expanded to include work in 50 fields populated with the invasive vine mealybug and European fruit lecanium scale, Parthenolecanium corni (Bouché). In the future, the methods described 25 here may be supplemented by the use of semiochemicals, including pheromones, allomones, kairomones, attractants and

Nest population collected in different life stages (%) Nest population collected in different repellents that modify ant behavior. 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec For example, trail pheromones or other chemical attractants could be used to Fig. 6. Argentine ant life cycle in coastal California vineyards, based on averaged data enhance recruitment to bait (Greenberg from nest collections in a San Luis Obispo County vineyard, 2004–2006. Data presented as and Klotz 2000) or to permit the use percentage of nest population in recognized life stages. of fewer bait stations in a given area.

182 CALIFORNIA AGRICULTURE • VOLUME 62, NUMBER 4 Alternatively, studies focusing on the disrupted by the presence of Argentine Program and UC Cooperative Extension (UCCE) chemical ecology of the Argentine ant ants. Ultimately, this program has the Sonoma County; M.C. Battany is Farm Advisor, UCCE San Luis Obispo County; N.D. Tsutsui is As- may reveal methods for disrupting potential to minimize the use of broad- sistant Professor, Department of Environmental their foraging or inducing aggression spectrum chemicals and facilitate the Science, Policy and Management, UC Berkeley; and among nest mates. These newly explored use of sustainable and IPM practices. M.K. Rust is Professor, Department of Entomology, control methods, combined with the UC Riverside. We thank California Department of liquid baits described here, hold prom- Food and Agriculture for funding this review; and ise for advancing IPM strategies for the the America Vineyard Foundation, California Table M.L. Cooper is Staff Research Associate, Grape Commission, California Raisin Marketing Argentine ant in managed ecosystems. K.M. Daane is Cooperative Extension Specialist, Board, Viticulture Consortium and Central Coast In a broader sense, the ant management and E.H. Nelson is Postdoctoral Researcher, Depart- Vineyard Team for funding this research. We grate- system developed and tested in vine- ment of Environmental Science, Policy and Man- fully acknowledge the cooperation of growers in yards can be applied to other managed agement, UC Berkeley; L.G. Varela is Integrated Monterey, Napa, San Luis Obispo, Santa Barbara and natural ecosystems that have been Pest Management (IPM) Advisor, UC Statewide IPM and Sonoma counties.

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