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Funded Project |
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Funding Program:
Regional IPM Competitive Grants - Northeastern |
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Project Title:
Development of IPM Methods for Oriental Beetle Management in Multiple Crops |
Project Directors (PDs):
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Lead State: NJ Lead Organization: Rutgers University |
| Research Funding: $99,678 |
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Start Date: Sep-01-2001 End Date: Aug-31-2004 |
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Pests Involved: oriental beetles |
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Site/Commodity: turf, turfgrasses, blueberry, blueberries, nursery |
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Area of Emphasis: biocontrol, biological control, traps, nematodes |
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Summary:
The Oriental beetle has become a major pest of turfgrass, nursery stock, greenhouse ornamental crops, and blueberries in southeastern New York, New Jersey, Rhode Island and Connecticut. In addition, it is also known to infest cranberries, raspberries, strawberries, peaches, and sweet potatoes in this region. Within these systems, the Japanese beetle is considered the key pest species and has received much of the research attention even though a significant amount of the damage attributed to this species in the Northeast is actually caused by the Oriental beetle, Exomala orientalis (Waterhouse). The minor pest status often attributed to Oriental beetle is largely because adults are cryptic, and the larvae of Japanese and Oriental beetles are indistinguishable without magnification. In fact, larvae of the two species occur in mixed populations throughout most of their common area of distribution (Vittum et al. 1999), and in southeastern New York, New Jersey, and southern New England, the Oriental beetle has become the dominating white grub species (AMK, JHL, and SP, personal observations; R. Cowles, personal communication).
We propose to develop novel IPM methods for Oriental beetle management in three of these affected systems, turfgrass, nursery stock, and blueberries. These methods will comprise the whole spectrum from preventative to curative control including improved predictability of Oriental beetle outbreaks. We will develop mating disruption technology using sprayable, microencapsulated formulation and high-release widely spaced macrodispenser systems that can be used in a preventative approach. We will establish relationships between pheromone trap captures and larval density in the following generation that will help predict Oriental beetle outbreaks. Finally, we will develop effective and environmentally sound curative control options based on new highly pathogenic entomopathogenic nematode isolates and the synergistic combination of these nematodes with low-impact insecticides. If successful, this project will provide additional tools that can be easily integrated in to current IPM programs in turfgrass, blueberries, and nursery crops. Based on the relationship between pheromone trap captures and grub density in the following generation, we will be able to delineate Oriental beetle outbreak populations and thereby reduce the prophylactic applications of insecticides where significant populations do not exist. The ability to identify Oriental beetle infestations even at low densities will save time by limiting the need for time consuming examination of roots. Cost comparisons of monitoring with pheromone traps and traditional methods will be made. The use of pheromone traps in identifying infestations will also prevent the export of infested rootstock to uninfested areas. The availability of alternative low-risk Oriental beetle management strategies such as mating disruption, entomopathogenic nematodes, and nematode-insecticide combinations will enhance environmental quality and reduce our reliance on organophosphate insecticides. Observations on nematode-insecticide synergy for Oriental beetle will also have implications for the control of other white grub species especially Japanese beetle. The cost of managing Oriental beetle with mating disruption, entomopathogenic nematodes, and nematode-synergist combinations will be compared with traditional treatment tactics. Considering that the three Principal Investigators are primarily responsible for research and training of extension professionals serving blueberries, nursery crops, and turfgrass systems, there is a high degree of probability that technology developed under this proposal will be transferred to relevant clientele in New Jersey and throughout the Northeast. PROBLEM, BACKGROUND, AND JUSTIFICATION INTRODUCTION: In the northeastern United States, landscape and horticultural plants, and agronomic crops are subject to intense feeding pressure from a complex of scarab species. Within this complex, the Japanese beetle is considered the key pest species and has received much of the research attention even though a significant amount of the damage attributed to this species in the Northeast is actually caused by the Oriental beetle, Exomala orientalis (Waterhouse), which is the focus of this proposal. The Oriental beetle has been erroneously considered a relatively minor pest until recently because adults are cryptic and largely go unnoticed and the larvae of Japanese and Oriental beetle are indistinguishable without magnification. In fact, larvae of the two species occur in mixed populations throughout most of their common area of distribution (Vittum et al. 1999), and in southeastern New York, New Jersey, and southern New England, the Oriental beetle has become the dominating white grub species (AMK, JHL, and SP, personal observations; R. Cowles, personal communication). The Oriental beetle, which is probably a native of Japan, was introduced to the Hawaiian island of Oahu around 1908, where it became a serious pest of sugarcane (Alm et al. 1995). On the US mainland, the Oriental beetle was first collected in 1920 in a New Haven, Connecticut, nursery where it was presumably imported from Japan in infested balled nursery stock (Vittum et al. 1999). The Oriental beetle has been reported in all coastal New England and Middle Atlantic States as well as Ohio, Virginia, North Carolina, South Carolina, West Virginia, Tennessee and Hawaii (Alm et al., 1999). The root feeding of the Oriental beetle larvae can result in complete destruction of the root system and death of host plant, especially when larval populations are high. The transport of infested nursery stock has the potential to spread this insect to uninfested areas in United States and Canada. The Oriental beetle has become the most important pest of turfgrass, nursery stock, greenhouse ornamental crops, blueberries, cranberries, raspberries, strawberries, peaches, and sweet potatoes, in the Long Island region of New York State, New Jersey, Rhode Island and Connecticut (Alm et al., 1999; AMK, JHL, and SP, personal observations). We propose to develop IPM methods for Oriental beetle management in three of these affected systems, turfgrass, nursery stock, and blueberries. Our methods, however, will also be applicable in other systems. Turfgrass comprises a variety of grass species grown as a permanent or semi-permanent managed ground cover under a range of management systems (e.g., lawns, parks, cemeteries, sod farms, golf courses, athletic fields) covering > 30 million acres in the United States (Potter 1998). In its many forms, is estimated to be a $45 billion industry in the United States (Potter 1998). In New Jersey alone, there are > 870,000 acres of turfgrass, including 2 million home lawns, 250 golf courses, and 27 sod farms. With annual revenues of > $700 million, turfgrass represents a significant component of New Jersey's economy. Turfgrass is often the most intensively managed planting in the urban landscape. Although there are large variations in value, input, demands, and damage thresholds between systems, tolerances for pests are generally low, resulting in frequent pesticide applications. In the Northeast, a complex of white grubs are the most widespread and difficult to control turfgrass insect pests. The Oriental beetle has become the dominating species in turfgrass in southeastern New York, New Jersey, and southern New England. In a recent survey in New Jersey we found the Oriental beetle to be the dominant species in 9 out of 10 turfgrass sites. Of the total 15,500 larvae collected, 70% were Oriental beetle, 15% Japanese beetle, and 10% Northern masked chafer, the remainder being Asiatic garden beetle and European chafer (Koppenhöfer, unpublished data). Despite the proximity of turf to people, especially children, and pets, chemical insecticides are still the primary tool for the management of white grubs and other turfgrass insect pests. The need for the development of alternatives is apparent. Nursery and greenhouse production is a multimillion-dollar industry and is the fastest growing segment of production agriculture in the United States. To serve their urban and suburban clientele, many nurseries and commercial greenhouses are located in close proximity to urban centers. Considering the impact of insecticide use in the urban environment, the importance of developing alternative strategies to manage Oriental beetles is apparent. New Jersey has a large and continually expanding nursery industry. In 1998, there were a total of 1,267 certified nurseries in New Jersey that accounted for over 14,000 acres in production. Most of this acreage is located in Monmouth, Burlington, Cumberland and Gloucester Counties. Nursery sales generate at least $200 million in sales annually. New Jersey nurseries present a highly diverse growing environment from field grown to the highly intensive pot-in-pot operations with the likelihood of hundreds of different types of plants grown at any one time and location. Azaleas, rhododendrons, arborvitae, juniper, daylilies are prominent species because they are among the most frequently requested plants by landscapers. Some individual potted ornamentals can reach values of $25/pot. No apparent host preference in perennial and/or woody ornamentals has been detected. A significant liability facing the nursery industry is the specter of interstate regulation for shipping infested material. The northeast region is facing difficulties from other regions when the nursery stock is found contaminated by Oriental beetle. Blueberries are a major component of the southern New Jersey economy with an annual value of about $35 million. Blueberries are grown in approximately 8,000 acres, mainly in the ecologically sensitive pine barrens of New Jersey. In recent years, outbreaks of soil insect pests have increased tremendously in blueberries, especially in the light, sandy-loam soils of Atlantic County (Polavarapu 1996a. These outbreaks are generally attributed to the waning effects of organochlorine insecticides that were used on blueberries until the early eighties. This problem is accentuated by the lack of soil insecticides registered for use in blueberries. Bushes that have sustained damage to the root system by grubs show reduced vigor, are twiggy, have smaller leaves, and support fewer berries than uninfested bushes of the same age. In a recent survey conducted to determine the species composition of scarab grubs infesting blueberries, we found that Oriental beetle was the dominant species in 13 of 15 blueberry fields sampled (57 to 100%). Of the total 2,591 grubs sampled, 90% were Oriental beetle grubs, the remainder being Asiatic garden beetle, Maladera castanea, and Japanese beetle (Polavarapu 1996a). DEVELOPMENT OF MONITORING AND MATING DISRUPTION METHODOLOGIES FOR ORIENTAL BEETLE MANAGEMENT: The sex pheromone of Oriental beetle consists of a 9:1 blend of (Z)-7-tetradecen-2-one and (E)-7-tetradecen-2-one (Zhang et al. 1994; Facundo et al. 1994). Field studies have indicated that at concentrations > 10 micrograms, (Z)-7-tetradecen-2-one alone was as effective as a 9:1 blend containing both (Z)-7-tetradecen-2-one and (E)-7-tetradecen-2-one (Facundo et al 1994). More recent work conducted at Rutgers (Polavarapu, Villani and Roelofs, unpublished) and in Rhode Island (Alm et al. 1999) has indicated that Trécé (Salinas, CA) Japanese beetle trap baited with red rubber septa at 300 µg concentration of (Z)-7-tetradecen-2-one alone is adequate to monitor adult flight of Oriental beetle. These rubber septa are now commercially available from IPM Technologies (Portland, Oregon) and other insect monitoring supply companies. Disruption of communication between opposite sexes by permeating the air with the sex pheromones has long been recognized as one of the most important applications of semiochemicals in pest management. Mating disruption with sex pheromones has been developed as an environmentally safe, non-toxic alternative to broad-spectrum insecticides for several insects (see Cardé and Minks 1995, for a review). Pest management programs based on mating disruption have been successfully developed and are commercially available for several lepidoptera including the pink bollworm (Staten et al. 1987), tomato pinworm (Trumble and Alvarado-Rodriguez 1993), oriental fruitmoth (Vickers et al. 1985), Codling moth, and grape berrymoth (Trimble 1993). However, mating disruption technology has not been shown to be effective for insects other than lepidoptera. Preliminary experiments conducted at Cornell University have indicated that application of the major component of Oriental beetle sex pheromone resulted in 64-90% reduction in trap catches in cages treated with the pheromone compared to catches in untreated cages (Facundo 1997). Based on these preliminary studies, we requested the 3M Canada Corporate Laboratories to synthesize the two ketone pheromone components and encapsulate for a slow release of the pheromone using their proprietary controlled-release delivery technology. Because Oriental beetles are known to spend most of their adult life near the soil surface locating the opposite sex, mating and ovipositing, our goal was to permeate the soil surface with the sex pheromones of this species. Sprayable pheromone formulation is especially suitable for this purpose because the soil matrix is a good medium to absorb/adsorb the pheromone and continuously release the pheromone overtime. We applied the encapsulated sprayable formulation at 40 g a.i./acre approximately at 9:1 ratio of Z:E components to one acre blueberry plots. There were three replicates. Three unsprayed one-acre plots served as controls. The pheromone was drenched in 300 gal/acre of water as 45-cm bands to both sides of the blueberry bushes. Four Pheromone traps baited with 300 µg of the (Z)-7-tetradecen-2-one were placed in all fields. (Z)-7-tetradecen-2-one alone at 40 g a.i/acre was evaluated in a nursery farm (mainly Rhododendrons and Azaleas). Pheromone formulation in nursery was broadcasted with a nursery sprayer using 300 gal/acre volume. The other protocols in the nursery were same as employed in blueberries. Pheromone trap catches in treated plots were 92-98% lower in treated plots following the application of the pheromone, indicating communication disruption between males and females (Fig. 1). Four weeks after the single pheromone application, only a small number of beetles continue to be trapped in the treated fields in both blueberries and nursery. Application of the major component alone appears to be sufficient to disrupt communication in this species (Fig. 1B). These initial data are very promising and worthy of further evaluation of the potential of the sex pheromone in disrupting mating of Oriental beetle. Fig. 1. Evaluation of (Z)-7-tetradecen-2-one and (E)-7-tetradecen-2-one in A) blueberries, and B) nursery. Arrows indicate the date of pheromone application. Recently we were advised by USEPA that (Z)-7-tetradecen-2-one, being a ketone, does not qualify for tolerance exemptions allowed for lepidopteran pheromones that end in alcohol, acetate, or aldehyde moieties. This means that large scale testing of the sprayable ketone pheromone is not feasible in food crops (blueberries) without resorting to crop destruction. Considering the large plots required for mating disruption trials, it is cost prohibitive to pay for crop destruction at this time. This prompted us to explore other pheromone dispensing technologies that are exempted by EPA from tolerance requirements. We identified the macrodispensers produced by Chem Tica Internacional S. A., San Jose, Costa Rica (Dr. Cam Oehlschlager) as one possibility. The dispensers produced by this company are unique in that they release extremely high rates of pheromone from a reservoir covered by a proprietary film (polymer). Because of the extremely high release rates, the number of dispensers required per ha for this technology is about the lowest per unit area compared to other retrievable dispensers that are currently used in tree fruits. During the 2000 season, we compared the efficacy of these widely spaced macrodispensers at a rate of 25 dispensers per ha with sprayable pheromone on one ha field grown nursery plots. Each dispenser was loaded with 3 g of the major component, for a total of 75 g a.i. /ha. Sprayable pheromone at the rate of 37.5 g a.i./ha was applied twice at 15-day interval for a total of 75 g a.i./ha. There were three replications. We also placed potted nursery plants (10 plants per replicate, five virgin females per plant) tethered with virgin female beetles in each replicate. We compared numbers of grubs in the following generation by retrieving these potted plants in the fall. Because of crop destruction requirements in blueberries for the sprayable pheromone, we were able to evaluate only the macrodispensers. All experimental protocols were similar in blueberries with the exception that each dispenser was loaded with only 300 mg of pheromone for a total of 7.5 g a.i./ha (10 times lower rate than nursery). Fig. 2. Evaluation of sprayable pheromone and macrodispensers in nursery (A), and macrodispensers in blueberries (B). There were three replicates in both crops. Pheromone trap captures in plots treated with sprayable pheromone and macrodispensers were 95 and 78% lower than in untreated nursery plots. The majority of the beetles in the macro dispenser treated plots were captured during the first few days after the deployment of the dispensers (Fig. 2A). This is probably because of initial slow release of pheromone from the dispensers. In blueberries where we used a 10X lower rate of pheromone, reduction in trap captures was equally impressive. Trap captures in the dispenser plots were 88% lower compared with untreated blueberry plots. Larval density in the following generation followed the same general trend as the trap shutdown in nursery (Fig. 3). Fewer grubs were present in both sprayable and macrodispenser treated nursery plots compared with untreated control plots. Fig. 3. Larval density (Mean ±SEM) in potted nursery plants tethered with virgin oriental beetle females in plots treated with sprayable pheromone, macrodispensers and untreated control plots. The preliminary data presented here provide for the first time evidence of the feasibility of mating disruption of a coleopteran pest. The development of mating disruption technology will further increase non-toxic pest management options in these cropping systems. This technology is also compatible with other pest management strategies and can be easily incorporated into current IPM programs. However, further work is required to resolve factors such as pheromone dose, dispenser deployment strategies, number of sprayable pheromone applications per season, and the relative efficacy of sprayable versus macrodispenser technology. Trécé Japanese beetle traps baited with rubber septa (300 µg loading of the major component) are widely used for monitoring and delineating populations of Oriental beetle in blueberries and nurseries. Nurserymen and blueberry growers often request extension personnel to interpret Oriental beetle trap catches to determine if an insecticide intervention is necessary. Because we do not have data on the relationship between trap catches and grub densities in the following generation, it has often become a guessing game interpreting trap captures. Determination of the relationship between male trap catch and larval density will enhance our ability to interpret trap catches and delineate populations that require insecticide interventions. DEVELOPMENT OF ENTOMOPATHOGENIC NEMATODES AND NEMATODE-INSECTICIDE SYNERGESTIC COMBINATIONS FOR ORIENTAL BEETLE MANAGEMENT Entomopathogenic nematodes offer an environmentally safe and highly IPM compatible alternative to chemical insecticides for the control of white grubs. When applied under the right conditions, these nematodes are as effective as chemical insecticides (Georgis and Gaugler 1991). Much of the work on using nematodes for white grub control in the United States, however, has concentrated on the Japanese beetle that appears to be among the most nematode-susceptible white grubs species (Koppenhöfer, unpublished data). Information on the nematode-susceptibility of the Oriental beetle is very limited, but generally this species appears to be less susceptible to the commonly used nematode species and strains such as Heterorhabditis bacteriophora and Steinernema glaseri (Koppenhöfer, Polavarapu, unpublished data). Because nematode efficacy appears to vary both with nematode and white grub species (Koppenhöfer, unpublished data; P. Grewal, Ohio State University, personal communication), it is important to screen additional nematode species/strains against the Oriental beetle. We have recently recovered new isolates of H. bacteriophora and a potentially new species of Steinernema from Oriental beetle larvae in NJ. Preliminary observations suggest that especially Steinernema spec. is highly pathogenic to Oriental beetle larvae (Table 1). Table 1. Percentage mortality (± SE) of Oriental beetle 3rd instar exposed to 400 nematodes in 30 ml plastic cups filled with soil. Treatments were replicated 4 times with 10 cups per replicate. Nematode species (strain)...7 DAT...14 DAT Steinernema spec. (OB)...100 ± 0 a...100 ± 0 a Steinernema glaseri (NC)...50 ± 9 b...68 ± 5 b Heterorhabditis bacteriophora (TF)...33 ± 8 b...48 ± 4 b Means followed by same letter within columns are not significantly different (Tukey, P < 0.05) Mortality in the control was 0%. While new nematode isolates may prove to be more effective for Oriental beetle control than the older isolates studied so far, many turf and ornamentals situations require extremely high control efficacy that nematodes may only provide at uneconomically high application rates. Combination of nematodes with synergistic agents may be an avenue to establish nematode use also in the most stringent situations at reduced cost and insecticide use. Several studies have shown that the efficacy of entomopathogenic nematodes to curatively control white grubs can be improved if they are integrated with other pathogens but these combinations have limitations. For example, the combination of nematodes and Paenibacillus (=Bacillus) popilliae Dutky (Thurston et al. 1994) is feasible only for long-term control in high economic threshold situations whereas the combination of nematodes and Bacillus thuringiensis Berliner Buibui strain (Koppenhöfer and Kaya 1997, Koppenhöfer et al. 1999) is feasible only for scarab species that are sufficiently susceptible to this bacterium. In addition, the Buibui strain is presently not commercially available. A more efficient combination with wider applicability should be that of nematodes and the chloronicotinyl insecticide, imidacloprid (Koppenhöfer and Kaya 1998, Koppenhöfer et al. 2000a). Currently, imidacloprid is one of the most popular insecticides for preventative white grub control because of its high efficacy, relatively low vertebrate toxicity, low application rates, and long systemic persistence (Schroeder and Flattum 1984, Elbert et al. 1991). Because its efficacy declines with advancing white grub development (Potter 1998), imidacloprid is applied in a preventative approach, the optimum period for application being during the month preceding egg hatch until the time when grubs are beginning to hatch (Potter 1998). However, white grub outbreaks are difficult to predict because they tend to be localized and sporadic and the eggs and first instars are difficult to sample for. As a result imidacloprid is applied over large areas although often only small fractions of lawns may require grub control making its use very expensive. While the direct effect of imidacloprid on beneficial invertebrates in turf was relatively small in experiments (Kunkel et al. 1999), in the long-term its high efficacy against many turfgrass pest combined with its large-area application is likely to dramatically reduce predators and especially more specific parasitoids and pathogens by depriving them of prey/hosts. The combination of imidacloprid and nematodes would allow curative treatments against older white grub stages, and because these stages are easier to detect, treatments could be limited to infested areas only, reducing cost and environmental impact. Koppenhöfer and Kaya (1998) and Koppenhöfer et al. (2000a) have shown that combined applications of the scarab-adapted entomopathogenic nematodes Steinernema glaseri or Heterorhabditis bacteriophora and imidacloprid resulted in synergistic mortality of 3rd-instars white grubs. This interaction was observed over a range of imidacloprid rates, with simultaneous or delayed nematode application, and for five scarab species with different degrees of nematode susceptibility. The degree of interaction, however, was usually greater for S. glaseri than for H. bacteriophora. Koppenhöfer et al. (2000b) showed that the major factor responsible for this synergistic interaction is the general disruption of normal nerve function due to imidacloprid resulting in reduced activity of the grubs. This sluggishness facilitates host attachment of infective juvenile nematodes and subsequent infection. The above studies only included the Oriental beetle in one greenhouse experiment, but recent experiment confirmed the synergism for Oriental beetle under laboratory and field conditions (Koppenhöfer unpubl. data; Table 2). Table 2. Effect of treatment with imidacloprid (330 g a.i./ha), H. bacteriophora (2.5x109/ha), and their combination on a mixed natural population of Oriental and Japanese beetle larvae (90% 3rd instar at application). Shown are mean numbers of larvae/0.1 m2 (% reduction) at 22 DAT (n=9). Treatment...Oriental beetle...Japanese beetle Control...2.2 ± 0.8 a...3.9 ± 0.9 a Imidacloprid...0.9 ± 0.4 b (59)...1.4 ± 0.6 b (64) H. bacteriophora...1.1 ± 0.5 ab (50)...1.1 ± 0.5 b (72) Imidacloprid + H. bacteriophora...0.0 ± 0.0 c (100)*... 0.0 ± 0.0 c (100) Means followed by same letter within columns are not significantly different (Tukey, P < 0.05) *Significant synergistic interaction in the combination treatment (Chi-square test, P < 0.05 ). While imidacloprid is still the only neonicotinoid insecticide registered for use in turfgrass, nurseries, or blueberries, several other compounds are in development (thiacloprid; a chloronicotinyl compound like imidacloprid) or are about to be registered (thiamethoxam; a thianicotinyl compound). Thiamethoxam has already been field-tested and has shown the same activity against white grubs including the Oriental beetle as imidacloprid, i.e., it is highly effective when applied preventatively but is not effective against 3rd instars (D. Cox, Novartis, personal communication). Thiacloprid has not been field tested yet, but has shown a similar activity spectrum in laboratory studies as imidacloprid (C. Silcox, Bayer Corp., personal communication). We propose to expand our studies on synergistic interaction to these new compounds and new nematode isolates with high pathogenicity for Oriental beetle larvae. Our observations on the efficacy of new nematode isolates as well as the synergistic interaction of nematodes with new neonicotinoid insecticides for Oriental beetle management will also have implications for the management of other white grub species especially Japanese beetle in the turfgrass, ornamentals, blueberries, and other crops beyond New Jersey and the Northeast. Objectives: The overall objective of this proposal is to develop novel methods to manage Oriental beetle populations that are environmentally sound and compatible with an IPM approach. More specifically, the following are the objectives of this proposal: 1) Develop mating disruption technology using sprayable, microencapsulated formulation and high-release widely spaced dispenser systems. 2) Establish relationships between pheromone trap captures and larval density in the following generation. 3) Evaluate new species/strains of entomopathogenic nematodes and evaluate the potential synergy between nematodes and some novel insecticides. USDA CRIS data |
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