Masked Chafer Research Articles

Kairomones from scarabaeid grubs and their frass as cues in below‐ground host location by the parasitoids Tiphia vernalis and Tiphia pygidialis

AbstractCues used in below‐ground host‐searching behaviour and host discrimination were examined for Tiphia vernalis Rohwer and Tiphia pygidialis Allen (Hymenoptera: Tiphiidae), ecto‐parasitoids of root‐feeding larvae of the Japanese beetle, Popillia japonica Newman, and masked chafers, Cyclocephala spp. (Coleoptera: Scarabaeidae), respectively. Response to potential stimuli was compared in dual choice tests in an observation chamber filled with soil. Each wasp showed species‐specific, directed movement along residual body odor trails made by dragging its respective host through the soil. Presence of a grub was not necessary for wasps to follow such trails. Frass from either host‐ or non‐host grubs elicited trail‐following, but each Tiphia species followed frass trails from its respective host when a choice was presented. Frass trails elicited stronger responses than body odor trails. The combination of host frass and body odor elicited the strongest trail‐following responses. Our results suggest that once in the soil, Tiphia spp. locate their hosts using contact kairomones present in grub body odor trails and frass.

Toxicity of Indian Mustard and Allyl Isothiocyanate to Masked Chafer Beetle Larvae

Alternatives for control of soil-inhabiting pests are needed due to the phase-out of methyl bromide. One possible alternative is using the pesticidal properties of compounds released by macerated Brassica tissues. In this study, larvae of masked chafer beetles (Cyclocephala spp.) were placed in soil amended with Brassica juncea L. (PI 458934) tissue. Allyl isothiocyanate (AITC) levels were positively correlated to larval mortality, with the 8% B. juncea treatment resulting in 100% larval mortality with an average AITC concentration of 11.4 mg per liter of soil atmosphere. Although B. juncea produces high levels of AITC, the mass of tissue required for significant insecticidal activity against Cyclocephala spp. also is high, between 4 and 8% of soil mass for this plant accession. Accepted for publication 23 May 2002. Published 10 June 2002.

Identification and Impact of Egg Predators ofCyclocephala luridaandPopillia japonica(Coleoptera: Scarabaeidae) in Turfgrass

Field experiments were conducted to identify predators of southern masked chafer, Cyclocephala lurida Bland, and Japanese beetle, Popillia japonica Newman, eggs in turfgrass soil and to measure the predation that occurs. Identification of egg predators was determined by direct observation through buried Plexiglas plates of artificially placed eggs. Predation rates of Japanese beetle eggs was further measured using buried bait stations filled with eggs. Up to 73% of eggs in the soil were taken within a 72-h period. Ants were found to be the predominant predator accounting for up to 83% of the eggs taken. One species of ant, Solenopsis molesta (Say), proved to be the primary ant predator of eggs in turfgrass.

Synergism of Entomopathogenic Nematodes and Imidacloprid against White Grubs: Greenhouse and Field Evaluation

Abstract In previous greenhouse studies, the insecticide imidacloprid and the entomopathogenic nematode Heterorhabditis bacteriophora Poinar interacted synergistically against third instars of the masked chafers Cyclocephala hirta LeConte and C. pasadenae Casey (Coleoptera: Scarabaeidae). We tested this interaction for two additional nematode species and three additional scarab species under field conditions. In greenhouse tests, H. bacteriophora and Steinernema glaseri (Steiner) interacted synergistically against third instars of the Japanese beetle, Popillia japonica Newman, the oriental beetle, Exomala orientalis Waterhouse, and the masked chafers Cyclocephala borealis Arrow, C. pasadenae, and C. hirta. The degree of interaction varied with nematode species. The strongest synergism occurred between imidacloprid and S. glaseri. Synergism between imidacloprid and H. bacteriophora was weaker and the interaction was not always significant. Combinations of imidacloprid and S. kushidai Mamiya only resulted in additive mortality. The synergistic interaction was also observed in field trials but the results were more variable than those under greenhouse conditions. The combination of nematodes and imidacloprid could be used for curative treatments of white grub infestations, especially against scarab species that are less susceptible to nematodes and/or imidacloprid. This combination has a low environmental impact and high compatibility with natural biological control of turfgrass insects. The possible roles of these combinations in augmentative control approaches are discussed.

Influence of Application Timing of Insecticides on Control of Southern Masked Chafer, 1997

Abstract This study was conducted in Lincoln, NE, on a golf course rough. The turf (50% Kentucky bluegrass and 50% perennial rye) was maintained at a mowing height of 2.0 inches. Thatch accumulation (finger compressed) in the plot area was 0.75 inch. Field conditions at the study site were; soil type, silty clay loam; soil organic matter, 3.5%; soil pH, 6.5; water pH, 7.0. Environmental conditions at the time of application, (17 Jun, and 12 Aug) were as follows: soil moisture 20%, and 22% by wt respectively; air temperature 84° F, and 64° F; soil temperature 65° F, and 66° F; relative humidity 32%, and 88%; wind direction and velocity 245° at 3 mph., and 345° at 7 mph. Plots were 6 X 10 ft and the experimental design was a RCB with 4 replications. Liquid insecticides were applied using a CO2 sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 87 gpa. Following applications, plots were irrigated with 0.25 inches of water. Post-treatment precipitation totaled 8.34 inches. Treatments were evaluated 80 days after the first application on 05 Sep by removing from each plot six, 8-inch diam turf-soil cores (2.10 ft2 total area) to a depth of 3 inches and counting the number of surviving grubs.

Influence of Post-Application Irrigation on Control of Annual White Grubs on a Golf Course Fair-Way, 1996

Abstract This study was conducted in Lincoln, NE on a golf course fairway. The turf (20% Kentucky bluegrass and 80% perennial rye) was maintained at a mowing height of 11/16 inch. Thatch accumulation (finger compressed) in the plot area was 0.375 to 0.50 inch. Field conditions at the study site were: soil type, silty clay loam; soil organic matter, 4%; soil pH, 6.2; water pH, 7.0. Environmental conditions at the time of application were as follows: soil moisture 12% by wt.; air temperature 72°F; soil temperature 72°F; relative humidity 43%; wind direction and velocity 6° at 7 mph. Plots were 6 X 10 ft and the experimental design was a RCB with 3 replications. Insecticides were applied once on 9 Jul and twice on 11 Jul. Liquids were applied using a CO2 sprayer with a TeeJet® 8002 nozzle at 30 psi and delivering 2 gal/1000 square feet. A pre-calibrated Gandy 24H12 drop spreader was used to apply granular insecticides. Post-application irrigations were applied as follows: 09 Jul application, none; 11 Jul, first application, 0.35 inch; 11 Jul, second application with syringe, approximately 0.125 inch. Normal irrigation was resumed after 48 h. Precipitation between application and evaluation totaled 11.3 inches. Treatments were evaluated 57 DAT on 4 SEP by removing from each plot three, 8-inch diam turf-soil cores (1.05 ft2 total area) to a depth of 3 inches and counting the number of surviving grubs. Insecticides were applied prior to the onset of masked chafer oviposition.

Coexistence of two steinernematid nematode species (Rhabditida: Steinernematidae) in the presence of two host species

Interactions between entomopathogenic nematode species with different foraging strategies were examined in the presence of two host species in soil. Based on differences in insect behavior and nematode pathogenicity, we hypothesized that black cutworm, Agrotis ipsilon (Hufnagel), larvae would be more likely to serve as hosts for Steinernema carpocapsae or Steinernema riobravis, whereas masked chafer grubs, Cyclocephala hirta LeConte, would be more likely to serve as hosts for Steinernema glaseri. In the laboratory, the highest mortality of and nematode penetration in A. ipsilon were observed for S. carpocapsae followed by S. riobravis and S. glaseri. In C. hirta, substantial mortality and nematode penetration were only observed for S. glaseri. After combined applications of two nematode species, S. carpocapsae dominated over S. glaseri in A. ipsilon, whereas S. glaseri and S. riobravis shared the host resources. In C. hirta, S. glaseri outcompeted each of the other species. In the greenhouse, containers with turfgrass were inoculated with S. glaseri, S. carpocapsae, or S. riobravis, or combinations of S. glaseri with either S. carpocapsae or S. riobravis. Four days later, each container received seven A. ipsilon and nine C. hirta larvae, and new insects were added at 30-day intervals. The densities of infective juvenile nematodes were monitored over 150 days by taking soil samples from each container. In the single species treatments, numbers of S. carpocapsae and S. riobravis increased after 30 days, decreased thereafter and remained low. Steinernema glaseri numbers fluctuated between low and high densities. In the combination of S. glaseri and S. carpocapsae, both species were depressed compared with the single species treatment. In the combination of S. glaseri and S. riobravis, both species coexisted and showed parallel fluctuations but S. glaseri dominated numerically. Our observations indicate that two entomopathogenic nematode species may successfully coexist in an area by having different foraging strategies that separate nematode species spatially, exhibiting host specificity, and occupying a different niche. In the field, patchy distribution and alternate hosts may also support nematode coexistence.

Cultural Practices Affect Root-Feeding White Grubs (Coleoptera: Scarabaeidae) in Turfgrass

Cultural practices were manipulated before or during seasonal flights of Japanese beetle, Popillia japonica Newman, and masked chafers, Cyclocephala spp., to study effects on grub densities in tall fescue or Kentucky bluegrass turf. Masked chafer grubs were consistently smaller and less abundant in turf that had been treated with aluminum sulfate to reduce soil pH and in high-mown turf. High mowing or application of aluminum sulfate before beetle flights reduced total biomass of white grubs in tall fescue by as much as 55 and 77%, respectively. However, where spatial gradients in soil moisture occur, the positive response of grub populations to moisture may override effects of those treatments. Grub densities were not affected by spring applications of lime or urea or by aerification of plots before beetle flights. Plots that were irrigated during beetle flights incurred significantly higher densities of both P. japonica and Cyclocephala spp. grubs than did nonirrigated turf. The use of a 2,247- kg roller to compact the soil before beetle flights did not affect subsequent grub populations, and the roller was not effective for remedial control of 3rd instars in the fall. Application of organic fertilizers (composted cow manure or activated sewage sludge) resulted in significant increases in grubs of green June beetle, Cotinis nitida L., in 1 of 2 yr. Cultural practices may have general or species-specific effects on densities of white grubs. This study suggests that witllolding irrigation during peak flight of beetles, raising cutting height, and light application of aluminum sulfate in spring may help to reduce the severity of subsequent grub infestations.

Efficacy of Chemical and Biological Insecticides for Control of Overwintered Japanese Beetle and Northern Masked Chafer Larvae on a Golf Course Rough in Summit County, Ohio, 1995

Abstract The study was located on a golf course rough at Valley View Golf Course in Akron, Ohio. Insecticides were applied 3 May to plots 5 X 10 ft (1.5 X 3.1 m) arranged in a RCB, replicated 3 times. Liquid treatments were applied with a CO2 sprayer and TeeJet™ XR8010VS nozzles at 30 psi (2.19 kg/cm2) pressure that delivered a volume of 3.1 gal/1000 ft2 (1262 liter/ha). The granular treatment was applied with a drop spreader. After all treatments were applied, the area was irrigated with approximately ½inch (13 mm) of water using the golf course system. Environmental conditions at the time of treatment were as follows: White grubs: approximately 15/ft2, 60% NMC 3rd instars, 40% JB 3rd instars; Turf: level, dry, 1.0-2.0 inch (2.5-5.0 cm) ht, 50% bentgrass, 30% annual bluegrass, and 20% Kentucky Bluegrass, no thatch; Soil: moist, 50°F at 1 inch (2.5 cm) and 3 inch (7.6 cm); Weather: sunny, 47°F, no wind. Efficacy data taken 30 May (28 DAT) were based on the number of live larvae in four samples 7X7 inch (17.8 X 17.8 cm) from each plot. Analysis of variance was done on plot totals transformed to log (X+l) and means separated by LSD test at P = 0.05.

Feeding by Japanese Beetle and Southern Masked Chafer Grubs on Lawn Weeds

Root‐feeding white grubs (Coleoptera: Scarabaeidae) are among the most injurious insect pests of cool‐season turfgrasses; however, little is known about the influence of common lawn weeds on white grub populations. Greenhouse studies were conducted to evaluate the suitability of six weed species and one turfgrass including white clover (Trifolium repens L.), red clover (T. pratense L.), large crabgrass [Digitaria sanguinalis (L.) Scop.], annual bluegrass (Poa annua L.), buckhorn plantain (Plantago lanceolata L.), dandelion (Taraxacum officinale Weber), and Kentucky bluegrass (Poa pratensis L.) as food for grubs of the Japanese beetle (Popillia japonica Newman) and southern masked chafer (Cyclocephala lurida Bland). Third instars of both species fed upon and reduced root biomass of all weeds tested, and in some cases, reduced foliage yields as well. Survival of both grub species was as high, or higher, on most weeds as on Kentucky bluegrass. Dandelion and white clover appear to be particularly poor hosts for P. japonica and C. lurida, respectively.

Chemically Mediated Sexual Attraction of Male Cyclocephala lurida (Coleoptera: Scarabaeidae) and Other Scarabaeid Beetles to Immature Stages

Adult females of the southern masked chafer, Cyclocephala lurida Bland, produce a volatile sex pheromone that attracts conspecific males. Previously we documented that extracts of 3rd-instar Cyclocephala spp. grubs contain one or more compounds that attract males and stimulate copulatory attempts when these males arrive at the source of the odor. Attraction of males to larvae appears to be undocumented for any other insect species. We examined developmental expression of the production of this attractant within Cyclocephala spp., and evaluated hexane extracts of other species of scarabaeid grubs for attractiveness to C. lurida or conspecifics. We found that the attractant is not limited to the postoverwintering last instar, but rather is present in all larval stages and in male and female pupae. Extracts of Cyclocephala spp. grubs also attracted males of the northern masked chafer, Cyclocephala borealis Arrow. Hexane extracts of 3rd instars of Japanese beetles, Popillia japonica Newman, and green June beetles, Cotinis nitida L., were not attractive to male C. lurida , indicating that there is some phylogenetic specificity to this unusual production of a sex-specific attractant. Third instars of C. nitida do not attract conspecific males. Studies of male attraction to conspecific immature stages in Cyclocephala spp. and other Scarabaeidae may provide insights into the evolutionary origins of chemical communication systems.

Tolerance of Cool-Season Turf grasses to Feeding by Japanese Beetle and Southern Masked Chafer (Coleoptera: Scarabaeidae) Grubs

Response of Kentucky bluegrass, Poa pratensis L.; tall fescue,Festuca arundinacea Schreber; hard fescue, F ovina L. var. duriuscula; perennial rye grass, Lolium perenne L.; and creeping bent grass, Agrostis palustris (Hudson), to herbivory by root-feeding by grubs of Japanese beetle, Popillia japonica Newman, and southern masked chafer, Cyclocephala lunda Bland, was evaluated in greenhouse trials. Potted turf grasses were infested with initial densities equivalent to 73 or 146 grubs per 0.1 m2 in spring and fall trials, and effects on plant growth and grub survival were determined. All turf grasses tolerated significant damage to roots without loss of foliage yield. In fact, feeding by grubs stimulated increased growth of foliage in some grasses. With comparable densities of grubs, loss of roots tended to be proportionately less in creeping bent grass than in other grass species. Survival of grubs was similar in all turf grasses, and between low and high grub densities. P. japonica caused greater loss of roots than C. lurida in the spring trial, but the reverse was true in the fall. Root loss per grub decreased with increasing larval density, suggesting food limitation even though root systems were not completely devoured. Implications of these findings for tolerance and recovery of grub-damaged turf grasses are discussed.

Integration of Entomopathogenic Nematodes with Bacillus thuringiensis or Pesticidal Soap for Control of Insect Pests

The integration of entomopathogenic nematodes and Bacillus thuringiensis subspecies kurstaki or a pesticidal soap controlled insect pests inhabiting the soil and foliage in the greenhouse. The nematode Heterorhabditis bacteriophora controlled larvae of the masked chafer Cyclocephala hirta or the black vine weevil Otiorhynchus sulcatus in the soil and a commercial formulation of B. thuringiensis (Javelin) controlled larvae of the cabbage looper Trichoplusia ni on foliage. The combination of H. bacteriophora or Steinernema carpocapsae with a pesticidal soap (M-Pede) was effective against larvae of the spotted cucumber beetle Diabrotica undecimpunctata undecimpunctata in soil and all feeding stages of the cabbage aphid Breuicoryne brassicae on foliage. After combining and immediately applying both the nematode and B. thuringiensis or pesticidal soap, positive results were obtained against insects in the soil and on foliage. The combinations of nematode and B. thuringiensis or pesticidal soap were held for 4 days with or without aeration, and the fate of the nematodes was observed daily. Both nematode species survived well in the B. thuringiensis formulations with aeration. Without aeration, S. carpocapsae was unaffected by the B. thuringiensis formulations, but H. bacteriophora showed poor survival in the two commercial formulations (Javelin after 1 day and Biobit after 3 days). With or without aeration, both nematode species were adversely affected in the pesticidal soap, but H. bacteriophora showed a higher mortality rate than S. carpocapsae.

Damage Relationships of Japanese Beetle and Southern Masked Chafer (Coleoptera: Scarabaeidae) Grubs in Cool-Season Turfgrasses

Relative tolerance to root herbivory by 3rd-instar Japanese beetle, Popillia japcnica Newman, and southern masked chafer, Cyclocephala lurida Bland, grubs was evaluated in turfgrass plots of Kentucky bluegrass, Poa pratensis L., perennial ryegrass, Lolium perenne L., creeping bentgrass, Agrostis palrtstris (Hudson), hard fescue, Festuca ovina L. var. durillscula, and both Acremonium endophyte-infected and endophyte-free tall fescue, Festuca arundinacea Schreber. Field enclosures and rooting boxes were infested with densities of grubs ranging from 0 to 60 per 0.1 m2, and effects on aesthetic quality, canopy temperature, foliage yield, and root strength were measured. Damage thresholds were variable but appeared to be milch higher in all grasses than the rule-of-thumb estimates commonly used in the turf industry. Initial densities of at least 15-20 grubs per 0.1 m2 were reqllired to cause any reduction in aesthetic quality of most turfgrasses, and in some cases, initial densities of 60 grubs per 0.1 m2 caused no apparent damage. Canopy temperatures were not consistently correlated with density of grubs. Damage by C. lurida was greater in endophyte-free than in endophyteinfested tall fescue in some trials and was greater than, or equal to, that of P. japonica in all grasses. Variability in the turfgrass system complicates prediction of turf grass damage based solely on grub density.

Irrigation and Nitrogen Fertilization Effects on White Grub Injury to Kentucky Bluegrass and Tall Fescue Turf

Root‐feeding white grubs (Coleoptera: Scarabaeidae) are important pests of cool‐season turfgrasses in the eastern USA. We studied effects of irrigation and N fertilization on Kentucky bluegrass (Poa pratensis L.), and tall fescue (Festuca arundinacea Schreb.) response to grub damage under greenhouse and field conditions. Potted turfgrasses, with or without Japanese beetle (Popillia japonica Newman) grubs (122/0.1 m2), were maintained under two irrigation regimes, with or without supplemental N fertilizer (204 kg N ha−1). Foliar and root yields, and grub survival were measured after 4 wk. In the field, sod was grown in rooting boxes, with or without spring fertilization (146 kg N ha−1) and fall irrigation (2.54 cm wk−1). Half of the plots were infested with southern masked chafer (Cyclocephala lurida Bland) grubs (66 /0.1 m−1) in late August and effects on aesthetic damage, surface temperature, foliar yield, root strength, and grub survival were measured for 9 wk. Grubs severely damaged roots of both grasses regardless of management regime. Within regimes, however, this damage significantly reduced follar yield only in turf that received both N and high irrigation. In the greenhouse, grub‐damaged grasses that received remedial N, nevertheless, had higher foliar yield than did non‐fertilized grasses without grubs. In rooting boxes, fall irrigation following spring fertilization enhanced visual quality of grub‐infested turf and root strength of grub‐damaged Kentucky bluegrass. Survival of grubs did not differ between grass species or fertilization regimes, but more P. japonica survived in pots receiving high irrigation. Irrigation during the fall feeding period, followed by remedial N fertilization, may promote tolerance and recovery of grub‐damaged turfgrasses.

Bacillus and Serratia species for Scarab control

Few microorganisms are commercially available for use against white grubs (larvae of Scarabaeidae). Entomopathogenic bacteria, particularly Bacillus popilliae, have been used the longest for white grub suppression. Other bacteria, namely B. thuringiensis and Serratia spp. offer promise for future control. This papes examines two genera of bacteria (Bacillus and Serratia) from the historical and current perspective. Bacillus popilliae, the firs microbial control agent registered in the United States, has a long history of use in suppressing populations of the Japanese beetle, Popillia japonica. However, lack of in vitro production and the slow and sporadic nature of its activity, severely limits its utilization. B. thuringiensis, the most widely used microbial pesticide, has not been used for scarab, control. However, strains with scarab activity have recently been discovered. Scarab larvae have been collected in the United States with signs and symptoms similar to those characteristic of amber disease (caused by Serratia entomophila) in the New Zealand grass grub, Costelytra zealandica. A total of 147 bacteria have been obtained from the digestive tracts of larvae of the Japanese beetle and masked chafers, Cyclocephala spp., as well as from larvae and soil collected in Japan and China. Seventy five of these have been identified as Serratia spp. Most (40) of the remaining bacteria are in the genus Enterobacter. A majority of the bacteria (73) and of the Serratia (38) came from P. japonica.

Control of White Grubs at the Purdue University Agronomy Research Center, W. Lafayette, In, 1994

Abstract Treatment plots were 2 × 2 ft, arranged in a RCB design, replicated 5 times. A PVC cylinder (6 inch inside diameter) was buried 4 inches into the soil and projected 1 inch above the soil in the center of each plot. Five third-instar grubs (mixed population consisting of about 90% Japanese beetles and 10% Southern masked chafers) were infested within each cylinder 5 d prior to treatment, 2 Sep. Granular formulations were applied with a homemade salt shaker. All plots received 0.5 inches of irrigation immediately after treatment. Conditions at the time of treatment were: air temp., 21°C; soil temp, at 1 inch, 20°C; thatch depth (natural), 0.13-0.25 inches; soil texture, silt loam; wind speed 3-5 mph. Efficacy was evaluated 30 DAT by extracting the cylinders, separating the soil and grass, and recording the number of live grubs.

Surface Application and Subsurface Placement of Synthetic Insecticides and a Bacillus Thureng1Ensis Formulation for Control of Northern Masked Chafer and Japanese Beetle Larvae on A Golf Course Fairway, 1994

Abstract The study was located on a golf course fairway and rough at Akron, OH. Insecticides were applied 17 Aug to plots 8 × 10 ft (2.4 × 3.1 m) arranged in a RCB, replicated 4 times. Liquid treatments were surface applied with a CO2 sprayer with Teejet XR8010VS nozzles at 30 psi (2.11 kg/cm2) pressure that delivered a volume of 3.1 gal/1000 ft2 (1262 liter/ha). BT treatments received VA inch (6 mm) irrigation immediately after each plot was treated. Subsurface treatments were placed using a Cushman Ryan prototype applicator which cut 11 slits into the turf on 2 inch (5.1 cm) centers and deposited granules Vi to 3A inch (ca 2 cm) deep. Surface granular materials were applied using a drop spreader. The entire experimental area was irrigated approximately lA inch (6 mm) of water after all treatments were applied using the golf course system. Environmental conditions at the time of treatment were as follows. Population: ca 20/ft2; 50% NMC, 20% 1st and 80% 2nd instars; 50% JB, eggs present, 40% 1st and 60% 2nd instars, 60 larvae/ft2. Turf: level, dry, 1.25 to 2 inches (3 to 5 cm) height, 40% bentgrass, 30% Kentucky bluegrass, and 30% annual bluegrass. Thatch: none. Soil: moist, 82°F at 1 inch (2.5 cm) and 77°F at 3 inches (7.6 cm). Weather: cloudy, 81°F, 0 mph. Efficacy data taken 27 Sep (41 DAT) were based on the number of live larvae in four 7 × 7 inch (17.8 × 17.8 cm) from each plot. Analysis was done on plot totals and means separated by LSD test.

Preferences of Japanese Beetle and Southern Masked Chafer (Coleoptera: Scarabaeidae) Grubs Among Cool-Season Turfgrasses

Feeding preferences of Japanese beetle, Popillia japonica Newman, and southern masked chafer, Cyclocephala lurida Bland, grubs for six common cool-season turfgrasses were evaluated in choice tests in the greenhouse. On the basis of larval distributions, Popillia japonica consistently preferred perennial ryegrass, Lolium perenne L., over all other turfgrasses tested. In contrast, C. lurida showed no consistent pattern of preference. Presence of one grub species did not affect distribution of the other species. Grubs did not discriminate between tall fescue, Festuca arundinacea Schreb., infected with the endophyte Acremonium coenophialum Morgan-Jones & Gams and endophyte-free tall fescue.

Effect of Irrigation and Spray Volume on Efficacy of Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae) Against White Grubs (Coleoptera: Scarabaeidae)

Infective juveniles of the entomopathogenic nematode Heterorhabditis bacteriophora Poinar (Cl strain) were applied to Kentucky bluegrass (Poa pratensis L.) to determine the effect of irrigation on efficacy against larvae of the Japanese beetle, Popillia japonica Newman, and the northern masked chafer, Cyclocephala borealis Arrow. Excellent control (>;80%) was achieved with 1.25-5.0 billion nematodes per hectare when plots received irrigation before treatment application and again within 24 h after treatment application. When plots were not irrigated before treatment, results were inconsistent (range, 0-92% of the control). Two spray volumes (0.16 liters/m2 and 0.32 liters/m2) had no significant effect on nematode efficacy.