Management of early-instar Japanese beetle (Coleoptera: Searabaeidae) in field-grown nursery crops.

Numerous field studies were conducted in commercial nurseries in Tennessee from 1996 through 1999 to evaluate chemical and biological treatments, application timing and rates, and method of application for control of early instars of Japanese beetle, Popillia japonica Newman. Insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, fipronil, halofenozide, imidacloprid, permethrin, tefluthrin, thiamethoxam, and trichlorfon. Biological treatments included entomopathogenic nematodes (Heterorhabditis bacteriophora HP88 or H. marelatus, Bacillus thuringiensis Berliner subspecies japonensis Buibui strain, and Beauveria bassiana (Balsamo) Vuillemin. All treatments were applied on the soil surface or injected into the soil around the base of each tree. Tree type and size varied among and within tests, however, the sampling unit (61-cm-diameter root ball) remained the same throughout all tests. The biological treatments provided poor-to-moderate control (0-75%) of Japanese beetle larvae. Imidacloprid was the most frequently evaluated insecticide and achieved 91-100, 87-100, 83-100, and 41-100% control with applications in May, June, July, and August, respectively. Halofenozide treatments were not significantly different from imidacloprid treatments with one exception. Halofenozide provided 60-87, 85-100, and 82-92 control with applications made in June, July, and August, respectively. Fipronil and thiamethoxam were evaluated to a lesser extent but both performed similarly to imidacloprid. Most other insecticide treatments were less successful in reducing numbers of Japanese beetle larvae and with few exceptions achieved <50% control.     

Effect of neonicotinoid synergists on entomopathogenic nematode fitness

In previous greenhouse and field studies, the neonicotinoid insecticide imidacloprid interacted synergistically with five entomopathogenic nematode species against five scarab species. Two other neonicotinoids, thiamethoxam and acetamiprid, showed a weaker interaction with nematodes in scarab larvae. Entomopathogenic nematodes have the potential to recycle in hosts after inundative applications, thereby increasing the persistence of nematodes and insect control. Thus we investigated the effect of neonicotinoids on nematode fitness after tank mixing and after combined applications. Tank mixing only had a negative effect on nematode survival and infectivity in a few nematode–insecticide combinations and only if both insecticide concentration and exposure time were several times higher than typical for field applications. Combined application of nematodes with imidacloprid generally had no negative effect on the percentage of scarab cadavers producing progeny or the number of nematode progeny emerging per cadaver. In experiments with a synergistic increase in scarab mortality, the total number of progeny in combination treatments was up to four times higher than in nematodes only treatments. Similarly, nematode populations in soil from combination treatments were 13.2 times greater than for nematodes only treatments at 28 days after treatment. Combined imidacloprid–nematode applications did not affect the pathogenicity or infectivity of the nematode progeny. Combining thiamethoxam with nematodes had no negative effects on nematode reproduction in the majority of treatments. However, due to the weaker interaction of thiamethoxam and nematodes on scarab mortality, the total number of nematode progeny per treatment generally did not increase compared with nematodes only treatments. The demonstrated tank mix compatibility of imidacloprid and nematodes improves the feasibility of combining these agents for curative white grub control. The positive effect of imidacloprid on nematode reproduction after combined application may increase the likelihood of infection of white grubs by subsequent generations of nematodes, thereby improving their field persistence and biological control potential.     

Effect of insecticides on Tiphia vernalis (Hymenoptera: Tiphiidae) oviposition and survival of progeny to cocoon stage when parasitizing Popillia japonica (Coleoptera: Scarabaeidae) larvae

The effect of insecticides on oviposition of Tiphia vernalis Rohwer and subsequent survival of parasitoid progeny to the cocoon stage was determined in the laboratory by using larval Japanese beetle, Popillia japonica Newman, as the host. Insecticides tested were imidacloprid, thiamethoxam, halofenozide, chlorpyrifos, and carbaryl at labeled rates. Female T. vernalis were allowed 2 d to parasitize P. japonica larvae after the parasitoids had received a 4-d exposure to insecticide-treated soil. Another group of female T. vernalis were allowed 2 d to parasitize P. japonica larvae that had been exposed to insecticide-treated soil for 3-4 d. Percentage of parasitism of P. japonica larvae in these trials after exposure of adult parasitoids to carbaryl, chlorpyrifos, halofenozide, or imidacloprid-treated soil (23.3-50.0%) or adult parasitoids to chlorpyrifos, halofenozide, or imidacloprid-treated grubs (33.0-56.7%) was not negatively affected relative to the control treatment (21.7-54.2%). A third group of adult T. vernalis and P. japonica larvae were simultaneously exposed to chlorpyrifos or carbaryl treatments. Percentage parasitism in these trials was lower for T. vernalis adults exposed to the chlorpyrifos and carbaryl (15.0-25.0%) relative to the control (57.5-62.5%) with the exception of one trial with carbaryl (40.0%). However, exposure of the parasitoid and P. japonica to chlorpyrifos 0.5X, carbaryl 0.5X, imidacloprid, halofenozide, or thiamethoxam in several trials resulted in parasitism that was equivalent or greater than (45.0-80.0%) the untreated control (57.5-62.5%). Japanese beetle larval mortality in these trials was greater in the insecticide and parasitoid combination (97.5-100.0%) than with insecticides alone (45.0-100.0%). Percentage of survival of T. vernalis progeny to the cocoon stage was not negatively affected by a 4-d adult parasitoid exposure to carbaryl and chlorpyrifos treated soil (11.7-16.7% versus 18.3% control) or a 2-d exposure to P. japonica-treated larvae (16.7-18.3% versus 28.3% control). However, simultaneous exposure of T. vernalis progeny and P. japonica larvae to chlorpyrifos- and carbaryl-treated soil resulted in no parasitoids surviving to the cocoon stage. Between neonicotinoids, thiamethoxam had more adverse impact on percentage parasitism (52.5%) and survival to the cocoon stage (10.0%) than imidacloprid (80.0 and 32.5%, respectively). Results of this study indicate soil incorporation of imidacloprid and halofenozide had minimal effect on the number of P. japonica larvae parasitized by T. vernalis or survival of T. vernalis progeny to the cocoon stage; therefore, they are more suitable for use with T. vernalis. In contrast, chlorpyrifos, carbaryl, and thiamethoxam lowered the number of T. vernalis progeny surviving to the cocoon stage, and carbaryl and chlorpyrifos reduced the number of P. japonica larvae parasitized. The soil incorporation of insecticides is discussed as one explanation for the minimal effects of some insecticides on T. vernalis.     

Control of Codling Moth,Cydia pomonella (Lepidoptera: Tortricidae), with Steinernema carpocapsae: Effects of Supplemental Wetting and Pupation Site on Infection Rate

Infection of cocooned codling moth (cydia pomonella) larvae by the entomopathogenic nematode Steinernema carpocapsae was studied in three field experiments. Factors that varied within or between experiments included method of application, type of substrate containing cocooned larvae, time when nematodes were applied, seasonal effects, and supplemental wetting before or after nematode application. Conventional air-blast sprayer applications of 0.5–5.0 million infective juveniles (IJs)/tree in fall resulted in ca. 30% mortality of larvae in cardboard trap bands, whereas hand-gun application (2 million IJs/tree) produced mortality of ca. 70%. Application in the evening caused higher larval mortality than application in the morning when no supplemental wetting was used after treatments. Morning and evening applications caused equivalent larval mortality when a postwetting treatment was included. In a trial conducted in midsummer, supplemental wetting, either before or after hand-gun application of 1 million IJs/tree, enhanced nematode-produced mortality. Mortality approached 100% if both pre- and postwetting was used. Larvae in exposed cocoons on apple wood were infected at a higher rate (86%) than those on wood in less exposed positions (73%) or in nonperforated cardboard (72%). Mortality rates for larvae in perforated cardboard were intermediate (77%). Application volumes used to deliver nematodes slightly enhanced infection rate of larvae in some substrates but not others. In one trial, parasitism of codling moth by the wasp Mastrus ridibundus (Ichneumonidae) was negatively correlated with nematode infection of codling moth larvae. Dissections showed that ca. 10% of larvae infected by nematodes had been attacked by the wasp.     

Infectivity of Four Species of Nematodes (Rhabditoidea: Steinernematidae, Heterorhabditidae) to the Asian Longhorn Beetle, Anoplophora glabripennis (Motchulsky) (Coleoptera: Cerambycidae)

Four species of entomopathogenic nematodes, Steinernema carpocapsae , Heterorhabditis bacteriophora , H. indica and H. marelatus , were tested for their ability to kill and reproduce in larvae of the Asian longhorn beetle, Anoplophora glabripennis (Motchulsky). The larvae were permissive to all four species but mortality was higher and production of infective juveniles was greater for S. carpocapsae and H. marelatus . The lethal dosage of H. marelatus was determined to be 19 infective juveniles for second and third instar larvae and 347 infective juveniles for fourth and fifth instar larvae. H. marelatus infective juveniles, applied via sponges to oviposition sites on cut logs, located and killed host larvae within 30 cm galleries and reproduced successfully in several of the larvae.     

Impact of four insecticides on Japanese beetle (Coleoptera: Scarabaeidae) egg predators and white grubs in turfgrass

Field experiments were conducted to measure the effects of four commonly used turfgrass insecticides (isofenphos, diazinon, imidacloprid, halofenozide) on white grubs (Coleoptera: Scarabaeidae) and ant predators of white grub eggs. Ant populations were measured over time with canned tuna, whereas predation by the ants was measured with artificially placed Japanese beetle, Popillia japonica Newman, eggs. The effectiveness of each insecticide at controlling Japanese beetle grubs, when applied at different times during the growing season, also was measured. Isofenphos and diazinon significantly reduced both ant numbers and white grub egg predation, whereas imidacloprid and one halofenozide treatment did not significantly impact either measurement. A second halofenozide treatment significantly reduced white grub egg predation. Isofenphos and diazinon were ineffective at controlling Japanese beetle grubs when applied in June but were highly efficacious when applied in August. Evidence of enhanced biodegradation was found in plots that received both June and August applications of diazinon. Both June and August applications of imidacloprid and halofenozide provided good control of white grubs.     

Dispersal of Steinernema glaseri (Nematoda: Steinernematidae) in adult Japanese beetles, Popillia japonica (Coleoptera: Scarabaeidae)

Japanese beetle adults, Popillia japonica, can become infected with and disperse the entomopathogenic nematode, Steinernema glaseri, under laboratory and field conditions. After a 24-h exposure to 10 000 infective juveniles/20 adult beetles, 45% of the beetles died within 4 days post-treatment, but only 59% of these were infected with the nematode. Corresponding control mortality was 6.5%. An average of 238 infective juveniles were produced/beetle. Beetles exposed to 4000 and 10 000 infectives/10 adults carried with them an average of 17 and 59 infectives/adult on external body surfaces respectively. When beetles that had been exposed to 4000 infectives/20 adults were transferred to, and held in, cages containing soil for 2 weeks, up to 89% of the adults died, as did 74% of the P. japonica larvae that were subsequently placed in the cages. When adults that had been exposed to 50 000 infectives/250 beetles in moist sand for 16 h were released into screened cages in the field at soil temperatures of over 25 C, the soil beneath 83% of the cages tested positive for the nematode, using Galleria mellonella larvae as bait, 2 weeks after releasing the beetles. No nematodes were detected in control plots. The potential of infected adult P. japonica for dispersing S. glaseri by flight was investigated by exposing adults to 50 000 infectives/250 beetles, marking and releasing them in the field and recapturing them in lure-baited Japanese beetle traps. Less than 1% of the treated beetles were recaptured, but 33% of these had one or more nematodes in their hemocoels. Accordingly, this approach does not appear to be feasible for large-scale augmentation and dispersal of the nematode using currently developed methods of infection. If improvements in mass-inoculation methods can be made that enable a rapid high percentage of infection while still permitting flight, this concept could be employed to establish new foci of infection or for the introduction of other species of nematodes.     

Virulence of entomopathogenic nematodes to pecan weevil larvae, Curculio caryae (Coleoptera: Curculionidae), in the laboratory

The pecan weevil, Curculio caryae (Horn), is a key pest of pecans in the Southeast. Entomopathogenic nematodes have been shown to be pathogenic toward the larval stage of this pest. Before this research, only three species of nematodes had been tested against pecan weevil larvae. In this study, the virulence of the following nine species and 15 strains of nematodes toward fourth-instar pecan weevil was tested: Heterorhabditis bacteriophora Poinar (Baine, HP88, Oswego, NJ1, and Tf strains), H. indica Poinar, Karunakar & David (original and Homl strains), H. marelatus Liu & Berry (IN and Point Reyes strains), H. megidis Poinar, Jackson & Klein (UK211 strain), H. zealandica Poinar (NZH3 strain), Steinernema riobrave Cabanillas, Poinar & Raulston (355 strain), S. carpocapsae (Weiser) (All strain), S. feltiae (Filipjev) (SN strain), and S. glaseri (Steiner) (NJ43 strain). No significant difference in virulence was detected among nematode species or strains. Nematode-induced mortality was not significantly greater than control mortality (in any of the experiments conducted) for the following nematodes: H. bacteriophora (Baine), H. zealandica (NZH3), S. carpocapsae (All), S. feltiae (SN), S. glaseri (NJ43), and S. riobrave (355). All other nematodes caused greater mortality than the control in at least one experiment. Heterorhabditis megidis (UK211) but not H. indica (original) displayed a positive linear relationship between nematode concentration and larval mortality. Results suggested that, as pecan weevil larvae age, they may have become more resistant to infection with entomopathogenic nematodes.     

Toxicity of two ecdysone agonists, halofenozide and methoxyfenozide, against the multicoloured Asian lady beetle Harmonia axyridis (Col., Coccinellidae)

Abstract: The insecticidal activity of two ecdysone agonists, methoxyfenozide (RH-2485) and halofenozide (RH-0345), was tested against last-instar larvae of the natural predator Harmonia axyridis (Col., Coccinellidae). In addition, the relative weight gain of the larvae after application was followed. Both products proved to be equally toxic at concentrations of 25, 50 and 100 mg/l. The ecdysteroidal activity of the compounds caused premature induction of larval moulting, cessation of feeding and incomplete pupation in affected larvae. Although, compared with previous results with methoxyfenozide and halofenozide in target pests such as the Colorado potato beetle, Leptinotarsa decemlineata , these compounds caused mortality only after application at relatively high concentrations.     

Efficacy of soil treatments of entomopathogenic nematodes against the larvae, pupae and adults of Tuta absoluta and their interaction with the insecticides used against this insect

The efficacy of soil treatments of three native entomopathogenic nematodes (Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora) against Tuta absoluta larvae, pupae and adults was determined under laboratory conditions. The effect of three insecticides commonly used against T. absoluta, in the survival, infectivity and reproduction of these nematode strains was also evaluated. When dropped into soil to pupate, soil application of nematodes resulted in a high mortality of larvae: 100, 52.3 and 96.7 % efficacy for S. carpocapsae, S. feltiae and H. bacteriophora respectively. No mortality of pupae was observed and mortality of adults emerging from soil was 79.1 % for S. carpocapsae and 0.5 % for S. feltiae. The insecticides tested had a negligible effect on nematode survival, infectivity and reproduction. No sublethal effects were observed. Infective juveniles that survived to insecticide exposition were able to infect Galleria larvae with no significant differences from the control. The Galleria larvae affected by the three insecticides tested served as suitable hosts for the infection and reproduction of the nematodes. These results suggest that larvae of T. absoluta, falling from leaves following insecticide application, could be suitable hosts for nematodes, thereby increasing their concentration and persistence in the soil.     

Susceptibility of Sap Beetles (Coleoptera: Nitidulidae) to Entomopathogenic Nematodes

Nitidulid beetles (Coleoptera) are considered to be serious pests of date palms throughout the world. They attack ripe fruit, causing it to rot, and damage is reflected in both reduced yield and lower fruit quality. The present study was aimed at an evaluation of the susceptibility to different sap beetles to entomopathogenic nematodes. We further tested nematode efficacy in pots filled with soil infested by third instar larvae of the two beetle species. In Petri dish assay, mortality levels of Carpophilus humeralis and C. hemipterus exposed to Heterorhabditis sp. IS-5 strain indicated that the latter is less susceptible to nematode infection. Exposure of both sap beetle species to different nematode strains gave moderate levels of mortality (35-65%) with the heterorhabditid strains HP88, IS-5 and IS-25. The IS-12 strain of Heterorhabditis sp. showed poor virulence (<35% mortality) against larvae of C. humeralis as well as larvae and pupae of C. humipterus. The nematode species S. riobrave showed moderate virulence (35-65%) mortality to larvae and pupae of S. humeralis as well as to larvae of C. hemipterus . Exposure of C. hemeralis to different concentrations of Heterorhabditis sp. IS-5 in pots containing soil resulted in high mortality (>65%). In contrast, the lower concentrations (500 and 1000 nematodes/pot) caused low mortality (35%) of C. hemipterus . Other heterorhabditid strains caused 95-100% mortality of C. humeralis in pot assay. The HP88 strain of H. bacteriophora and the Tx strain of Steinernema riobrave showed poor effectiveness. Incubation of different nematode strains with the C. humeralis larvae at high temperature (32 C) resulted in an increase in insect mortality with the IS-12 and IS-21 strains. Reduced mortality was recorded with the HP88 strain treatment at the higher temperature. The IS-5 and IS-12 strains were equally effective in all three soil types tested, whereas the IS-19 strain was more effective in the Almog type soil than in the others.     

Evaluation of application technologies of entomopathogenic nematodes for control of the black vine weevil

Black vine weevil, Otiorhynchus sulcatus (F.), is a severe pest of small fruit and nursery crops around the world. These studies were conducted to determine the efficacy of three species of entomopathogenic nematodes (Heterorhabditis marelatus, Heterorhabditis bacteriophora, and Steinernema riobrave) applied in infected host cadavers or as aqueous applications for black vine weevil larval control. Experiments were conducted in the greenhouse and outdoors. Application of three infected host cadavers or 40 infective juvenile nematodes (IJs) /cm2 were made to pots of Impatiens walleriana 5-7 d after larval infestation. Efficacy was assessed at 14 d in the greenhouse and at 14 and 28 d after nematode application in outdoor trials. In the greenhouse, all treatments with the exception the S. riobrave (cadaver and aqueous applications) provided nearly 100% efficacy after 14 d. The S. riobrave applications, although significantly better than the control, only provided 40-70% control and were not included in the outdoor trials. Nematode efficacy was slowed in the outdoor trials particularly in the cadaver applications. In the initial outdoor trial (soil temperatures < 12 degrees C), there were no significant differences between any nematode treatment and the control after 14 d. The nematode efficacy in the initial outdoor trial after 28 d was improved from the 14-d evaluation but not to the level seen in the second trial. In the second outdoor trial, in which soil temperatures were higher (> 12 degrees C), the aqueous applications of H. marelatus and H. bacteriophora provided nearly complete control after 14 d. The cadaver applications also provided nearly complete control in the second outdoor trial after 28 d. Even though the potential total number of IJs estimated per pot was higher in the cadaver-applied treatments, cool soil temperatures apparently delayed or potentially reduced IJ emergence from cadavers resulting in delayed control.     

Entomopathogenic nematodes to control black vine weevil (Coleoptera: Curculionidae) on strawberry.

We investigated the potential of heterorhabditid nematodes to control larvae of the black vine weevil, Otiorhynchus sulcatus (F.), in 2 field experiments in commercial strawberry plantings. In both experiments, nematodes were applied directly onto the straw mulch, or onto the soil after temporary removal of the mulch. Heterorhabditis marelatus Lui & Berry (Rhabditida: Heterorhabditidae) reduced numbers of weevil larvae and the percentage of plants infested in both experiments, irrespective of straw removal. In the 1st field experiment, a sponge-packed H. marelatus formulation produced lower numbers of O. sulcatus larvae per strawberry plant (mean O. sulcatus larvae per plant = 0.7) and proportion of infested plants (42%) compared with a vermiculite formulation (mean O. sulcatus larvae per plant = 1.8, proportion infested plants 67%) and an untreated control (mean O. sulcatus larvae per plant = 1.9, proportion infested plants 75%). In the first 2 wk after application, more H. marelatus were found in soil samples collected from plots treated with sponge-packed nematodes, than from plots treated with vermiculite-formulated nematodes. In the 2nd field experiment, sponge-packed formulations of H. bacteriophora Poinar (Rhabditida: Heterorhabditidae) and H. marelatus were tested. H. marelatus caused a reduction in both numbers of weevil larvae (mean O. sulcatus larvae per plant = 0.1) and proportion of infested plants (9%) but H. bacteriophora did not (mean O. sulcatus larvae per plant = 0.45, proportion infested plants 34%). More H. bacteriophora were recovered from soil samples than H. marelatus during the first 7 d of this experiment. However, laboratory studies revealed no difference in the persistence of these 2 nematodes in sand.     

Effectiveness of the entomopathogenic nematode <Emphasis Type="Italic">Steinernema feltiae</Emphasis> in agar gel formulations against larvae of the Colarado potato beetle, <Emphasis Type="Italic">Leptinotarsa decemlineata</Emphasis> (Say.) (Coleoptera: Chrysomelidae)

The entomopathogenic nematode Steinernema feltiae strain Ustinov Russia was used on potato foliage to control larvae of the Colorado potato beetle, Leptinotarsa decemlineata (Say.) (Coleoptera: Chrysomelidae). Nematodes were applied in formulations of agar at 4%, 2%, 1% and 0.5% concentrations and compared to a control application of nematodes in water for nematode survival. Agar formulation significantly improved efficacy by increasing nematode survival through reduction in desiccation when compared to water-based formulation. More than 70% of infective juvenile nematodes (IJs) died after being incubated in the highest concentration of agar for 12 h, while only 8% mortality was recorded at the 1% concentration. Suspension of nematodes in 1% agar gel was shown to be efficacious in both laboratory and greenhouse tests for extension of the nematodes’ survival. Agar formulation droplets dried slower than control droplets by 127.8 min. Leptinotarsa decemlineata mortality significantly increased when insects were exposed to infective juvenile nematodes for four hours after application. In conclusion, the agar formulation enhanced nematode survival by providing a suitable environment thereby delaying dryingand increasing the possibility for nematodes to invade their host on the foliage.     

Infectivity and reproductive potential of the Oswego strain of Heterorhabditis bacteriophora associated with life stages of the clover root curculio,Sitona hispidulus

The infectivity and reproductive potential of the entomopathogenic nematode Heterorhabditis bacteriophora (Oswego strain), at different concentrations, was studied. Seventy to 80.0% mortality to late instar larvae of the clover root curculio, Sitona hispidulus, and 40.0-76.0% mortality to pupae, was observed at concentrations of 15-100 infective juveniles. There were no significant differences in mortality among nematode concentrations. LC(50) levels of 4.0 and 21.4 nematodes were determined for clover root curculio larvae and pupae, respectively. Nematodes did not cause significant mortality to adult or first instar clover root curculio. H. bacteriophora was able to complete its development and reproduce in 74.0-95.0% of clover root curculio late instar larvae and pupae. Reproductive potential in curculio larvae and pupae ranged from 0 to 7040 infective juveniles per host. Larvae exposed to 100 nematodes had a reproductive potential significantly higher than in those larvae exposed to 15 and 50 nematodes. Reproductive potential in pupae decreased with an increased nematode dose, indicating potential crowding effects. Host larval and pupal mass were positively correlated with nematode progeny production.     

Susceptibility of the Colorado Potato Beetle and the Sugarbeet Wireworm to Steinernema feltiae and S. glaseri

In laboratory tests, larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and the sugarbeet wireworm (SBW), Limonius californicus (Mannerheim), were exposed to the nematodes Steinernema feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm² of soil, and the LC₅₀ based on 6-day mortality was 47.5 nematodes/cm²; in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm². CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm² soil caused 59% and 71% mortality, respectively, of late-fourth-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 weeks after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.     

Laboratory Evaluation of Seven Pakistani Strains of Entomopathogenic Nematodes Against a Stored Grain Insect Pest, Pulse beetle Callosobruchus chinensis (L.)

Seven Pakistani strains of entomopathogenic nematodes belonging to the genera Steinernema and Heterorhabditis were tested against last instar and adult stages of the pulse beetle, Callosobruchus chinensis (L.). These nematodes included Steinernema pakistanense Shahina, Anis, Reid and Maqbool (Ham 10 strain); S. asiaticum Anis, Shahina, Reid and Rowe (211 strain); S. abbasi Elawad, Ahmad and Reid (507 strain); S. siamkayai Stock, Somsook and Reid (157 strain); S. feltiae Filipjev (A05 strains); Heterorhabditis bacteriophora Poinar (1743 strain); and H. indica Poinar, Karunakar and David (HAM-64 strain). Activity of all strains was determined at four different nematode densities in Petri dishes and in concrete containers. A significant nematode density effect was detected for all nematode species tested. Overall, Heterorhabditis bacteriophora, S. siamkayai, and S. pakistanense were among those that showed the highest virulence to pulse beetle larvae and adults. For all nematode species, the last larval stage of the pulse beetle seems to be more susceptible than the adult. LC(50) values in Petri dish and concrete containers were 14-340 IJs/larvae and 41-441 IJs/larvae, respectively, and 59-1376 IJs/adult and 170-684/adult, respectively.     

Multiple-species natural enemy approach for biological control of alfalfa snout beetle (Coleoptera: Curculionidae) using entomopathogenic nematodes

Multiple-species natural enemy approach for the biological control of the alfalfa snout beetle, Otiorhynchus ligustici (L.) (Coleoptera: Curculionidae), was compared with using single-species of natural enemies in the alfalfa ecosystem by using entomopathogenic nematodes with different dispersal and foraging behaviors. Steinernema carpocapsae NY001 (ambush nematode), Heterorhabditis bacteriophora Oswego (cruiser nematode), and Steinernema feltiae Valko (intermediate nematode) were applied in single-species, two-species combinations, and one three-species combination treatments at 2.5 x 10(9) infective juveniles per hectare. All nematode species persisted for a full year (357 d). S. carpocapsae NY001 protected the plants from root-feeding damage better than H. bacteriophora Oswego but allowed for higher larval survival than all other nematode treatments. S. feltiae Valko protected the plants better than H. bacteriophora Oswego and controlled alfalfa snout beetle larvae better than S. carpocapsae NY001. H. bacteriophora Oswego allowed for similar root damage compared with control plots but reduced larval populations better than S. carpocapsae NY001. The combination of S. carpocapsae NY001 and H. bacteriophora Oswego provided significantly better protection for the plants than the control (unlike H. bacteriophora Oswego alone) and reduced host larva survival more than S. carpocapsae NY001 alone. The combination S. feltiae Valko and H. bacteriophora Oswego could not be statistically separated from the performance of S. feltiae Valko applied alone.     

Compatibility of entomopathogenic nematodes with fipronil

The survival and infectivity of infective juveniles (IJs) of three species of entomopathogenic nematodes, Steinernema carpocapsae Weiser, S. arenarium (Artyukhovsky) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), were determined after exposure to different concentrations (250, 500, 1000 and 2000 ppm) of fipronil, an insecticide acting on the GABA receptors to block the chloride channel. Heterorhabditis bacteriophora was very tolerant to all concentrations of fipronil, with the highest mortality of 17% being observed at 2000 ppm of fipronil after 72 h exposure. Steinernema carpocapsae showed a similar response, with the highest mortality of 11.25% of IJs being observed after 72 h exposure to 2000 ppm of fipronil. Steinernema arenarium was, however, more sensitive to fipronil, and at 2000 ppm mortality rates of 94.6% and 100% were observed after 24 and 72 h, respectively. Fipronil had negligible effects on the infectivity of the three nematode species tested. The IJs which survive exposure to all concentrations of fipronil tested can infect and reproduce in Galleria larvae. The moderate effects on entomopathogenic nematodes of a lower fipronil concentration (250 ppm) and the field rates (12-60 ppm) of fipronil used as insecticide, suggest that direct mixing of entomopathogenic nematodes and fipronil at field rates is a viable integrated pest management option.     

Survival of adult Tiphia vernalis (Hymenoptera: Tiphiidae) after insecticide, fungicide, and herbicide exposure in laboratory bioassays

Tiphia vernalis Rohwer is a hymenopteran ectoparasitoid of Japanese beetle, Popillia japonica Newman, larvae. The adult wasps feed on nectar or honeydew between mid-April and late June. Adults may contact pesticides when landing on foliage or when females hunt for grubs in the soil. The lethal effect of nursery, turf, and landscape pesticides was determined by exposing wasps to treated foliage in the laboratory. Pesticides tested at labeled rates were the insecticides bifenthrin, carbaryl, chlorpyrifos, halofenozide, and imidacloprid; the herbicides oryzalin, pendimethalin, and a combination product with 2,4-D, dicamba, and mecoprop (multiherbicide); and the fungicides chlorothalonil and thiophanate-methyl. During 2001 and 2002, male and female T. vernalis were exposed to pesticides by using turf cores. For both years, bifenthrin, chlorpyrifos, and imidacloprid treatments lowered adult survival relative to the control, but halofenozide had minimal effect on mortality of males and females. More males than females died after exposure to carbaryl treatments. Survival of females was not reduced by exposure to herbicides or fungicides. Females were apparently more tolerant of pesticides than males. Mortality of males in response to herbicides and fungicides was more variable than for females; in 2002 trials, male mortality was higher after exposure to multiherbicide, oryzalin, pendimethalin, and thiophanate-methyl than the control. The fungicide chlorothalonil did not increase mortality of males or females in either year. Sublethal effects were not evaluated. The study indicates the choice of pesticide may be important for conserving T. vernalis in nursery, landscape, and turf settings.