Heterorhabditis Heliothidis Research Articles

Irrigation and Use of Entomogenous Nematodes, Neoaplectana spp. and Heterorhabditis heliothidis (Rhabditida: Steinernematidae and Heterorhabditidae), for Control of Japanese Beetle (Coleoptera: Scarabaeidae) Grubs in Turfgrass

Neoaplectana carpocapsae Weiser, N. glaseri Steiner, and Heterorhabditis heliothidis (Khan, Brooks, and Hirschman) require at least 0.64 cm irrigation after spray application to turf to promote establishment into the soil. Experiments were conducted in microplots (15.25-cm-diameter turf with soil plugs) and on dry golf course turf. Applications of N. carpocapsae and H. heliothidis (at 12.35 × 10 nematodes per ha), with irrigation following application and moderate soil moisture, produced 53% and 73% control of Japanese beetle, Popillia japonica Newman, larvae in golf course turf.

Virulence mechanisms of Heterorhabditis heliothidis and its bacterial associate, Xenorhabdus luminescens, in non-immune larvae of the greater wax moth, Galleria mellonella

Short-term (4 h) exposure of monoxenically and axenically cultured, dauer, juvenile Heterorhabditis heliothidis to the haemolymph of non-immune Galleria mellonella neither stimulated nor inhibited haemocyte function or lysozyme activity. It is proposed that the nematodes are not recognized as foreign by these non-self defences and that they allow the host to maintain a sterile, non-competitive environment for X. luminescens. By 6 h post-injection with monoxenic nematodes the number of damaged haemocytes increased as the number of X. luminescens and endotoxin activity increased. Similar results occurred with the injection of X. luminescens into G. mellonella. The bacteria were not harmed by the non-self defences of the haemolymph. Haemocyte damage was attributed to the fatty acids of the lipid A moiety associated with lipopolysaccharide released from X. luminescens in the haemolymph. The amino sugars d-glucosamine and N-acetyl- d-glucosamine decreased [ 32P]lipopolysaccharide binding to insect granular cells at low concentration and enhanced binding at higher concentrations. A mechanism for lectin-mediated binding of lipopolysaccharide to haemocytes is discussed.

Comparative pathogenicity of selected entomogenous nematodes to the hardwood borers, Prionoxystus robiniae (Lepidoptera: Cossidae) and Megacyllene robiniae (Coleoptera: Cerambycidae)

Laboratory evaluations were performed to determine pathogenicity of the entomogenous nematodes, Steinernema feltiae Filipjev (= Neoaplectana carpocapsae Weiser) and Steinernema bibionis (Bovien), to carpenterworm, Prionoxystus robiniae. Likewise, Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) was also evaluated in addition to the aforementioned species against the locust borer, Megacyllene robiniae. The carpenterworm was very susceptible to steinernematid species. Carpenterworm vulnerability to parasitism by S. bibionis decreased during the fifth and sixth instars. S. feltiae proved to be the more pathogenic species in the overall comparison with LD 50's of 1.5 and 3.7 nematodes/larvae for S. feltiae and S. bibionis, respectively. LD 50 values of 11.2, 18.8, and 23.4 nematodes/larva obtained were for S. feltiae, S. bibionis, and H. heliothidis, respectively, against the locust borer. These LD 50's were not significantly different from one another at the 0.05 level.

Field Suppression of Three White Grub Species (Coleoptera: Scarabaeidae) by the Entomogenous Nematodes Steinernema feltiae and Heterorhabditis heliothidis1

Laboratory and field tests were conducted from 1983 to 1985 to evaluate the effectiveness of three entomogenous nematodes in reducing white grub populations infesting grass pasture land scheduled for Christmas tree planting. Nematodes tested were three strains of Steinernema feltiae Filipjev (DD-136, Mexican, and All), Steinernema glaseri (Steiner), and Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann). The white grub complex consisted of three species: Phyllophaga anxia (LeConte), Phyllophaga fusca (Froelich), and Polyphylla comes Casey. In laboratory tests, the different nematode species demonstrated similar virulence, producing grub mortalities of 60-80% in 2-4 d. Field treatment results were highly variable; significant grub population reductions occurred at several treatment rates. Sprays with All strain caused the most consistent grub reductions. Nematodes dispersed through the soil to locate and parasitize white grubs. The highest treatment rates usually did not produce the most significant grub population reductions. Rates ranged from 0.54 to 10.76 x 105 nematodes per m2.

Dispersal of the Entomogenous Nematode Steinernema feltiae (Rhabditida: Steinernematidae) by Infected Adult Insects

A laboratory study determined that Spodoptera exigua (Hubner) adults infected with the entomogenous nematode Steinernema feltiae Filipjev dispersed up to 11 m from the site of infection. After dispersal and death of the host, nematode progeny developed within the moth cadavers, moved into the soil, and infected larvae of S. exigua. No significant difference was observed in either the proportion of pupae and adults infected or the longevity of S. exigua adults infected with S. feltiae (All strain, 16.2 h), S. feltiae (Mexican strain, 15.6 h) or Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) (NC strain, 15.0 h). Dispersal of S. feltiae by infected adult insects may account in part for local and worldwide distribution of this and other entomogenous nematodes.

Potential Role of Nematophagous Microarthropods as Biotic Mortality Factors of Entomogenous Nematodes (Rhabditida: Steinernematidae, Heterorhabditidae)

Potential for nematophagous mites and Collembola to reduce survival of entomogenous nematodes was tested in laboratory studies. The majority of the arthropods tested were observed feeding on Steinernema feltiae Filipjev (Breton strain) and Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) (NC strain) infective stage juveniles. Phoresy of S. feltiae infectives on many of the mites was observed, with infectives forming rafts of tightly packed nematodes on the dorsum of some of the larger mites. Such infectives remained viable and could move off the mite to kill prepupae of the greater wax moth, Galleria mellonella (L.). Only one species of mesostigmatid mite, Gamasellodes vermivorax Walter, was able to complete development on infectives, and survival was poor. An endeostigmatid mite, Alycus roseus Koch, and a collembolan, Hypogastura scotti Yosii, were able to complete development from late-instar nymph to adult and to produce viable eggs on S. feltiae . In laboratory studies, there was a negative correlation between G. vermivorax number and greater wax moth prepupal mortality, demonstrating lossin nematode efficacy caused by predation by the mesostigmatid mite. There was also a significant difference between LD50 estimates obtained when mites were present or absent. Thus, nematophagous micro arthropods are a biotic factor that could limit survival of field-applied entomogenous nematodes.

Steinernematid and Heterorhabditid Nematodes for Control of Larval European Chafers and Japanese Beetles (Coleoptera: Scarabaeidae) in Potted Yew

Four species of entomogenous nematodes [Steinernema feltiae (Filipjev) [=Neoaplectana carpocapsae Weiserl (‘All’ strain), S. glaseri (Steiner), Heterorhabditis heliothidis (Khan, Brooks & Hirschmann), and Heterorhabditis sp. (‘Holland’ strain)] were compared with two insecticides (chlorpyrifos and isofenphos) for control of third- (last-) instar larval Japanese beetles (Popillia japonica Newman) and European chafers [Rhizotrogus majalis (Razoumowsky)] in potted Japanese yew (Taxus cuspidata Siebold & Zuccarini). Efficacy was evaluated 17-21 d after treatment. Heterorhabditis sp. (‘Holland’ strain) at 92 nematodes per cm2 of soil surface and H. heliothidis at 192 nematodes per cm2 provided >90% control of Japanese beetles compared with 71% for chlorpyrifos (9.0 kg [AI]/ha) and 84% for isofenphos (4.5 kg [AI]/ha). S. glaseri provided 84 and S. feltiae 29% control (both at 385 nematodes per cm2). Both nematodes and insecticides were less effective in controlling European chafer larvae. Control with nematodes ranged from 46 to 59% with S. glaseri, H. heliothidis, and Heterorhabditis sp. at 385 nematodes per cm2, whereas S. feltiae at 385 nematodes per cm2 did not significantly reduce larval survival compared with the untreated control. Chemical control of European chafer larvae resulted in reductions of 44 and 62% with isofenphos and chlorpyrifos, respectively.

Use of a trickle irrigation system to distribute entomopathogenic nematodes (Nematoda: Heterorhabditidae) for the control of weevil pests (Coleoptera: Curculionidae) of strawberries

An established trickle irrigation system was used to distribute entomopathogenic nematodes for the control of Otiorhynchus sulcatus and Phlyctinus callosus in a commercial strawberry planting. This technique facilitated the rapid distribution of the nematodes to strawberry plants grown under plastic mulch. Variation in the distribution of nematodes was observed, both within the treatment area and on the soil surface immediately after application. Four weeks after the application of 48 000 and 80 000 infective stage Heterorhabditis heliothidis per plant, weevil survival (mean number of live larvae and pupae) was reduced by 59% and 25% compared with untreated plants.

Susceptibility of mushroom pests to the insect‐parasitic nematodes Steinernema feltiae and Heterorhabditis heliothidis

SUMMARYThe potential of two species of insect‐parasitic rhabditid nematodes (Steinernema feltiae, Heterorhabditis heliothidis) for biological control of mushroom flies was studied in pot trials. Three Diptera that commonly infest mushroom crops were used; the larvae of Megaselia halterata (Phoridae), Heteropeza pygmaea (Cecidomyiidae) and Lycoriella auripila (Sciaridae) were all susceptible to parasitism by both nematode species. Fewer adult phorids and sciarids emerged when compost was nematode‐treated and, for L. auripila, the effects of nematode applications at spawning, casing or on both occasions were compared. Casing treatments were more effective than spawning treatments; little extra benefit was gained from applying the nematodes twice. Populations of paedogenetic larvae of H. pygmaea built up rapidly in untreated compost, but were reduced when S. feltiae was applied, and were eradicated by H. heliothidis. Because they can penetrate insect cuticle, as well as natural body openings, Heterorhabditis spp. may be more suitable than Steinernema spp. for the control of mushroom fly larvae.

Infectivity of Insect-parasitic Nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) for Larvae of Some Manure-breeding Flies (Diptera: Muscidae)

Third-instar larvae of Musca domestica, Ophyra aenescens, Fannia canicularis, and Fannia femoralis were exposed to parasitic nematodes in the laboratory. Four strains of Steinernema feltiae, two of Steinernema bibionis, and one of Heterorhabditis heliothidis were tested on moist filter paper in petri dishes. Considerable variability in infectivity within and among hosts was noted for the different nematode strains. Strains of S. feltiae were more infective than S. bibionis or H. heliothidis, but all could infect the four hosts. F. femoralis was highly resistant to infection by S. bibionis and H. heliothidis. Further tests on chicken manure and fly rearing medium showed that infectivity of several nematodes for M. domestica and F. canicularis larvae was markedly less than on filter paper.

Field tests of insect-parasitic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae) against larvae of manure-breeding flies (Diptera: Muscidae) on caged-layer poultry facilities.

Insect-parasitic nematodes were tested for control of larvae of muscoid Diptera in chicken manure in the field. Applications of 8–9 million nematodes per square meter showed no reduction of Fannia canicularis (L.), Fannia femoralis (Stein), or Muscina stabulans (Fallen) by Heterorhabditis heliothidis (NC strain) or Steinernema feltiae (Mexican strain). Subsequent tests of S. feltiae (All strain) against larvae of Musca domestica L. failed to demonstrate parasitism or reduction of larval numbers due to the nematodes, even when applied to wet manure with host larvae on the surface. Ineffectiveness of nematodes in this habitat is discussed.

THE POTENTIAL OF HETERORHABDITID NEMATODES AS CONTROL AGENTS OF ROOT WEEVILS

AbstractGreenhouse and field trials were done to determine the potential of Heterorhabditis heliothidis (Khan, Brooks and Hirschmann) Poinar (NC19 strain), an undescribed Heterorhabditis sp. (NC447 strain), and Steinernema feltiae Filipjev (A32−6 strain) to control British Columbia populations of black vine weevil (Otiorhyncus sulcatus Fab.) and strawberry root weevil (O. ovatus L.). An outdoor application of H. heliothidis applied at rates of 500 and 5000 nematodes per litre of soil gave significantly better control of black vine weevil larvae on potted, lodgepole pine trees (Pinus contorta Dougl.) than did a diazinon drench. Under greenhouse conditions Heterorhabditis sp. NC447 was the most effective nematode of the three tested against O. ovatus on potted, Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco) and S. feltiae the least effective, at all dose rates tested. A field trial using H. heliothidis against O. ovatus in a forest nursery did not provide a significant degree of weevil control. This lack of control is attributed to the average outdoor temperature (11 °C) during the treatment period, which was below the nematode’s optimum temperature range, and the higher-than-average rainfall.

Susceptibility of the house fly, Musca domestica (Diptera: Muscidae), to the entomogenous nematodes Steinernema feltiae, S. glaseri (Steinernematidae), and Heterorhabditis heliothidis (Heterorhabditidae).

The infectivity of the nematodes Steinernema feltiae, S. glaseri , and Heterorhabditis heliothidis for the larval, pupal, adult stages of the house fly were evaluated under different habitat conditions. Second- and 3rd-instar larvae and adult flies were highly susceptible to S. feltiae and H. heliothidis when hosts were confined in petri dishes containing nematode-treated filter paper. Larvae were not susceptible to S. glaseri , and pupae within puparia were refractory to infection by all 3 species. When 2nd- and 3rd-instar larvae were exposed to nematodes in rearing medium, S. feltiae caused higher mortality (55–61%) than H. heliothidis (11–26%) at the highest dosage of 5,000 nematodes per host. Both S. feltiae and H. heliothidis were more infective for 3rd-instar larvae (21–29%) than for 2nd-instar larvae (2–6%) at this dosage in poultry manure. When adult flies were offered S. feltiae suspensions in a 5% sucrose bait on cotton balls, mortality ranged from 53 to 67% at dose rates ranging from 1,000 to 100,000 nematodes per milliliter of bait.

Encapsulation of Steinernematid and Heterorhabditid Nematodes with Calcium Alginate: A New Approach for Insect Control and Other Applications

The entomogenous nematodes Steinernema feltiae Filipjev (= Neoaplectana carpocapsae Weiser) and Heterorhabditis heliothidis (Khan, Brooks & Hirschmann) were encapsulated in calcium alginate and fed to larvae of Spodoptera exigua (Hubner) in petri dishes. While feeding on the capsules, the larvae released the nematodes. When moisture was present, larval mortality was nearly 100%, but little or no mortality occurred when free moisture was not present. S. feltiae in the capsules survived for 8 months with no detectable loss in survivability or infectivity when stored at 4°C. Capsules coated with a lipid membrane were completely desiccated at 50% RH with no nematode survivors, but at 72% RH, 71.2% of the nematodes were alive after 24 h. Potential use of the capsules containing these nematodes for insect control is discussed.

SUSCEPTIBILITY OF THE LESSER MEALWORM, ALPHITOBIUS DIAPERINUS (COLEOPTERA: TENEBRIONIDAE) TO THE ENTOMOGENOUS NEMATODES STEINERNEMA FELTIAE, S. GLASERI (STEINERNEMATIDAE) AND HETERORHABDITIS HELIOTHIDIS (HETERORHABDITIDAE)

The infectivity of Steinernema feltiae, S. glaseri and Heterorhabditis heliothidis for early-stage larvae, late-stage larvae, pupae and adults of the lesser mealworm were evaluated under different habitat conditions. When confined in petri dishes with nematode-treated filter paper, all beetle stages were highly susceptible to parasitism by S. feltiae, with LD50 values ranging from 9 to 56 nematodes per host Early-stage larvae (LD50 = 26) and pupae (LD50 = 36) were more susceptible than late-stage larvae (LD50 = 1,791) and adults (LD50 = 724) to H. heliothidis. Only adult beetles (LD50 = 714) were susceptible to S. glaseri. Late-stage beetle larvae were more susceptible to S. feltiae in rearing medium (LD50 = 24), broiler litter (LD50 = 2 58) and poultry manure (LD50 = 212) than to H. heliothidis, which caused less than 50% mortality at all dose rates in these substrates. Adults were less susceptible than larvae in these substrates, and mortality only exceeded 50% in litter treated with S. feltiae (LD50 = 971). Late-stage larvae were highly susceptible to both S. feltiae and H. heliothidis in sandy loam and clay soils, with LD50's ranging from 1 to 14 nematodes per larva. Pupal mortality was higher in sandy loam (S. feltiae LD50 = 46, H. heliothidis LD50 = 444) than in clay soil (S. feltiae LD50 = 95, H. heliothidis LD50 = 5,796).

Preliminary laboratory tests with two species of entomophilic nematodes for control of Musca domestica in intensive animal units‡

SUMMARYTwo species of entomophilic nematodes, Heterorhabditis heliothidis (NZ strain) and Steinernema feltiae (Agriotos strain) were tested in the laboratory against immature and adult stages of a strain (G) of Musca domestica with multiple insecticide‐resistance. Both species of nematodes killed larval stages of M. domestica on inoculated filter papers. S. feltiae was the most virulent parasite, and killed >90% of all larval stages at the two highest doses of 25 000 and 50 000 nematodes per 0·5 ml tap water. No puparia were parasitised by either species. There was no parasitism of the larval stages after exposure to chicken manure treated with nematodes. All adult flies were parasitised after they were exposed to bait‐pads previously inoculated with S. feltiae, 93.3% were parasitised by H. heliothidis.

Entomogenous Nematodes as Biological Control Organisms for Ligyrus subtropicus (Coleoptera: Scarabaeidae) in Sugarcane

Five entomogenous nematodes, Steinernema feltia Filipjev (=Neoaplectana carpocapsae Weiser) (All, Mexican, and Breton strains), S. glaseri (Steiner), and Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann) were evaluated in the laboratory against the white grub Ligyrus subtropicus (Blatchley), a serious pest of sugarcane in Florida. When applied in lots of 5,000 nematodes per larva, S. glaseri caused significantly higher mortality to third-instar white grub larvae than the other nematode species tested. Mortality of white grub larvae exposed to 250 S. glaseri nematodes per larva was not significantly different from mortality of larvae with 4,000 nematodes per larva. L. subtropicus appears to be an excellent host for S. glaseri, yielding a mean of 139,576 nematodes per larva when inoculated with 1,000 nematodes per larva. S. glaseri might be used for biological control of L. subtropicus in Florida sugarcane.

Greenhouse Control of the Black Vine Weevil Otiorhynchus sulcatus (Coleoptera: Curculionidae) by Heterorhabditid and Steinernematid Nematodes

We conducted greenhouse tests to determine the effectiveness of the entomogenous nematodes, Heterorhabditis heliothidis, Neoaplectana carpocapsae , and N. glaseri , for control of the black vine weevil, Otiorhynchus sulcatus. H. heliothidis applied to the surface of the soil gave better control against early-instar larvae than did the other nematodes similarly applied. When applied to the soil surface, the three species were equally effective against late-instar larvae but when late-instar larvae were placed 20 cm deep, the best control was achieved with N. glaseri . When injected 5 cm into the soil, the three species showed equal effectiveness against late-instar larvae placed at depths of 5, 10, and 20 cm.

Susceptibility of Anastrepha suspensa (Diptera: Tephritidae) to Steinernematid and Heterorhahditid Nematodes in Laboratory Studies

Significantly more larvae and adults of the Caribbean fruit fly, Anastrepha suspensa (Loew), were infected and killed by the entomogenous nematodes Steinernema feltiae Filipjev (= Neoaplectana carpocapsae Weiser) (All, Mexican, and Breton strains), Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann), and H. bacteriophora Poinar than by S. glaseri Steiner in laboratory studies. Fruit fly pupae were less susceptible to nematode infection. The nematodes multiplied in the host cadavers and began leaving the parasitized hosts within 7 days. The infective-stage nematodes collected from host A. suspensa were infectious to fresh A. suspensa and to Galleria mellonella (L.) larvae.

SUSCEPTIBILITY OF EARLY INSTARS OF SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE) TO HETERORHABDITIS HELIOTHIDIS (NEMATODA: RHABDITIDAE)

Finney et al. (1982) reported on the susceptibility of the 4th to 6th larval instars and pupae of Choristoneura fumiferana (Clemens) to Heterorhabditis heliothidis (Khan, Brooks and Hirschmann). This report describes the susceptibility of the first three larval instars to the nematode. First-instar larvae search for suitable sites where they spin hibernacula in which they molt and overwinter as second-instar larvae. Most third-instar larvae burrow within the balsam fir buds. All these stages occupy cryptic habitats to which delivery of chemical pesticides is a problem. Rhabditid nematodes, which can actively seek out a target insect, may prove a more useful control agent under these circumstances.