Families Steinernematidae Research Articles

Morphological and molecular characterisation of an isolate of Steinernema diaprepesi Nguyen & Duncan, 2002 (Rhabditida: Steinernematidae) from Argentina and identification of its bacterial symbiont.

Entomopathogenic nematodes of the families Heterorhabditidae Poinar, 1976 and Steinernematidae Chitwood & Chitwood, 1937 are used for biological control of insect pests. An isolate of Steinernema diaprepesi Nguyen & Duncan, 2002 was recovered from a carrot field in the locality of Santa Rosa de Calchines (Santa Fe Province, Argentina). These nematodes were characterised based on morphological, morphometric and molecular studies. Their symbiotic bacterium was identified as Xenorhabdus doucetiae Tailliez, Pagès, Ginibre & Boemare, 2006 by sequencing the 16S rRNA gene. The isolate of S. diaprepesi studied exhibits some morphometric differences with the original description, especially in the first generation adults. This is the first description of the species in Argentina.

Prevalence and Diversity of Entomopathogenic Nematodes Spanning a Mean Annual Precipitation Gradient in Pastureland in Oklahoma

Entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae are ubiquitous soil-dwelling obligate parasites of arthropods and are used commercially to suppress soil-dwelling insect pests in agricultural fields. Little is known about diversity of entomopathogenic nematodes in Oklahoma, which is home to 11 ecoregions, nine annual precipitation zones ranging from east to west, and seven soil orders. This study aimed to characterize entomopathogenic nematode communities inhabiting pastureland from different mean annual precipitation zones in Oklahoma. Soil physical parameters and weather data were used to characterize eight pastureland habitats. Soil samples were collected and native entomopathogenic nematodes were isolated using a common bioassay technique. Entomopathogenic nematodes were identified by PCR amplification of individual nuclear ribosomal its regions and sequencing. Six species of Steinernema in the Steinernematidae were isolated, including S. feltiae, S. texanum, S. glaseri., S. carpocapsae, and S. riobrave, and one population of Heterorhabditis bacteriophora in the Heterorhabditidae was recovered. Higher diversity and abundances of entomopathogenic nematodes were found in areas with higher precipitation levels. This study represents the first documentation of these species in OK and indicates a positive correlation between increased entomopathogenic nematodes prevalence as well as diversity and the increase in annual precipitation.

Effect of inoculum age and physical parameters on in vitro culture of the entomopathogenic nematode Steinernema feltiae.

Entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae have a symbiotic association with bacteria which makes them virulent against insects. EPNs have been mass produced using in vivo and in vitro methods, including both solid and liquid fermentation. This study assessed the effect of nematode inoculum age on the production of Steinernema feltiae in liquid, solid and biphasic processes. Several physical parameters were also assessed: the effect of medium viscosity, flask size and aeration speed on the recovery and yield of infective juveniles (IJs). Inoculum age treatments included inoculum liquid cultures that were 7, 14, 21 and 28 days old. Nematodes from the same inoculum were added to one liquid medium (liquid culture), one solid medium with bacteria previously grown in sponge (solid culture) and a variation of the solid medium (a biphasic culture), in which the bacteria were first grown in liquid and, then, soaked into the sponges, with the purpose of providing a more homogeneous bacterial culture before nematode inoculation. Experiments were conducted in Erlenmeyer flasks. Eight treatments were established involving combinations of three variables: two media (with and without 0.2% agar), two flask sizes (250 and 150 ml) and two agitation speeds (180 and 280 rpm). The study showed increases in nematode yield for liquid cultures, but not for solid or biphasic cultures, with the advance of the inoculum age up to 28 days of growth. Furthermore, the addition of 0.2% agar to the liquid medium and increasing the aeration rate by using larger flasks with higher agitation speed may increase nematode recovery and final yield. The experiments were conducted using shake flasks but the results may also be applicable for bioreactors.

Bioformulation of Xenorhabdus stockiae PB09 for controlling mushroom mite, Luciaphorus perniciosus Rack

Bioformulations are the preparations that contain beneficial microorganisms as active ingredients and they may represent a novel alternative to be used in crop protection because of their safety to humans and non-target organisms. Xenorhabdus sp. is an entomopathogenic bacterium that symbiotically associates with nematodes of the family Steinernematidae and has potential to be used in bioformulations due to its pesticide activities. The aim of this study was to determine the efficacy of bioformulations containing Xenorhabdus stockiae PB09 for controlling mushroom mites. The results showed that different Xenorhabdus bioformulations, including wettable powder (WP), liquid cell pellet (LC), and liquid supernatant (LS) were shown to cause very high miticidal activities at 90.25, 86.50, and 92.78 %, respectively. When X. stockiae PB09 bioformulations were stored at room temperature (28 ± 2 °C) and 4 °C for up to 60 days, their viable cells and efficacy were found to decrease. However, storing at 4 °C could relatively maintain both viable cells and efficacy of the bioformulations, especially after 45 days of storage, whereby all the formulations that were kept at 4 °C had 5–10 % and 2–15 times higher miticidal activities and viable cells than that kept at room temperature, respectively. Storing at 4 °C was more appropriate than room temperature for maintaining both viable cells and miticidal activities of all X. stockiae PB09 bioformulations. In conclusion, this study showed that WP and LC formulations were found to be effective and have potentials to be further developed as commercial products for controlling mushroom mites.

Virulence of entomopathogenic nematodes and their symbiotic bacteria against the hazelnut weevil Curculio nucum

AbstractThe virulence of different entomopathogenic nematode strains of the families Steinernematidae and Heterorhabditidae, isolates from Catalonia (NE Iberian Peninsula), and their symbiotic bacteria was assessed with regard to the larvae and adults of the hazelnut weevil, Curculio nucum L. (Coleoptera: Curculionidae). The nematode strains screened included one Steinernema affine, five Steinernema feltiae, one Steinernema carpocapsae, one Steinernema sp. (a new species not yet described) and one Heterorhabditis bacteriophora. The pathogenicity of all the strains of nematodes was tested on larvae and only four of them on adults of the hazelnut weevil. Larval mortality ranged from 10% with S. affine to 79% with Steinernema sp. Adult mortality was higher in S. carpocapsae, achieving 100% adult weevil mortality. The pathogenicity of the symbiotic bacteria Xenorhabdus bovienii, X. kozodoii, X. nematophila and Photorhabdus luminescens was studied in larvae and adults of C. nucum. In the larvae, X. kozodoii showed a LT50 of 22.7 h, and in the adults, it was 20.5 h. All nematodes species except S. affine tested against larvae showed great potential to control the insect, whereas S. carpocapsae was the most effective for controlling adults.

Control of Codling Moth (Cydia pomonella) (Lepidoptera: Tortricidae) in South Africa with Special Emphasis on Using Entomopathogenic Nematodes

In the Western Cape province of South Africa, codling moth (Cydia pomonella) is the most important lepidopteran pest of apples and pears. Currently an integrated pest management (IPM) strategy is followed. However, chemical control still plays an important role in the control of this pest. Entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae have been successfully utilized as biological control agents in classical, conservation, and augmentative insect pest management programmes. In this review different biological control options for control of codling moth are considered, with special emphasis on research being done on the biological control of codling moth using EPNs. To integrate nematodes into an IPM system, it is important to conduct research under local environmental conditions for a specific crop. Application of EPNs against codling moth will target the diapausing larval overwintering population above-ground. Especially for commercial application, the unique environmental conditions in the various production areas need to be assessed to allow for the effective use of various EPN species. Orchard application, onto trees poses its own unique challenges with regard to the inundative application of EPNs. Research on the use of EPNs to control codling moth and obstacles encountered in the success of codling moth control are discussed.

The significance of the tail projections in female entomopathogenic nematodes within the family Steinernematidae.

Several taxonomic studies of the entomopathogenic nematode family Steinernematidae have reported on the minute tail projections on the tail tips of females of the first generation; however, the occurrence and morphology of these traits in other steinernematid species and their taxonomic significance are still unclear. In the present study, the tail projections in females of seven steinernematid species belonging to four phylogenetic clades were examined. The projections are present in all of the tested species and their number and shape is consistent within species but significantly differs among species. It thus seems that these structures may have taxonomic significance at the species level. Based on these results, we suggest that every description of a new species in the family Steinernematidae should contain a precise morphology of the female tail, focused on these projections, using both light and scanning electron microscopy.

Steinernema balochiense n. sp. (Rhabditida: Steinernematidae) a new entomopathogenic nematode from Pakistan.

A new species of entomopathogenic nematode (EPN) named Steinernema balochiense n. sp. belonging to the family Steinernematidae was isolated from Psidium guajava L., rhizophere soil samples of Balochistan, Pakistan. This new species belongs to the carpocapsae group. The new species can be separated from other described species by morphological and morphometrics characteristics as well as DNA sequence polymorphisms. This new nematode species is morphologically characterized by features of infective juveniles (IJ) and males. For the IJ average body length was (455; 415-528) µm, distance from anterior end to excretory pore (35; 32-38) µm, pharynx length (90; 85-98) µm, tail length (44.3; 40-51) µm, D% and E% values (39; 36-44) and (80; 70-92), respectively. For male specimens, the diagnostic characters included total body length (1330; 1135-1632) µm, gubernaculum length (44.4; 40-47) µm, D% (43.8; 40-51) and ratio of GS (63.8; 53-75). Morphological diagnostic traits for new species include the presence of a funnel shaped gubernaculum at the proximal end. S. balochiense n. sp. differs from infective stage juveniles of closest species S. nepalense by having 6 ridges vs 7 ridges in the lateral field. Molecular phylogenetic trees based on sequence of ITS-rDNA, D2D3 regions and the mitochondrial 12S rRNA gene supports the description of this nematode isolate as a new species.

XenorhabdusandPhotorhabdus,Bacterial Symbionts of the Entomopathogenic NematodesSteinernemaandHeterorhabditisand theirin vitroLiquid Mass Culture: A Review

Entomopathogenic nematodes (EPNs) represent an important part of the spectrum of potentially available biological control agents against insect pests. EPNs of the families Steinernematidae and Heterorhabditidae share a mutualistic relationship with bacteria of the genera Xenorhabdus and Photorhabdus, respectively. Current research on the use of EPNs against key pests of fruit crops in South Africa has the ultimate aim of using nematodes on a commercial scale against key insect pests of such fruit crops as deciduous fruit and citrus. For this objective to be realized, nematodes should be mass produced in vitro in liquid culture. A detailed understanding of the biology and behaviour of the nematode species and the associated bacterial symbiont in relation to their mass production is, therefore, required. The long processing time that is required for nematode cultures, combined with the need for an even distribution of fluids and organisms, result in the cultures being extremely vulnerable to contamination. Nematodes experience a very different environment in liquid culture than they do in nature, and a high level of technological knowledge is required for their successful production. Endemic EPNs are not currently commercially produced in South Africa. This review presents an overview of the current knowledge that is available on the bacterial symbionts and on the biology of the two nematode genera. Optimum growth parameters for the bacteria and the nematodes are discussed for endemic nematode isolates that might have the potential to be mass cultured for commercial application.

Survey of entomopathogenic nematodes from the families Steinernematidae and Heterorhabditidae (Nematoda: Rhabditida) in Colima, México

A survey of entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae was conducted in three municipalities on the Pacific coast of the State of Colima, México, to determine their occurrence and recovery frequency and predominant plant species in cultivated and non-cultivated habitats. Nineteen soil samples were collected: seven from non-cultivated habitats and 12 from habitats or areas cultivated mostly with fruit and grain crops and grasses. Of the 19 soil samples, 14 were positive for EPNs; the total prevalence was 73.7%. From the 14 positive soil samples, 12 steinernematid isolates (85.7%) and two heterorhabditid isolates (14.3%) were recovered. Irrespective of the locations, EPNs from the genus Steinernema were recovered from the three municipalities; EPNs from the genera Steinernema and Heterorhabditis were recovered from Armería and Ixtlahuacán. Only steinernematid isolates were recovered from non-cultivated habitats. Most of the isolates were recovered from cultivated habitats, and our results suggest that there is a higher prevalence of EPNs in cultivated soils.

Compatibility between Forficula auricularia and entomopathogenic nematodes to be used in pome fruit pest management

AbstractUse of predators, parasitoids and entomopathogens as biocontrol agents in pome fruit production can lead to more efficient and sustainable pest management programmes. The European earwig (Forficula auricularia Linnaeus [Dermaptera: Forficulidae]) is a major predator of key pests in pome fruit orchards, and entomopathogenic nematodes (EPNs) of the families Steinernematidae and Heterorhabditidae are obligate parasites of a large number of insect species. Therefore, the interaction between earwigs and EPNs can play an important role in pest management programmes. Susceptibility of the European earwig to Steinernema carpocapsae, Steinernema feltiae (Steinernematidae) and Heterorhabditis bacteriophora (Heterorhabditidae) was evaluated. S. carpocapsae was the only tested EPN capable of killing the European earwig. However, the European earwig can detect the presence of S. carpocapsae and therefore avoid nematode‐treated shelters. An earwig deterrent activity in EPN‐killed codling moth larvae that reduces the foraging of European earwig on insect cadavers containing nematodes and allows nematodes to complete their life cycle was also assessed with the three species of nematodes. These findings suggest a positive compatibility between the European earwig and EPNs.

Expression, Purification, and Functional Characterization of Atypical Xenocin, Its Immunity Protein, and Their Domains from Xenorhabdus nematophila.

Xenorhabdus nematophila, a gram-negative bacterium belonging to the family Enterobacteriaceae is a natural symbiont of a soil nematode from the family Steinernematidae. In this study cloning, expression, and purification of broad range iron regulated multidomain bacteriocin called xenocin from X. nematophila (66 kDa, encoded by xcinA gene) and its multidomain immunity protein (42 kDa, encoded by ximB gene) have been done. xcinA-ximB (N′ terminal 270 bp), translocation, and translocation-receptor domain of xcinA, ximB, and its hemolysin domain were cloned, expressed, and purified by single step Ni-NTA chromatography under native conditions. In the functional characterization, neutralization of xcinA toxicity by immunity domain of ximB gene was determined by endogenous assay. Exogenous toxic assays results showed that only the purified recombinant xenocin-immunity domain (10 kDa) protein complex had toxic activity. Atypical cognate immunity protein (42 kDa) of xenocin was fusion of immunity domain (10 kDa) and hemolysin domain (32 kDa). In silico analysis of immunity protein revealed its similarity with hemolysin and purine NTPase like proteins. Hemolytic activity was not observed in immunity protein or in its various domains; however, full-length immunity protein lacking Walker motif showed ATPase activity. Finally, using circular dichroism performed secondary structural analyses of all the recombinant proteins/protein complexes.

SUSCEPTIBILITY OF SPODOPTERA LITTORALIS (BOISD.) TO TREATED ENTOMOPATHOGENIC RHABDITIES, HETERORHABDITIS BACTERIOPHORA AND STEINERNEMA SP. BY DIFFERENT PESTICIDES

ABSTRACT Spodoptera littoralis (Boisd.) is a major plant pest that causes substantial economic losses worldwide especially in vegetable crops. Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are generally considered beneficial organisms which can serve within integrated pest management (IPM) in agroecosystem. The effect of EPNs Steinernema sp. (EBN1e), and Heterorhabdities bacteriophora (EBN10k) that exposed to 11 different chemical pesticides on the cotton leafworm larvae was determined under laboratory condition. Generally, Steinernema sp. (EBN1e strain) exposed to different tested chemical pesticides was more affected on fifth instar larvae of S. littoralis than H. bacteriophora (EBN10k strain). More than 90% of fifth instar larvae of S. littoralis was killed after exposure to EBN1e strain treated with all used chemical pesticides except EPN1e strain treated with chlorfluazuron, thiocyclam and benomyl which caused 75.45, 80.65 and 81.5 % mortality of cotton leafworm fifth larvae respectively. In otherness, the mortality of fifth instar larvae of S. littoralis required to Heterorahbdities strain was less than Steinernema strain treated with different tested chemicals insecticides. There were significant differences in mortality of S. littoralis fifth instar larvae between EBN1e and EBN10k nematodes strains exposed to different chemical insecticides. The EBN1e strain was highly virulent than EBN10k in all treatments. In general, there was significant difference in mortality rates of cotton leafworm larvae required to EPNs concentrations (500IJs and 1000IJs) exposed to different chemicals and between exposure times.

Biocontrol potential of the entomopathogenic nematodes Heterorhabditis bacteriophora and Steinernema carpocapsae on cucurbit fly, Dacus ciliatus (Diptera: Tephritidae)

Entomopathogenic nematodes (EPNs) from the families Steinernematidae and Hererorhabditidae are considered excellent biological control agents against many insects that damage the roots of crops. In a regional survey, native EPNs were isolated, and laboratory and greenhouse experiments were conducted to determine the infectivity of EPNs against the cucurbit fly, Dacus ciliatus Loew (Diptera: Tephritidae). Preliminary experiments showed high virulence by a native strain of Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) and a commercial strain of Steinernema carpocapsae Weiser (Rhabditida: Steinernematidae). These two strains were employed for further analysis while another native species, Steinernema feltiae, was excluded due to low virulence. In laboratory experiments, larvae and adult flies were susceptible to nematode infection, but both nematode species induced low mortality on pupae. S. carpocapsae had a significantly lower LC50 value against larvae than H. bacteriophora in filter paper assays. Both species of EPNs were effective against adult flies but S. carpocapsae caused higher adult mortality. When EPN species were applied to naturally infested fruit (150 and 300 IJs/cm2), the mortality rates of D. ciliatus larvae were 28% for S. carpocapsae and 12% for H. bacteriophora. Both EPN strains successfully reproduced and emerged from larvae of D. ciliates. In a greenhouse experiment, H. bacteriophora and S. carpocapsae had similar effects on fly larvae. Higher rates of larval mortality were observed in sandy loam and sand soils than in clay loam. The efficacy of S. carpocapsae and H. bacteriophora was higher at 25 and 30°C than at 19°C. The results indicated that S. carpocapsae had the best potential as a biocontrol agent of D. ciliatus, based on its higher virulence and better ability to locate the fly larvae within infected fruits.

The effect of different pesticides on reproduction of entomopathogenic nematodes

Entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are generally considered beneficial nematodes. These beneficial nematodes can serve in integrated pest management (IPM) in agro-ecosystems. The effect of chemical insecticides (11 different pesticides) on Steinernema sp. (EBN-1e), and Heterorhabditis bacteriophora (EBN-10k) was determined under laboratory conditions. Generally, EBN-1e Steinernema strain was more tolerant to different tested insecticides than Heterorhabditis strain. The survival of IJs was more than 90% after treatement with Captan, Methomyl, Mancozeb, Benomyl, Trimiltox forte and Diafenthiuron, for EBN-1e nematode strain, while Chlorfluazuron decreased its survival to less than 5%. In contrast, the survival of Heterorahbditis strain was less than the Steinernema strain. There were significant differences in reproduction rates between EBN-1e and EBN-10k exposed to different chemical insecticides. The EBN-1e strain had higher reproduction rate than EBN-10k in all treatments. In general, there was significant difference in reproductive rates between the species concentrations (500 IJs and 1000 IJs) exposed to different chemicals or between exposure times (48 h. and 96 h.)

<i>Insilico</i> Analysis of Novel <i>Relb</i>, <i>Rele</i> and <i>Mazf</i> Toxin-Antitoxin Homolog’s from the Genome of <i>Xenorhabdus </i><i>Nematophila</i>

Xenorhabdus nematophila is a motile gram-negative bacteria belonging to the family Enterobacteriaceae and is a natural symbiont of a soil nematode of family Steinernematidae. The bacterium is essential for effective killing of the insect host and is required by the nematode to complete its life cycle. X. nematophila can be grown under standard laboratory conditions and known to secrete several extracellular products, which include lipase(s), phospholipase(s), protease(s), and several broad spectrum antibiotics as the bacteria enter the stationary phase of their growth cycle and are believed to be secreted in the insect hemolymph. Recently, the genome of X. nematophila has been completely sequenced and annotated version is available in the NCBI database. In this study we have extensively analyzed bioinformaticaly the genome of X. nematophila with NCBI server (www.ncbi.nlm.nih.gov). Our results showed the presence of relB, relE, and mazF toxin-antitoxin homolog's at different loci in the genome. Later, various genes present in these loci were studied for phy- logenetic as well as physiochemical analysis. Promoter analysis of each module has been done to know the various tran- scription factors involved in their transcription.

Occurrence of entomopathogenic nematodes of the family Steinernematidae and Heterorhabditidae in orchards chemically protected and unprotectedWystępowanie nicieni owadobójczych z rodziny Steinernematidae i Heterorhabditidae w sadach chronionych i niechronionych chemicznie

The studies on the occurrence and species composition of entomopathogenic nematodes (Steinernematidae, Heterorhabditidae) in chemically protected and unprotected were carried out in 2009–2011. Field studies conducted in 2009–2011, in orchards without protection and where chemical treatments were performed evenly, according to recommendations. The aim of this study was to compare the frequency and species composition of entomopathogenic nematodes (Steinernematidae, Heterorhabditidae) in orchards protected and unprotected chemically. Soil samples were collected from selected sites three times (spring, summer, autumn) in the season. Four species of entomopathogenic nematodes three of the families Steinernematidae and Heterorhabditidae were isolated from soil samples. The results of the studies revealed both a higher biodiversity of the nematode species composition as well as their incidence in the enprotected apple orchards.

Control of a new turf pest, Dorcadion pseudopreissi (Coleoptera: Cerambycidae), with the entomopathogenic nematode Heterorhabditis bacteriophora

The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1 × 1 × 1 m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m2 to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6 months.

Short term response of soil microinvertebrates to application of entomopathogenic nematode-infected insects in two tillage systems

Entomopathogenic nematodes (EPN) in the families Steinernematidae and Heterorhabditidae occur naturally in the soil and are produced commercially for the management of soil-dwelling pests. EPN infected cadavers also represent a potential resource for other soil organisms. We examined the short-term (24 h) response in abundance, diversity and community composition of localized soil microinvertebrates to the presence of EPN-infected insect cadavers in no-till and conventional-till maize. We hypothesized that the response of soil microinvertebrates to the EPN-infected cadavers would vary by soil management practices and EPN species. We expected to observe greater numbers and diversity of arthropods in no-till compared with conventional-till soil, and in the vicinity of steinernematid-infected insect cadavers compare to what would be found in the vicinity of heterorhabditid-infected cadavers. 45,606 invertebrates were collected and identified to 134 morphotaxa. Tillage regime accounted for the majority of the variation observed (84.6%), whereas nematode treatment accounted for 7.5%. Taxonomic richness of invertebrates was greater in treatments with Steinernema carpocapsae -infected cadavers than with Heterorhabditis bacteriophora -infected cadavers. Some invertebrates increased in abundance where EPN were applied whereas others decreased, regardless of tillage practice. Applications of Galleria cadavers infected with steinernematids elicited positive responses from two mite taxa, Galumnidae and Scheloribates spp., while negative responses were elicited from three mite (Histiostomatidae, Scheloribates spp., Eupodes spp.), taxa and Entomobryidae (Collembola) in response to applications of Heterorhabditis -infected cadavers.

Potential negative effects on biological control by Sancassania polyphyllae (Acari: Acaridae) on an entomopathogenic nematode species

Sancassania polyphyllae (Acari: Acaridae) is associated with larvae of the white grub, Polyphylla fullo (Coleoptera: Scarabaeidae), and will feed on the infective juveniles of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae which are important biological control agents of soil insect pests. We conducted laboratory studies to determine the potential negative effects this mite species might have on biological control of soil insect pests. Our objectives in this study were to (1) determine the response of S. polyphyllae adult mites to a nematode-killed insects on agar, (2) evaluate the predation by mites on Steinernema feltiae infective juveniles from nematode-killed insects on agar and in soil, and (3) assess predation efficiency of the mite on the infective juveniles in the soil. On agar, we found (1) significantly more adult female mites near or on a nematode-killed Ceratitis capitata (Diptera: Tephritidae) larva than near or on the freeze-killed larva or a bamboo mimic suggesting that a chemical or an odor from the nematode-killed larva attracted the mites, and (2) 10 mites consumed 96% of infective juveniles that emerged from an insect cadaver. In soil with a nematode-killed insect, the average number of infective juveniles recovered was <30 when mites were present, whereas the average number of infective juveniles recovered was >375 when the mites were absent. When the infective juveniles alone were placed in different depths in relation to the mites in the soil column for 4 and 10 days, S. polyphyllae was not as efficient at finding the infective juveniles when they were separated from each other in the soil lending support to the idea that the mites were cueing in on the cadaver as a food resource. Our data suggest that emerging infective juveniles from an insect cadaver in the soil in the presence of S. polyphyllae can adversely affect biological control because of nematode consumption by the mites.