Nematode Mortality Research Articles

Effects of Plant Leaf Extracts on Egg-Masses Hatching and Juveniles Mortality of the Root-Knot Nematode, Meloidogyne Javanica

The effects of plant extracts from fresh leaves of five different plants; Acasiaarabica, Ziziphusspina christi, Eucalyptus camaldulensis, Lawsonia inermis andDalbergia sissoo were evaluated against egg-masses hatching and juvenilemortality of root-knot nematode, Meloidogyne javanica under laboratory conditions.Results revealed that, all treatments extracts had significantly (P < 0.05) reduced inthe hatching of egg-masses. The maximum reduction occurred in Acasia arabicawith the concentration (S) was (97.13%) and the concentration (S/2) was (89.99%),whereas the minimum reduction caused by Ziziphusspina christi with theconcentration (S) was (45.49%) and the concentration (S/2) was (24.63%). Thesame effects of plant extracts against M. javanica juveniles, the most mortality ofsecond stage juveniles was observed in leaf extracts of Acasia arabica, andDalbergiasissoo with the concentration (S) was (100%) as regarding to and theconcentration (S/2) was (100%) in Dalbergia sissoo, while the least in Ziziphusspinachristi with the both concentrations S and S/2 (17.0 and 5.33%), respectively.

Evaluation of botanical and chemical products for the control of foliar nematodes Aphelenchoides fragariae

Foliar nematodes Aphelenchoides spp. Pose a serious threat to floriculture by causing significant economic losses in home gardens, production nurseries and arboretums, and threatening precious germplasm collections of many ornamental plants. Control of foliar nematodes has become difficult due to the loss of nematicides following the implementation of the U.S. Food Quality Protection Act. Herein, we used a three-stage approach to evaluate 24 products for their potential to control foliar nematodes Aphelenchoides fragariae in hosta. We first performed a direct contact assay in well-plates where A. fragariae nematodes were exposed to the aqueous suspension of high (2-fold dilution) or low (20-fold dilution) concentration of the test products. The products causing 100% nematode mortality at the low concentration were then tested through a drench application for their effectiveness against foliar nematodes in soil, followed by a leaf-disc test to determine their efficacy against nematodes in leaves as a spray application. Of the 24 products, Ammonia, Clorox, grapefruit seed extract, KMnO4, NaDCC, Nemakill, Pylon and ZeroTol caused 100% nematode mortality in aqueous suspension at 20-fold dilution. Drench application of Ammonia, Clorox, KMnO4, NaDCC and ZeroTol reduced over 85% and over 75% A. fragariae population in soil 7 and 42 days after treatment, respectively. Spray application of ZeroTol could reduce over 70% A. fragariae population in leaf discs, whereas Ammonia, Clorox, KMnO4 and NaDCC caused about 50% reduction. Pylon (24% chlorfenapyr) and Nemakill (32% cinnamon oil, 8% clove oil, 15% thyme oil mixture) showed 100% mortality of A. fragariae in all three types of tests, and thus have great potential to serve as effective alternatives to manage foliar nematodes in floriculture.

Fly ash effect on hatching, mortality and penetration of root-knot nematode (Meloidogyne incognita) in pumpkin roots

An experiment was conducted to observe the effect of fly ash on hatching, mortality and penetration of root-knot nematode (Meloidogyne incognita) in pumpkin roots. For hatching experiment different fly ash-extract concentrations (5, 10, 20, 30, 40, and 50%) were prepared. Hatching was significantly reduced in all concentrations, maximum being at 50% concentration. The mortality (%) of juveniles was observed in 1, 2, 3, 4, 5, 6 and 7th days with different levels (5, 10, 20, 30, 40 and 50 %) of fly ash-extract. All the levels were found harmful to juveniles. As the level was increased, the killing percentage of juveniles was also increased. Highest mortality was observed in 7th day with 50% level.For the penetration experiment, fly ash was mixed with soil to prepare different concentrations (5, 10, 20, 30, 40, and 50%). Seeds of pumpkin were grown in coffee cups filled with different mixtures. At two leaf stage, seedlings were inoculated with 2000 larvae. The penetrated larvae in roots were observed after 1, 2, 3, 4, 5, 6 and 7 days. Root penetration was found inversely proportional to concentration. Significant results in the suppression of nematode penetration were noted up to 40% concentration. However, none of the juveniles was penetrated at 50% concentration.International Journal of Environment Vol.5(3) 2016, pp.66-73

Антинематодна активність метаболітів, що продукуються грунтовими стрептоміцетами

To study in vitro the antinematicide activity of soil streptomycetes metabolite and bioformulations based on them against root-knot, cyst and leaf nematodes of species. Action of streptomycetes metabolites and their bioformulations were determined in vitro against larvae at two age of root-knot nematode M incognita (Kofoid & White, 1919) Chitwood 1949 and sugar beet cyst nematode H. schachtii A. Schmidt 1871, and leaf nematodes ofAphlenchoides genus by cultivation them in solutions of biomass ethanol extracts separate individual components metabolites and bioformulations during 24 hours. Nematicide and nematistatic effects of the substances were evaluated by the change in the motility activity of the nematodes. Soil streptomycetes S. violaceus IMV Ac-5027, S. averinitilis IMV Ac-5015 and metabolite bioformulations based on them (Violar, Aver- com and Avercom-nova, respectively) showed significant nematicidal activity against plant pathogenic nematodes M incognita and H. schachtii. The biomass extracts of S. avermiti- lis IMV Ac-5015 and S. violaceus IMV Ac-5027 caused 100 % death of nematodes, and S. netropsis IMV Ac-5025 caused only 75 % mortality during 24 hours of action. Using an antibiotic complex from S. violaceus IMV Ac-5027 was divided on six fractions that were different from the avermectin complex. Purified fractions of individual antibiotic complex of S. violaceus IMV Ac-5 027 have a negative impact against the root-knot nematode M incognita. The highest nematicidal activity showed fractions #4 and #5 since their efficiency was over 90 % after a 0.5 hours of action. Nematicidal efficiency of fractions ## 1, 2, 3 and 6 remained between 72.6-86.2 % during 24 hours of action. Fractions 4 and 5 showed high nematicidal effectiveness against leaf nematodes of Aphelenchoides genus where 90-95 % level of helminthes death was observed after 4 hours of action. Among created complex metabolite bioformulations Avercom-nova was the most effective which caused 100 % mortality of nematodes M incognita and H. schachtii after 24 hours of action. Bioformu- lation Violar caused 96.6-96.8 and 95.2-97.0 % of death of nematodes M incognita and H. schachtii, after 24 hours of action. Phytovit based on S. netropsis IMV Ac-5025 showed low nematicide activity against of nematodes, which did not exceed 15.2-18.4 % of their death after 24 hour of action. Bioformulations based on streptomycetes metabolites did not inferior to chemical insecticide Konfidor Maxi, which caused the death of 93.3-94.6 % nematodes at doses recommended by the manufacturer. Soil streptomycetes S. violaceus IV Ac-5027 and S. avermitilis IMV Ac-5015 are promising producers for creation of bioformulations with nematicidal activity against plant-parasitic nematode of M incoenita and H. schachtii.

Evidence for the involvement of nematocidal toxins of Purpureocillium lilacinum 6029 cultured on Karanja deoiled cake liquid medium.

In present study, in vitro nematocidal bioassays, FT-IR and HPLC analysis were employed to demonstrate the involvement of toxins of Purpureocillium lilacinum in killing root-knot nematodes (Meloidogyne incognita). During growth study, maximum mycelial biomass (10.52 g/l) in de-oiled Karanja cake medium was achieved on 8th day while complete mortality of nematodes was obtained by 6th day filtrate (FKSM). Maximum production of crude nematocidal toxin was recorded on 7th day suggesting that the toxin production was paralleled with growth of the fungus. The median lethal concentration (LC50) determined for the crude toxin from 6th day to 10th day ranged from 89.41 to 43.21 ppm. The median lethal time (LT50) for the crude toxin of FKSM was found to be 1.46 h. This is the first report of implementing a comparative infra-red spectroscopy coupled with HPLC analysis to predict the presence of nematocidal toxin in the fungal filtrate cultured on Karanja deoiled cake liquid medium.

Effects of different pesticides on virulence and mortality of some entomopathogenic nematodes

Entomopathogenic nematodes (EPNs) have been used against especially soil borne insect pests. EPNs are feasible and attractive for biological control, because of their virulence against various insect pests, host seeking ability, being usable with standard equipment, and long-term efficacy. In addition EPNs can be applied simultaneously with some pesticides. These properties make EPNs ideal biocontrol agent in integrated pest management. In the present study, effects of 4 widely used pesticides (Glyphosate, Chlorpyrifos-ethyl, Captan, Fosetyl-al) on virulence and mortality of three EPN strains (Heterorhabditis bacteriophora Alman, H. bacteriophora HbH and Steinernema carpocapsae DD-136) were examined at 24 and 48 h periods. All strains were able to infect Galleria mellonella larvae averagely above 90 % rate, after 24 and 48 h treatments with all pesticides. However, some of the pesticides showed negative impact on the viability of the strains. Especially, DD-136 and Fosetylal seemed like incompatible, as the mortality rates were significantly higher than control for both 24 and 48 h. The results of the present study showed that it may be possible to use some EPN strains with some pesticides. It is expected that the results of the study will provide useful information for future integrated pest management programs.

Ultrasonic phytosanitation of pinewood nematode infected wood

Pinewood nematode (Bursaphelenchus xylophilus) mortality was investigated after ultrasonic treatment at 20 and 40 kHz frequency. Experiments were conducted with infected small wood specimens that were ultrasonically treated for 1, 3, 5 and 7 hours and two variable temperature conditions, namely, a gradually increasing from ambient to a maximum of 70oC and a decreasing from ambient to a minimum of 5oC. The results revealed that the ultrasonic treatment itself had no significant effect on the nematode mortality at the 5oC level, while at the 70oC level, considerable nematode mortality was observed in short time periods and at 7 hours of sonic exposure it reached 100%. Therefore, certain combinations of timing and frequency of ultrasonic waves and produced heat can be effective in killing pinewood nematodes thus resulting in phytosanitized wood.

Effect of plant extracts on hatching and mortality of rootknot nematode

Effect of plant extracts on hatching and mortality of rootknot nematode

Effect of essential oils on mortality, hatching and multiplication of root-knot nematode, Meloidogyne incognitaand its Impact on plant growth parameters

Essential oil from aromatic plants showed strong nematicidal activity in vitro experiments. Among six tested essential oils, percent juvenile mortality was observed in lemon grass (Cymbopogon citratus), 89, 51 as well as in palmarosa (Cymbopogon martini), 80 and 44 at the doses of 500 and 250 ppm respectively at 12 hour of exposure time. However, maximum mortality percentage was observed in C. citratus oil and it registered cent percent mortality at 500 ppm at 24 hours of exposure time. The hatching in both treatments started by 8th day and steeply increased in 10th day. Essential oils at 5 concentrations drastically reduced the total number of J2, as both essential oils showed more than 50% reduction in hatching over control. The minimum cumulative hatching was observed in 1000 ppm in C. citrates oil. The effect of root-dip treatments of tomato seedlings with C. citratus and C. martini significantly reduced total number of root knot galls/per plant, per cent galled area and soil population as compared to control. The minimum number of M. incognita galls was found in C. citratus at 500 ppm it was significantly different from carbosulfan as well as C. martini treatments. The maximum shoot length was found in C. martini followed by C. citratus and carbosulfan at 500 ppm. All the treatments significantly improved the root length than the inoculated plants but they were not significantly different among themselves.

Effectiveness of Endophytic Bacterial Consortium of Coffee Plant on Mortality of Pratylenchus Coffeae in Vitro

Bacteria live in wild in form of a consortium. Use of microbial consortium tends to give better results than single isolate, because the action of enzyme of each type of microbe can complement each other in order to survive. This study aimed to study the effectiveness of bacterial endophytic consortium from coffee plant on plant growth and mortality of parasitic nematodes in coffee. Isolation of bacteria is conducted by growing the crushed roots, stems and leaves of coffee on 20% TSA media, then testing their hemolysis and hypersensitivity reaction. Selected isolates were tested on their effect on the growth of seedling and Pratylenchus coffeae mortality, as well as their chitinolytic, proteolytic, lipolytic, HCN production, dissolution of phosphate (P) and fixation of nitrogen (N2) abilities. The results showed that from 27 isolates of the consortium, 23 isolates showed negative reaction to hypersensitive test and 9 isolates to hemolysis test. The highest mortality rate was shown by K6 isolate (65.8%). The highest growth was shown by K15 and K 21 isolates while the highest root length by K21 isolate. Further analisys showed that 100% of the isolates could hydrolyze proteases, lipid, and produce HCN, while chitinolytic activity was shown by 78% isolates which could fix N2 and 11% of isolates could dissolve phosphate.

Developing cleaner export pathways for taro in Fiji and Samoa

Samoa and Fiji's Taro industry has undergone scrutiny as the taro exported has been labelled, as of poor quality and covered with pests. To address this problem, the Cleaner Pathway Project looks at improving the supply chain of taro and looking at hot water dipping as a phytosanitary treatment for mites and nematodes. To improve soil fertility, the leguminous plant, Mucuna was planted for six months before planting taro to test for the reduction of the soil's nematode level. During harvest, improved handling techniques and the use of crates to transfer corms from the farm to the pack house were trialled, replacing the usual sacks that were commonly used. Pack house standard have also been developed to ensure that taro is processed and packed to export needs. In addition, trials were conducted to determine a suitable post tailing and topping treatment to prevent fungal infections of corms. Hot water dipping of corms and planting materials were tested at different temperatures to determine mite and nematode mortality on corms and the viability of the planting materials. From the result of some of these trials, we have been able to observe better quality taro and a reduced mite and nematode presence on the corms. The Mucuna trials are currently underway and the taro plants are being monitored on a monthly basis. This project should be able to provide us with alternative ways to improve the taro supply chain and provide better quality taro consignments for export.

CATT: a new and non-chemical pest and nematode control method in strawberry planting stock

As an alternative to MeBr fumigation a 48h Controlled Atmosphere Temperature Treatment (CATT) was developed and scaled up by Wageningen UR in cooperation with the Dutch plant propagating association Plantum. This results in an excellent de-infestation and 99.8 % mortality of the strawberry tarsonemid mite (Phytonemus pallidus). This non-chemical and sustainable method provides a healthy production of highly qualified strawberry runners in the field. From 2009 CATT is up scaled to a commercial level and widely applied by Dutch nurseries. In 2011 this CATT method was successfully modified to eradicate also the root knot nematode Meloidogyne hapla (>99.7% mortality), which was not effectively controlled by MeBr fumigation. For an effective killing of the root knot nematodes, temperature must be raised to 40 oC. In several experiments the optimum conditions for a high mortality of both tarsonemids and nematodes was studied. This leads into an adapted CATT of 20 hours at a temperature of 35 oC and 50 % CO2 followed by 20 hours at a temperature of 40 oC. In 2012 this adapted CATT was successfully upgraded and tested under field conditions. Additional research in 2013 leads to the conclusion that cross infection of plants by the bacterial Q-disease Xanthomonas fragariae during CATT treatment is unlikely

Investigating the Role of the Host Multidrug Resistance Associated Protein Transporter Family in Burkholderia cepacia Complex Pathogenicity Using a Caenorhabditis elegans Infection Model.

This study investigated the relationship between host efflux system of the non-vertebrate nematode Caenorhabditis elegans and Burkholderia cepacia complex (Bcc) strain virulence. This is the first comprehensive effort to profile host-transporters within the context of Bcc infection. With this aim, two different toxicity tests were performed: a slow killing assay that monitors mortality of the host by intestinal colonization and a fast killing assay that assesses production of toxins. A Virulence Ranking scheme was defined, that expressed the toxicity of the Bcc panel members, based on the percentage of surviving worms. According to this ranking the 18 Bcc strains were divided in 4 distinct groups. Only the Cystic Fibrosis isolated strains possessed profound nematode killing ability to accumulate in worms’ intestines. For the transporter analysis a complete set of isogenic nematode single Multidrug Resistance associated Protein (MRP) efflux mutants and a number of efflux inhibitors were interrogated in the host toxicity assays. The Bcc pathogenicity profile of the 7 isogenic C. elegans MRP knock-out strains functionality was classified in two distinct groups. Disabling host transporters enhanced nematode mortality more than 50% in 5 out of 7 mutants when compared to wild type. In particular mrp-2 was the most susceptible phenotype with increased mortality for 13 out 18 Bcc strains, whereas mrp-3 and mrp-4 knock-outs had lower mortality rates, suggesting a different role in toxin-substrate recognition. The use of MRP efflux inhibitors in the assays resulted in substantially increased (>40% on average) mortality of wild-type worms.

Selection and Characterization of Bacillus licheniformis MH48 for the Biocontrol of Pine Wood Nematode (Bursaphelenchus xylophilus)

Pine wilt disease (PWD) caused by pine wood nematode, Bursaphelenchus xylophilus, has become the most serious threat to pine trees in Korea. This study was subjected to investigate effective biological control agent against PWD. To select nematocidal bacteria against PWD, Bacillus licheniformis MH48 was selected among five bacteria due to its high nematocidal potential. B. licheniformis MH48 was tested for cell growth and protease activity to evaluate its nematicidal potential. In the B. licheniformis MH48, cell numbers were highest three days after incubation, while protease activity was highest after seven days. In the effect of different concentrations of B. licheniformis MH48 culture broth against B. xylophilus, 20% concentration of culture broth showed approximately 80% of pine wood nematode mortality compared to the control. Especially, pine wood nematode`s cuticle layers were degraded two days after treatment of B. licheniformis MH48 culture broth. The present study suggests that B. licheniformis MH48 can be one of the potential biocontrol candidates against pine wood nematode due to its ability to produce protease.

Microbiota from Meloidogyne exigua egg masses and evidence for the effect of volatiles on infective juvenile survival

Egg masses ofMeloidogyne exiguafrom coffee plants are subjected to a range of microbial populations and these resident soil organisms in the egg masses may affect nematode communities. The incidence of fungi and bacteria inM. exiguaegg masses was investigated and the toxic effect of their volatile organic compounds (VOCs) was tested on second-stage juveniles (J2). Bacteria and fungi were isolated from egg masses on coffee root and identified to species. The nematicidal activity of VOCs from bacterial and fungal strains was tested againstM. exiguainin vitroexperiments. Several bacterial and fungal strains were found inM. exiguaegg masses and produced VOCs that were toxic toM. exiguaJ2. Bacterial strains induced more nematode mortality compared with fungal strains. The continued colonisation of fungi and bacteria inM. exiguaegg masses occurred during the year and their VOCs reduced the viable inocula ofM. exiguaand should be explored as biocontrol agents.

초산과 젖산 혼합액에 의한 수출용 심비디움 검역선충 Bursaphelenchus xylophilus의 방제 효과

The mixture (MX) of acetic acid (AA) and lactic acid (LA) was examined for its effectiveness in the control of the pine wood nematode Bursaphelenchus xylophilus contaminated in cymbidium culture medium. Nematode mortality in vitro was nearly 100% in AA and MX at the concentrations of 5.0-1.0% (pH 2.6 - 4.2) and in LA only at 5.0% (pH 3.5), but lowered at concentrations of 0.5-0.1% (pH 5.1-6.9) more significantly in LA than AA and MX. MX of most concentrations caused higher nematode mortality than the average response to AA and LA. All treatments of MX (0.5% and 0.25%), fosthiazate (standard and double concentrations) and culture dilution of Paenibacillus polymyxa GBR-1 (colony-forming units/ml) reduced significantly the nematode populations in the cymbidium culture medium, compared to non-treatment control, with no significant difference among the treatments. No phytotoxicity occurred in all treatments. pH of the medium with the time after treatment and growths of 2-year-old cymbidium were not significantly different among treatments. Considering the safety and price of the organic acids, use of MX in the processes for culturing cymbidium may be a practically reliable and eco-friendly way in the control of the quarantine nematode in cymbidium.

Biological Control of Meloidogyne hapla Using an Antagonistic Bacterium

We examined the efficacy of a bacterium for biocontrol of the root-knot nematode (RKN) Meloidogyne hapla in carrot (Daucus carota subsp. sativus) and tomato (Solanum lycopersicum). Among 542 bacterial isolates from various soils and plants, the highest nematode mortality was observed for treatments with isolate C1-7, which was identified as Bacillus cereus based on cultural and morphological characteristics, the Biolog program, and 16S rRNA sequencing analyses. The population density and the nematicidal activity of B. cereus C1-7 remained high until the end of culture in brain heart infusion broth, suggesting that it may have sustainable biocontrol potential. In pot experiments, the biocontrol efficacy of B. cereus C1-7 was high, showing complete inhibition of root gall or egg mass formation by RKN in carrot and tomato plants, and subsequently reducing RKN damage and suppressing nematode population growth, respectively. Light microscopy of RKN-infected carrot root tissues treated with C1-7 showed reduced formation of gall cells and fully developed giant cells, while extensive gall cells and fully mature giant cells with prominent cell wall ingrowths formed in the untreated control plants infected with RKNs. These histopathological characteristics may be the result of residual or systemic biocontrol activity of the bacterium, which may coincide with the biocontrol efficacies of nematodes in pots. These results suggest that B. cereus C1-7 can be used as a biocontrol agent for M. hapla.

CATT AS A SUSTAINABLE METHOD FOR DISINFESTATION OF STRAWBERRY MOTHER PLANTING STOCK

From 2009 Controlled Atmosphere Temperature Treatment (CATT) is scaled up to a commercial level and widely applied by Dutch producers of strawberry (Fragaria × ananassa) mother planting stock. CATT is a non-chemical and sustainable method to disinfest plant material from insect pests. Frigo plants are treated after storage and before planting during 48 h at a temperature of 35°C and 50% CO2. This results in an excellent disinfestation and a mortality of 99.8% of the strawberry tarsonemid mite (Phytonemus pallidus). As a side effect, the two spotted spider mite (Tetranychus urticae) was killed as well. This method provides a healthy production of highly qualified strawberry runners in the field. Recently it was found that also the plant parasitic nematodes Meloidogyne hapla and Pratylenchus penetrans can be considerably reduced by application of CATT. For an effective killing of these nematodes however, temperature must be raised to at least 40°C. In several experiments the optimum for a high mortality of both tarsonemids and nematodes has been studied. This leads to an adapted CATT of 20 h at a temperature of 35°C and 50% CO2 followed by 20 h at a temperature of 40°C. Application of these optimized CATT can prevent further dispersion of Meloidogyne hapla nematodes in the strawberry chain. Until now no harmful irreversible results of this adapted CATT on vitality of mother plants are found but will be checked thoroughly in the field on runner production in further experiments.

Efecto nematicida de extractos de Quassia amara y Brugmansia suaveolens sobre Meloidogyne sp. asociado al tomate en Nicaragua.

El objetivo de este trabajo fue evaluar extractos de hojas de Quassia amara L. (Simaroubaceae) y flores de Brugmansia suaveolens L. (Solanaceae) para determinar su efecto nematicida contra Meloidogyne sp. El estudio se realizo en el Campus Agropecuario de la Universidad Nacional Autonoma de Nicaragua-Leon (UNAN-Leon) en el ano 2012. El material vegetal fue deshidratado, pulverizado y sus compuestos fueron extraidos utilizando como solvente metanol. Este estudio se realizo in vitro, se evaluo la mortalidad de los juveniles de Meloidogyne sp. en segundo instar despues de 12, 24 y 48 horas de exposicion a los extractos. Ademas, estos se aplicaron a plantas de tomate en maceteras bajo condiciones de invernadero, cuantificandose las poblaciones de nematodos a los 25, 50 y 75 dias de exposicion al extracto (DEE). En el experimento in vitro Q. amara y B. suaveolens diluidos al 10%, presentaron los mas altos porcentajes de mortalidad despues de 48 h, alcanzando 89 y 78% de juveniles muertos, respectivamente. En maceteras se evaluo la mortalidad de juveniles, indice de agallamiento (IA) y factor de reproduccion (FR). Los mejores resultados para Q. amara se obtuvieron a los 25 DEE, con un porcentaje de mortalidad de 80%, un IA de 1 en una escala de 0-5 y FR de 0,20. Con B. suaveolens, a los 25 DEE se alcanzo el mayor porcentaje de mortalidad de 71%, un IA de 1,2 y un FR de 0,29. Estos resultados in vitro y en maceteras evidenciaron que ambos extractos poseen propiedades nematicidas, ya que redujeron significativamente (P≤0,05) las poblaciones de nematodos, su reproduccion y el nivel de agallamiento de las raices de tomate.

Compatibility of Biological Control Agents and Agrochemicals to Entomopathogenic Nematodes,Steinernema yirgalemense and Heterorhabditis zealandica

The compatibility of two endemic entomopathogenic nematodes (EPNs) with biological control agents and agro-chemicals, likely to be used in an integrated pest management programme for citrus in South Africa was investigated. This is the first report on the possible negative effect of EPNs against Cryptolaemus montrouzieri, a commercially produced biocontrol predatory insect, used against mealybugs. Bioassays were conducted to determine the susceptibility of the mealybug predatory coccinellid beetle, C. montrouzieri, to both nematode species. Results showed the beetle larvae to be highly susceptible to a concentration of 80 IJ/insect of H. zealandica and S. yirgalemense, obtaining 80 % and 92 % mortality, respectively. Adult beetles were found to be twice as susceptible to S. yirgalemense with 64 % mortality, as to H. zealandica with 30 % mortality recorded. Tolerance of both species of infective juveniles to aqueous solutions of Cyperfos 500 EC®, Cryptogran™, Helicovir™, Nu-Film-P® and Zeba®, for infectivity and survival was evaluated. Heterorhabditis zealandica proved to be highly compatible to all products tested, with no significant increase in nematode mortality. The formulations also did not affect the ability of H. zealandica to infect Tenebrio molitor, after exposure to products over a 24-h period. Significant increase in mortality of S. yirgalemense was recorded after 12 hours of exposure to Nu-Film-P® and Cyperfos 500 EC®, and after 6 hours of exposure to Nu-Film-P®. However, results for S. yirgalemense infectivity showed no decrease in the ability of the nematodes to infect insect hosts. Results indicated that nematodes should possibly be applied before the release of C. montrouzieri in citrus orchards.