A report of entomopathogenic nematodes from Iran

A survey conducted during 2006 and 2008 showed the presence of both heterorhabditid and steinernematid nematodes in the Arasbaran forests and rangelands, Iran.  Based on both morphological and molecular characteristics, heterorhabditid isolates were identified as Heterorhabditis bacteriophora whereas the steinernematid isolates were identified as Steinerenma carpocapsae, S. bicornutum, S. feltiae, S. glaseri, S. kraussei. For more information on the survey methodology nematode identification techniques read following paper.

Nikdel, M., Niknam, G., Griffin, C.T. and Kary, N.E. 2010. Diversity of entomopathogenic nematodes (Nematoda: Steinernematidae, Heterorhabditidae) from Arasbaran forests and rangelands in north-west Iran.  Nematology 12: 767-773.

Control of white grub Hoplia philanthus with entomopathogenic nematodes

Efficacy of entomopathogenic nematodes including Heterorhabditis bacteriophora CLO51 strain, H. megidis VBM30 strain, H. indica, Steinernema scarabaei, S. feltiae, S. arenarium, S. carpocapsae Belgian strain, S. glaseri Belgian and NC strains was tested against larval pupal stages a white grub, Hoplia philanthus under laboratory and greenhouse conditions. Heterorhabditis bacteriophora, H. megidis and both strains of S. glaseri showed highest virulence against third stage larvae and pupae whereas Belgium strain of S. glaseri showed high virulence against second stage larvae of H. philanthus under laboratory conditions whereas H. bacteriophora, Belgium strains of S. glaseri and S. scarabaei showed high virulence to third stage than second stage larvae of white grubs under greenhouse conditions.

Reference:

Ansari, M.A., Adhikari, B.N., Ali, F. and Moens, M. 2008. Susceptibility of Hoplia philanthus (Coleoptera: Scarabaeidae) larvae and pupae to entomopathogenic nematodes (Rhabditida: Steinernematidae, Heterorhabditidae). Biological Control. 47: 315-321.

Control the annual bluegrass weevil, Listronotus maculicollis with entomopathogenic nematodes

Recently, McGraw et al (2010) demonstrated that field application of three species of entomopathogenic nematodes (Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora) at rate of 2.5 billion nematodes/hectare reduced over 69% population of first generation late instars of the annual bluegrass weevil, Listronotus maculicollis. For more information on the interaction between entomopathogenic nematodes and the annual bluegrass weevil read following literature.

Hello, World!

McGraw, B.A. and Koppenhofer A.M. 2008.  Evaluation of two endemic and five commercial entomopathogenic nematode species (Rhabditida : Heterorhabditidae and Steinernematidae) against annual bluegrass weevil (Coleoptera : Curculionidae) larvae and adults. Biological Control. 46: 467-475.

McGraw, B.A. and Koppenhofer A.M. 2009.  Population dynamics and interactions between endemic entomopathogenic nematodes and annual bluegrass weevil populations in golf course turfgrass. Applied Soil Ecology. 41: 77-89.

McGraw, B.A., Vittum, P.J., Cowles, R.S. and Koppenhofer A.M. 2010.  Field evaluation of entomopathogenic nematodes for the biological control of the annual bluegrass weevil, Listronotus maculicollis (Coleoptera: Curculionidae), in golf course turfgrass. Biocontrol Science and Technology. 20: 149-163.

Control of annual bluegrass weevil, Listronotus maculicollis with entomopathogenic nematodes

It has been reported that the entomopathogenic nematodes including Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora when applied at rate of 2.5 billion infective juveniles/ha can cause 69- 94% mortality of first generation late instars of annual bluegrass weevil, Listronotus maculicollis. Of the 3 species of entomopathogenic nematodes, S. feltiae showed higher virulence against annual bluegrass weevil than the other two nematode species (see McGraw et al., 2010).

Read following research papers for more information on interaction between entomopathogenic nematodes and annual bluegrass weevil, L. maculicollis.

McGraw, B.A., Vittumb, P.J. Cowlesc, R.S.and Koppenhoumlfera, A.M. 2010.  Field evaluation of entomopathogenic nematodes for the biological control of the annual bluegrass weevil, Listronotus maculicollis (Coleoptera: Curculionidae), in golf course turfgrass. Journal Biocontrol Science and Technology. 20: 149 - 163.

A first report of occurrence of entomopathogenic nematodes in Nepal

Recently a survey was conducted to study the occurrence and distribution of entomopathogenic nematodes in Nepal.  Although a total of 276 soil samples were collected from various habitats, entomopathogenic nematode were found only in 29 samples.  Nematodes were isolates using the Galleria-baiting technique (Bedding and Akhurst,1975). Both heterorhabditid and steinernematid nematodes were identified at their species level using both molecular and morphological techniques.  In this survey, the occurrence of only one species of heterorhabditids including Heterorhabditis indica and four described species of steinernematids such as Steinernema abbasi, S. cholashanense, S. feltiae and S. siamkayai were reported for the first time in Nepal (Khatri-Chhetri et al., 2010). Read following literature for more information

Bedding, R.A. and R.J. Akhurst. 1975. A simple technique for detection of insect parasitic rhabditid nematodes in soil. Nematologica. 21: 109-110.

Khatri-Chhetri, H.B., Waeyenberge, L., Manandhar, H.K. and Moens, M. 2010.  Natural occurrence and distribution of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in Nepal. Journal of Invertebrate Pathology. 103: 74-78.

Kill leaf beetles (Altica quercetorum, Agelastica alni and Xanthogaleruka luteola) with Entomopathogenic Nematodes

• The leaf beetles, Altica quercetorum and Agelastica alni are serious pests of urban trees including Quercus sp and Alnus sp, respectively.
• The elm leaf beetle Xanthogaleruka luteola is a serious pest that causes defoliation of eml trees (Ulmus spp.) in North America.
• Adults of these beetles generally feed on leaves by chewing holes through the leaf tissue.
• Larvae skelotonize leaves by feeding on leaf tissues leaving veins and upper epidermis intact.
• Entomopathogenice nematodes including Heterorhabditis megidis, Steinernema carpocapsae and S. feltiae can be used as potential biocontrol agents against different species leaf beetles (read Grewal et al., 2005 for more information).
• It has been shown that both the pre-pupal and pupal stages of A. quercetorum and A. alni are very susceptible to H. megidis when applied in the soil.
• The last instar larvae of X. luteola are highle susceptible to S. carpocapsae when applied to the mulch.

How Entomopathogenic Nematodes kill leaf beetles

• When the infective juveniles are applied to the soil surface or mulch, they start searching for their hosts, in this case leaf beetles grubs.
• Once a beetle grub has been located, the nematode infective juveniles penetrate into the grub body cavity via natural openings such as mouth, anus and spiracles.
• Infective juveniles of Heterorhabditis also enter through the intersegmental members of the grub cuticle.
• Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in grub blood.
• In the blood, multiplying nematode-bacterium complex causes septicemia and kills grubs usually within 48 h after infection.
• Nematodes feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new larvae in the soil.

References: Refer following book to read more about efficacy of entomopathogenic nematodes against leaf beetles

1. Grewal, P.S. Ehlers, R.-U., Shapiro-Ilan, D. (eds.). Nematodes As Biocontrol Agents. CAB publishing, CAB International, Oxon

Kill leafminers (Liriomyza spp.) with Entomopathogenic Nematodes

• Leafminers (Liriomyza spp.) are considered as economically important polyphagous pests of many indoor vegetable crops and flowering plants.

• Vegetable host crops included beans, beet, carrots, celery, cucumbers, eggplants, lettuce, melons, onions, peas, peppers, potatoes, squash and tomatoes.

• Flowering host plants included ageratum, aster, calendula, chrysanthemum, dahlia, gerbera, gypsophila, marigold, petunia, snapdragon, and zinnia.

• Leafminer maggots generally feed on leaf parenchyma tissues by tunneling/mining between the upper and lower epidermal leaf surfaces.

• Adults generally feed on sap exuding from the punctures caused by maggots during mining.

• Infested leaves appear stippled due to the punctures made by leafminers while feeding, mining and oviposition especially at the leaf tip and along the leaf margins.

• Widespread mining and stippling on the leaves generally decreases the level of photosynthesis in the plant leading towards the premature leaf drop reducing the amount of shade, which in turn causes sun scalding of fruits.

• Injuries caused by maggots on the foliage also allow entry of bacterial and fungal disease causing pathogens.

• Life cycle of leafminers contains four stages including egg, maggot, pupa and adult.

• Life cycle can be completed within 15-21 days depending upon the host and temperature.

• Adult females lay eggs in leaf tissues, eggs hatch within 2-3 days into maggots, hatched maggots starts feeding immediately and become mature within 3-4 days. Mature larvae eventually cut through the leaf epidermis and move to the soil for pupation and adults emerge within 3 weeks of pupation in the summer.

• Although, chemical insecticides are generally used to protect foliage from injury caused by leafminers, but development of insecticide resistance among leafminer populations is a major problem.

• Insecticides also are highly disruptive to naturally occurring biological control agents, particularly parasitoids.

• Therefore, biological control agents including Bacillus thuringiensis var. thuringiensis (Bt), parasitic wasps (Diglyphus begina, D. intermedius, D. pulchripes and Chrysocharis parksi) and entomopathogenic nematodes (Heterorhabditis spp, Steinernema carpocapase and S. feltiae) have been considered as alternatives to chemical pesticides.

• For successful control of leafminers, entomopathogenic nematodes can be easily applied in water suspension as spray application on plant foliage.

• Entomopathogenice nematodes including S. carpocapase and S. feltiae when applied at the rate of 5.3 X 108 nematodes/ha can cause over 64% mortality of leafminers but need at least 92% relative humidity.

How Entomopathogenic Nematodes kill leafminers

• When the infective juveniles are applied as spray to plant foliage, they enter the leaf mines through the leaf miner feeding punctures or exit holes made by the adults.

• Once inside the mine the nematodes swim to find a leafminer maggot, nematodes then penetrate into the maggot body cavity via natural openings such as mouth, anus and spiracles.

• Infective juveniles of Heterorhabditis also enter through the intersegmental members of the larval cuticle.

• Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in the maggot blood.

• In the blood, multiplying nematode-bacterium complex causes septicemia and kills maggots usually within 48 h after infection.

For more information on the interaction between entomopathogenic nematodes and leafminers, please read following research and extension publications.

• Hara, A.H., Kaya, H.K., Gaugler, R., Lebeck, L.M. and Mello, C.L. 1993. Entomopathogenic nematodes for biological control of the leafminer, Liriomyza trifolii (Dipt.: Agromyzidae). Entomophaga 38, 359-369.

• Head, J. and Walters, K.F.A. 2003. Augmentation biological control utilising the entomopathogenic nematode, Steinernema feltiae, against the South American Leafminer, Liriomyza huidobrensis. Proceedings of the 1st International Symposium on Biological Control, (Hawaii, USA, 13-18 January 2002). USDA Forest Service, FHTET-03-05, 136-140.

• Olthof, T.H.A. and Broadbent, A.B. 1992. Evaluation of steinernematid nematodes for control of a leafminer, Liriomyza trifolii, in greenhouse chrysanthemums. Journal of Nematology 24, 612.

• Tong-Xian Liu, Le Kang, K.M.Heinz, J.Trumble. 2008. Biological control of Liriomyza leafminers: progress and perspective. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2009, 4, No. 004, 16 pp.

• Williams, E.C. and Walters, K.F.A. 1994. Nematode control of leafminers: Efficacy, temperature and timing. Brighton Crop Protection Conference - Pests and Disease. 1079-1084.

• Williams, E.C. and MacDonald, O.C., 1995. Critical factors required by the nematode Steinernema feltiae for the control of the leafminers Liriomyza huidobrensis, Liriomyza bryoniae and Chromatomyia syngenesiae. Annals of Applied Biology. 127, 329-341.

• Williams, E.C. and Walters, K.F.A. 2000. Foliar application of the entomopathogenic nematode Steinernema feltiae against leafminers on vegetables. Biocontrol Science and Technology 10, 61-70.

Kill Western Flower Thrips with Entomopathogenic Nematodes

• The Western flower thrips, Frankliniella occidentalis is a most economically important pest of many field- and glasshouse-grown vegetables and ornamentals.

• Adults lay eggs in the parenchyma tissue and there are two larval stages (first and second instars), prepupal and pupal stages are present in the life cycle of thrips.

• Adult thrips generally feed by piercing and scraping of the stem, leaf, flower and fruit tissues.

• Both instars also feed on all the aerial plant parts including leaves, flowers and fruits.

• Piercing and scraping of the plant tissues leads to discoloration and drying of the damaged area, in some cases, abortion of flower/leaf buds or distortion of emerging leaves, thus reducing field crop yield and aesthetic value of ornamental plants.

• Thrips are also capable of transmitting tospoviruses such as tomato spotted wilt virus (TSWV) and impatiens necrotic spot virus (INSV) during feeding, thus causing a tremendous loss to agricultural and horticultural greenhouse industries.

• Controlling western flower thrips is difficult because of their small size and cryptic behavior.

• Western flower thrips are commonly eradicated using endosulfan, chlorpyrifos, bendiocarb, and synthetic pyrethrinoids but use of these insecticides is restricted due to their environmental pollution and human health concerns, development of resistance to pesticides and removal of some of the most effective products from the market.

• Biological control agents including predacious mites (Neoseilus cucumeris and Neoseilus degenerans), predacious bugs (Orius insidiosus), entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae) and entomopathogenic nematodes (see below) have been used as alternatives to chemical pesticides.

• The entomopathogenic nematodes species including Heterorhabditis bacteriophora, H. indica, H. marelata and Steinernema abassi, S. carpocapase, and S. feltiae have been found to be effective alternatives to chemical insecticides in controlling western flower thrips.

• The entomopathogenic nematodes specifically attack soil-dwelling second instar larval, prepupal and pupal stages.

• Generally, Heterorhabditis species are more effective than Steinernema species nematodes in controlling western flower thrips.

• The insect- parasitic nematodes such as Thripinema nicklewoodii also have a potential to use as a biological control agent against western flower thrips.

• Application of entomopathgenic nematodes at the rate of 400 infective juveniles/ cm2 of soil surface can cause over 50% mortality of thrip population.

• Nematodes can be easily applied in water suspension as spray applications to the surface of plant growing medium or on the plant foliage infested with western flower thrips.

• Although larval stages, prepupae and pupae are susceptible to entomopathogenic nematodes, H. bacteriophora HK3 strain can cause higher mortality of larval and prepupal stages than pupal stages

How Entomopathogenic Nematodes kill Western Flower Thrips

• When the infective juveniles are applied to the surface of plant growing medium or injected in the potting medium, they start searching for their hosts, in this case Western Flower Thrip larvae, prepupae and pupae.

• Once a larvae, prepupae and pupae has been located, the nematode infective juveniles penetrate into the larvae, prepupae and pupae body cavity via natural openings (mouth, anus and spiracles).

• Infective juveniles of Heterorhabditis also enter through the intersegmental members of the grub/pupa cuticle.

• Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in the larvae, prepupal and pupal blood.

• Multiplying nematode-bacterium complex in the blood causes septicemia and kills the grub usually within 48 h after infection.

• Nematodes feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new larvae, prepupae and pupae in the potting medium/soil.

Biological Control of Black Vine Weevil using Insect Parasitic Nematodes

• Black vine weevil, Otiorhynchus sulcatus is a common insect pest of over 150 plant species that grown in the greenhouses and nurseries.

• Some of the plant species damaged by black vine weevils include Azalea, Cyclamen, Euonymus, Fuxia, Rosa, Rhododendron and Taxus.

• Grubs (Larvae) of these weevils generally girdle the main stem, and feed and damage roots leading to nutrient deficiencies.

• Adults feed on leaves and flowers by notching their edges thus reducing aesthetic value of plants.

• The entomopathogenic nematodes species including Heterorhabditis bacteriophora, H. megidis and Steinernema carpocapase, S. feltiae and S. glaseri have been found to be effective alternatives to chemical insecticides such as chlorpyrifos (Dursban) in controlling black vine weevils.

• Susceptibility of black vine weevil to nematodes is species and strain specific.

• The rate of application of the nematode species/strains that tested against black vine weevil varies (5,000- 60,000 infective juveniles/pot) among different studies but nematodes applied at the rate of 5000- 20,000 infective juveniles/pot can cause up to 100% grub mortality.

• Nematodes can be easily applied in water suspension as spray applications to the surface of plant growing medium but if nematodes are injected at depths deeper than 5 cm i.e. near to grubs they can cause highest mortality of grubs (70-93%) than those nematodes applied to the surface.

• All the four larval stages (instars) and pupae of black vine weevil are susceptible to all entomopathogenic nematode species.

• However, Heterorhabdtis bacteriophora can cause higher mortality of first and second instars than S. carpocapase and S. glaseri.

• Also, all the three nematodes species are equally effective against third and fourth instars of black vine weevil.

How Entomopathogenic Nematodes Kill Black Vine Weevil

• When the infective juveniles are applied to the surface of plant growing medium or injected in the potting medium, they start searching for their hosts, in this case black vine weevil grubs and pupae.

• Once a grub/pupa has been located, the nematode infective juveniles penetrate into the grub or pupa body cavity via natural openings (mouth, anus and spiracles).

• Infective juveniles of Heterorhabditis also enter through the intersegmental members of the grub/pupa cuticle.

• Once in the body cavity, infective juveniles release symbiotic bacteria (Xenorhabdus spp. for Steinernematidae and Photorhabdus spp. for Heterorhabditidae) from their gut in the grub blood.

• Multiplying nematode-bacterium complex in the blood causes septicemia and kills the grub usually within 48 h after infection.

• Nematodes feed on multiplying bacteria, mature into adults, reproduce and then emerge as infective juveniles from the cadaver to seek new grubs or pupae in the potting medium/soil.