Beneficial nematodes

Combating of fall armyworms with beneficial Steinernema carpocapsae nematodes by Ganpati Jagdale

How Steinernema carpocapsae nematodes will kill the fall armyworms?

When Steinernema carpocapsae nematodes are applied to the pasture fields, they will actively search for all the soil-dwelling larval and pupal stages of fall armyworms. After locating larva or pupa, nematodes will enter into their body cavity through the natural openings like anus, mouth and spiracles. In the body cavity, nematodes will release symbiotic bacteria (Xenorhabdus nematophila) in the blood where bacteria will multiply quickly, cause septicemia and kill both larva and pupa within 48 hours of infection. Thus the killing of both larvae and pupae completely stops the emergence of next generation of adult fall armyworms.

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When and how to apply Heterorhabditis indica for small hive beetle control? by Ganpati Jagdale

Small hive beetles, Aethina tumida are the most devastating insect pest of honey bee (Aphis mellifera) hives (Photo 1). Both adults and larvae of small hive beetle cause direct and indirect damages to honeybees. In case of direct damage, larvae of  small hive beetle directly feed on the honeybee brood, honey. pollen and destroy honeycombs. In case of indirect damage, both adults and larvae of small hive beetle spread yeast, Kodamaea ohmeri into the colony and yeast that grows on the honeycombs causes fermentation of honey, which is not suitable for human consumption or as the food for honeybees.

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Kill fall armyworms now and stop their northward migration during spring by Ganpati Jagdale

The fall armyworm, Spodoptera frugiperda is one of the most economically important pests of different plant species including corn, sorghum, forage, and turf grasses.  Although fall armyworm larvae actively damage crops throughout the United States during growing season, they generally die when harsh winter begins in northern, central and eastern United States. Then question arises how they could re-infest fields and cause damage to the crops grown in these areas during spring and summer again.

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Four beneficial nematodes from Portugal by Ganpati Jagdale

Four beneficial nematodes including Heterorhabditis bacteriophoraSteinernema feltiaeSteinernema intermedium and Steinernema kraussei have been reported from Portugal. 

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Two beneficial entomopathogenic nematodes for cucurbit fly control by Ganpati Jagdale

Two beneficial entomopathogenic nematodes including Heterorhabditis bacteriophora (Fig.1) and Steinernema carpocapsae (Fig. 2) have showed a potential to control cucurbit flies, Dacus ciliatus (Kamali et al., 2013). These nematodes are considered as beneficial nematodes because they have been used as biological control agents to control insects that are damaging to crops and harmful to animals

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Two biological agents for the control of strawberry root weevils by Ganpati Jagdale

Strawberry root weevils [Otiorhynchus ovatus] are one of the most important insect pests of strawberry crop.  Adults of strawberry root weevil feed on the edges of strawberry leaves [leaf notching] but this damage is not considered as economically important like the damage caused by their larval stages to strawberry roots [root pruning].

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Control grape root borer, Vitacea polistiformis with beneficial nematodes by Ganpati Jagdale

The grape root borer, Vitacea polistiformis is one of economically important pests of grapes in eastern USA.  Larva stages of this insect feed on grape roots and can cause severe economic damage to the commercial grape industry by killing entire vineyards.  Beneficial nematodes have potential to use as biological control agent to target both larval and pupal stages of root borers.  It has been demonstrated that the beneficial nematodes including Heterorhabditis bacteriophora, H. zealandica and Steinernema carpocapsae can cause over 70% mortality of grape root borer larvae under laboratory conditions (Williams et al., 2002). Read following paper for more information on interaction between beneficial nematodes and grape root borer.

Williams, R.N., Fickle, D.S., Grewal, P.S. and Meyer, J.R. 2002.  Assessing the potential of entomopathogenic nematodes to control the grape root borer, Vitacea polistifirmis (Lepidiptera: Sesiidae) thorough laboratory bioassays. Biocontrol Science and Technology. 12: 35-42. 

Management of small hive beetles with insect-parasitic nematodes by Ganpati Jagdale

Entomopathogenic nematodes including Steinernema riobrave and Heterorhabditis indica were evalusted against a small hive beetle Aethina tumida Murray (Coleoptera: Nitidulidae) in the field. According to Ellis et al. (2010) both nematode species caused over 76% mortality of hive beetles. Shapiro-Ilan et al. (2010) tested efficacy of H. indica and Steinernema carpocapsae against hive beetles and demonstrated that both nematode species when applied through infected host cadavers can cause up to 78% control in hive beetles. This suggests that entomopathogenic nematodes have a potential to use as biological control agents against hive beetles. Read following papers for detail information on effect of entomopathogenic nematodes on the small hive beetles.

Ellis, J.D., Spiewok, S., Delaplane, K.S., Buchholz, S., Neumann, P. and Tedders, W.L. 2010.  Susceptibility of Aethina tumida (Coleoptera: Nitidulidae) larvae and pupae to entomopathogenic nematodes. Journal of Economic Entomology. 103: 1-9.

Shapiro-Ilan, D.I., Morales-Ramos, J.A., Rojas, M.G. and Tedders, W.L. 2010.  Effects of a novel entomopathogenic nematode-infected host formulation on cadaver integrity, nematode yield, and suppression of Diaprepes abbreviatus and Aethina tumida. Journal of Invertebrate Pathology. 103: 103-108.

Use Beneficial nematodes to control leaf beetles by Ganpati Jagdale

  • 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.
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Use Beneficial nematodes to control Black vine weevil Otiorhynchus spp by Ganpati Jagdale

  • 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.
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Life cycle of entomopathogenic nematodes (EPNs) by Ganpati Jagdale

 

Entomopathogenic nematode life cycle

  • EPNs complete most of their life cycle in insects with an exception of infective juveniles, the only free-living stage found in soil.
  • Infective juveniles of both Steinernema and Heterorhabditis locate a host and enter through its natural body openings such as mouth, anus or spiracles.
  • Infective juveniles of Heterorhabditis also enter through the intersegmental members of the host cuticle.
  • Infective juveniles then actively penetrate through the midgut wall or tracheae into the insect body cavity (hemocoel) containing insect blood (haemolymph).
  • Once in the body cavity, infective juvenile releases symbiotic bacteria from its intestine in the insect haemolymph.
  • Bacteria start multiplying in the nutrient-rich haemolymph and infective juveniles recover from their arrested state (dauer stage) and start feeding on multiplying bacteria and disintegrated host tissues.
  • Toxins produced by the developing nematodes and multiplying bacteria in the body cavity kill the insect host usually within 48 hours.
  • These bacteria also produce a plethora of metabolites, toxins and antibiotics with bactericidal, fungicidal and nematicidal properties, which ensures monoxenic conditions for nematode development and reproduction in insect cadaver.
  • Heterorhabditid and Steinernematid nematodes differ in their mode of reproduction. For example, in heterorhabditid nematodes, the first generation individuals are produced by self-fertile hermaphrodites (hermaphroditic) but subsequent generation individuals are produced by cross fertilization involving males and females (amphimictic). In Steinernematid nematodes with an exception of one species, all generations are produced by cross fertilization involving males and females (amphimictic).
  • Depending on availability of food resource, both heterorhabditid and steinernematid nematodes generally complete 2-3 generations within insect cadaver and emerge as infective juveniles to seek new hosts.
  • Generally, life cycle of entomopathogenic nematodes (from infective juvenile penetration to infective juvenile emergence) is completed within 12- 15 days at room temperature. The optimum temperature for growth and reproduction of nematodes is between 25 and 300C.

Insect parasitic nematodes are our friends by Ganpati Jagdale

Nematodes are defined as thread-like microscopic, colorless, unsegmented round worms found in almost all habitats especially in soil and water. Nematodes may be free-living, predacious and parasitic. Nematodes that are considered our friends include entomopathogenic nematodes, insect-parasitic nematodes, slug-parasitic and free-living nematodes.

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