Influence of potting media on the virulence of entomopathogenic nematodes against black vine weevil, Otiorhynchus sulcatus

It has been demonstrated that five different types of commercial potting media including peat, bark, coir, and peat blended with 10% and 20% compost green waste can influence the virulence of entomopathogenic nematodes against third-instar black vine weevil, Otiorhynchus sulcatus.  For example, Heterorhabditis species including Heterorhabditis bacteriophora UWS1 strain, H. megidis, H. downesi can cause 100% mortality of black vine weevil grubs in all the five types of media but  Steinernema species including Steinernema feltiae, S. carpocapsae, and S. kraussei can cause 100% black vine weevil grub mortality only in the peat blended with 20% compost green waste.  These results suggest that when growers are selecting entomopathogenic nematodes to control black vine weevil, Otiorhynchus sulcatus in their nurseries/greenhouses, they should take into consideration the type of potting media used in growing their plants. Please read following paper for the information on the method of nematode application rates and timings.

Ansari, M. A. and Butt, T. M. 2011.  Effect of potting media on the efficacy and dispersal of entomopathogenic nematodes for the control of black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae). Biological Control 58: 310-318.

Ansari, M.A., Shah, F.A. and Butt, T.M. 2010.  The entomopathogenic nematodeSteinernema kraussei and Metarhizium anisopliae work synergistically in controlling overwintering larvae of the black vine weevil, Otiorhynchus sulcatus, in strawberry growbags. Biocontrol Science and Technology. 20: 99-105.

Control of the black vine weevil Otiorhynchus sulcatus infesting strawberry fields

It has been reported that entompathogenic nematodes including Heterorhabditis megidis and Steinernema kraussei are effective against the black vine weevil Otiorhynchus sulcatus infesting strawberry fields (Haukeland and Lola-Luz, 2010).  It has been suggested that the soil type and soil temperature plays a significant role in efficacy of these nematodes against the black vine weevil.  It is also noted that H. megidis performs better at soil temperatures above 10oC and S. kraussei at below 10oC. References:

Haukeland, S. and Lola-Luz, T. 2010.  Efficacy of the entomopathogenic nematodes Steinernema kraussei and Heterorhabditis megidis against the black vine weevil Otiorhynchus sulcatus in open field-grown strawberry plants. Agricultural and Forest Entomology.12363-369

Biological control of filbertworm, Cydia latiferreana with entomopathogenic nematodes

Filbertworm, Cydia latiferreana is considered as an economically important insect pest of hazelnuts, Corylus avellana in North America.  Three entomopathogenic nematode species including Heterorhabditis marelatus Pt. Reyes strain, Steinernema carpocapsae All strain and Steinernema kraussei L137 strain have been tested as biological control agents against filbertworm under both laboratory and field condition (Chambers et al., 2010; Bruck and Walton, 2007). These studies showed that these nematodes can cause about 73–100% mortality of filbertworms (Bruck and Walton, 2007) and can be used to manage overwintering worms on the hazelnut orchard floor (Chambers et al., 2010).

Read following literature for information on the interaction between entomopathogenic nematodes and filbertworm.

Bruck, D.J. and Walton, V.M. 2007.  Susceptibility of the filbertworm (Cydia latiferreana, Lepidoptera:Tortricidae) and filbert weevil (Curculio occidentalis, Coleoptera: Curculionidae) to entomopathogenic nematodes. Journal of Invertebrate Pathology. 96: 93–96.

Chambers, U. Bruck, D.J., Olsen, J. and Walton, V.M. 2010.  Control of overwintering filbertworm (Lepidoptera: Tortricidae) larvae with Steinernema carpocapsae. Journal of Economic Entomology. 103: 416-422.

How entomopathogenic nematodes find their insect hosts (Foraging Strategies)

Infective juveniles of entomopathogenic nematodes use three different strategies to find their insect hosts.1. Ambush foraging: Ambushers such as Steinernema carpocapsae and S. scapterisci have adapted "sit and wait" strategy to attack highly mobile insects (billbugs, sod webworms, cutworms, mole-crickets and armyworms) when they come in contact at the surface of the soil.  These nematodes do not respond to host released cues but infective juveniles of some Steinernema spp can stand on their tails (nictate) and easily infect passing insect hosts by jumping on them.  Since highly mobile insects live in the upper soil or thatch layer, ambushers are generally effective in infecting more insects on the surface than deep in the soil. 2. Cruise foraging: Cruiser nematodes such as Heterorhabditis bacteriophora, H. megidis, Steinernema glaseri and S. kraussei generally move actively in search of hosts and therefore, they are distributed throughout the soil profile and more effective against less mobile hosts such as white grubs and black vine weevils.  Cruisers never nictate but respond to carbon dioxide released by insects as cues. 3. Intermediate foraging: Some nematode species such as Steinernema feltiae and S.riobrave have adapted a strategy in between ambush and cruise strategies called an intermediate strategy to attack both the mobile and sedentary/less mobile insects at the surface or deep in the soil.  Steinernema feltiae is highly effective against fungus gnats and mushroom flies whereas S.riobrave is effective against corn earworms, citrus root weevils and mole crickets.