Heterorhabditidae nematodes as a biological control for the small hive beetle.

[ednaknightlora]

I ordered 5 million beneficial nematodes (genera Heterorhabditidae) to inoculate the soil around some bee hives. These insect attacking nematodes inject a mutualistic bacteria into the small hive beetle larvae. The insides turn to mush. The juvenile nematodes eat the mush and bacteria and mature. The mature nematodes lay eggs inside the dead larvae which hatch into juveniles. 

I had a look at them under the microscope and couldn't really see a mouth so I did a bit of research. As it turns out, they are nonfeeders at the specialized third juvenile. My question is - what kind of nematode are they as adults and if we can't see a clear mouth looking at soil samples, do we assume the critters are nonfeeding juveniles? Do they turn into bacteria feeding nematodes? Before applying the nematodes I applied some biologically active compost and the day of application of the nematodes, I made a compost extract. Is it worth it if the critters are nonfeeders? My thinking is that creating a healthy diverse soil food web with help keep predators and prey all happy and hanging around.

Thanks a bunch. I am having a blast. 

Edna

[Ingham, Elaine]

Heterorhabditus is strictly a bacterial-feeding nematode.

They sell the non-feeder larval stage, because that means they don't need to add food into the material they are selling. As soon as the third larval stage nematodes find food though, once you add them to the soil, they moult into the fourth larval stage, preparatory to becoming adults.

The adults go looking for soft-bodied insect pests in soil, which means the larval stages of the beetles are just what they like, and the bites the nematode takes inoculates the bacterium that Heterorhabditus carries with it. That bacterium starts to grow and chews its way through the exoskeleton of the insect's body, and then the bacterium grows rapidly in the insect body. The adult nematode then feasts on the bacteria, lays eggs, and the baby nematodes hatch in an environment that abounds with the bacterium they need, and off the baby nematodes go looking for more insect pests.



Elaine R. Ingham
Chief Scientist
Rodale Institute

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[ednaknightlora]

Thank you so much for your reply. I will be getting some delivered and plan to observe their lifecycle. 

Edna