How’s Your Entomolgy - BT vs. Certain Lepidoptera

[Firstflush]

So there are a few species of caterpillar in Lepidoptera that are resistant to BT. Being growers of all sorts of things, we (I) try to choose BT because it is considered safe on our native bees and euro honeybees. I’m not the hippy type but try to use sound horticultural practices. I want as many pollinators around as possible.

I am aware that a certain type of bud worm mainly associated with geraniums and the rose slug are considered resistant to BT.

Are you all aware of any other caterpillars that are resistant to BT?

 

[Woocash]

British Telecom?

 

[Potawatomi13]

What is BT?

 

[Bnana]

Resistance against BT (a insecticide based on Bacillus thuringiensis) is quite rare and mostly in species that feed on crops. Caterpillar that feed on trees are unlikely to be resistant.
BT is not harmless but much less harmful than many other insecticides such as neonics (often promoted here but banned in the EU).

Rose slug is not a caterpillar but a saw fly larva and therefore not sensitive to the BT used against caterpilars.

 

[Firstflush]

Resistance against BT (a insecticide based on Bacillus thuringiensis) is quite rare and mostly in species that feed on crops. Caterpillar that feed on trees are unlikely to be resistant.
BT is not harmless but much less harmful than many other insecticides such as neonics (often promoted here but banned in the EU).

Rose slug is not a caterpillar but a saw fly larva and therefore not sensitive to the BT used against caterpilars.

Good stuff. I understand the geranium budworm to be the actual tobacco budworm.

Additionally, the whole resistance to BT thing may be a crock as the budworms head is typically feeding with its head buried in the flower material. BT application is applied to the surface of a plant. How would one get the BT into the caterpillars mouth if it’s head is buried for most of its lifecycle? So there is that…

 

[TN_Jim]

Indianmeal moth & Diamondback (or Cabbage) moth are resistant

Problems of insect resistance to Bacillus thuringiensis

Insect resistance to Bacillus thuringiensis (Bt) has been a recognised problem for only about 6 years. It now seriously threatens both conventional an…

www.sciencedirect.com

 

[Bnana]

Indianmeal moth & Diamondback (or Cabbage) moth are resistant

Problems of insect resistance to Bacillus thuringiensis

Insect resistance to Bacillus thuringiensis (Bt) has been a recognised problem for only about 6 years. It now seriously threatens both conventional an…

www.sciencedirect.com

Both are pretty unlikely to be a problem for bonsai, unless you have a broccoli forest .

 

[Firstflush]

I didn’t know the cabbage looper was resistant, good info for when the veggies get hammered.
Spinosad will do it, however, it is really hard on bees.

 

[Leo in N E Illinois]

Put a call into your local county ag extension agent. They should know what is resistant locally. Every county in the USA has an Ag. Extension Agent who is versed in their county's IPM issues and resistance issues. Your taxes pay for them, use their expertise.