SpK is a bio-insecticide based on the bacterium Yersinia entomophaga.  The whole organism, toxic metabolites and identified genes all display insecticidal properties when injested by susceptible insect pests. The level of this insecticidal activity compares favourably with commercial bio-rational products.

SpK:

• Is at least as efficacious as Bt, but against a broader spectrum of insect pests,
• Will be commercially competitive with Bt
• May be more persistent on insect food surfaces after application
• Being yet undeveloped, has substantial potential for future optimisation in a development process
• At least as the whole organism, qualifies as a suitable component of ‘organic’ insect control regimes.
• Has no detected mammalian or environmental toxicity concerns that might prejudice product registrations
• Is not difficult, complicated or expensive to produce by fermentation and may be formulated into dry preparations for packaging, storage and distribution under reasonable ambient conditions. These dry formulations are conveniently dispersed in water for spray or similar application onto surfaces of pest insect food.
   

In addition:

SpK is currently being tested for insecticidal activity on diamond back moth larvae that are resistant to Bt, spinosad or a pyrethroid insecticide. It is expected that SpK will display no cross-resistance to any of these insecticide groups. Therefore SpK can be expected to a valuable tool in resistance prevention or management programmes that involve these insecticides. SPK may complement, replace or compete with other insecticides depending on biological and commercial considerations.

Figure  The growth of Y. entomophaga in standard LB brothat (Δ) 25oC; (¦) 30oC and (?) 37oC over a duration of seventy two hours

 

Results of growth curve analysis at 25^oC, 30^oC and 37^oC in standard LB broth were undertaken over a 72 hour period (refer figure). Initially cell counts over the first few hours were highest when grown at 37^oC. However a drop in the mean cell count was noted at all temperatures between 8 and 15 hours. This was followed by a period of rapid growth from 14 hours onward and growth at 25^oC and 30^oC surpassed that at 37^oC. The highest mean cell count beyond 20 hours was achieved at 25^oC (1.30 x 10¹⁰ cfu/ml). The optimal growth of Y. entomophaga was defined as 25^oC.