Encoate | SpK

SpK

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.

Porina (Wiseana spp) is an endemic intractable pest of pasture in NZ. The caterpillars are soil inhabiting and by night emerge to the soil surface and graze near their burrows. In affected areas the effects of this grazing on pasture production can be very severe.

A study was conducted to compare the effect of Y. entomophaga vs. Dipel.(Bt) on protecting white clover from Porina.

Ten containers of white clover each were treated with:

• 1% Y. entomophaga biopolymer gel diluted 1:1 with water and sprayed on plants until runoff (approx 35 ml/container),

• Y. entomophaga on kibbled wheat bait was applied at 50 kg/ha (0.7 g/container) but with two grains placed within 20 mm of each plant and the remainder sprinkled as evenly as possible throughout the container,

• Bacillus thuringensis kurstaki (Dipel) in a 1% solution (with Triton X as a surfactant at the recommended rate 0.2ml/l) sprayed to runoff (approx 35 ml/container)

• Not treated (control).

clover and larvae

Figure: An experimental container showing nine white clover plants and seventeen larvae containers positioned for larval establishment prior to treatment.

Figure . White clover plants scored for feeding damage.

Table . Damage to white clover plants 4 and 11 days after treatment. Number of plants (out of 9) (SEM) in each damage category.

	18 June				25 June
	100%	+50%	-50%	0%	100%	+50%	-50%	0%
Control	1.5 (0.3)	2.3 (0.4)	4.5 (0.4)	0.7 (0.5)	4.3 (0.3)	2.2 (0.30	2.5 (0.3)	0 (0)
Y. entomophaga Gel	0.4 (0.2)	1.8 (0.4)	5.6 (0.7)	1.2 (0.8)	0.5 (0.3)	2 (0.3)	6.5 (0.4)	0 (0)
Y. entomophaga Baits	0.8 (0.3)	1.1 (0.4)	5.3 (0.4)	1.7 (0.5)	1.2 (0.3)	1.7 (0.3)	6.1 (0.5)	0 (0)
Dipel	1.9 (0.3)	1.8 (0.2)	4.6 (0.4)	0.7 (0.4)	4.6 (0.7)	2.4 (0.4)	2.2 (0.6)	0 (0)

Table :Wiseana spp larvae survival and white clover production

	Surviving larvae/18		White clover production g DM
	mean	SEM	mean	SEM
Control	15.8	0.63	0.26	0.05
Y. entomophaga Gel	4.6	0.62	0.87	0.10
Y. entomophaga Baits	5.6	0.48	0.65	0.06
Dipel	12.2	0.92	0.31	.07

In summary both formulations of Y. entomophaga were associated with mortality of Wiseana spp larvae and afforded the white clover plants some protection from larval feeding.

In both instances Y. entomophaga was statistically superior to Dipel.