Spear-Lep is a biological insecticide that is part of the first peptide-based insecticides that offer a new mode of action (IRAC 32). Spear-Lep is registered for use in Wisconsin on several fruit crops including small fruits and berries (Group 10) such as blackberry, blueberry, cranberry, currant, grape, raspberry, and strawberry; pome fruit (Group 11) such as apple, pear, and quince; and stone fruit (Group 12) such as apricot, cherry, nectarine, peach and plum. Spear Lep is marketed by Vestaron Corporation under a liquid formulation with 0.17 lbs of active ingredient per gallon.
Mode of action and effect. The active ingredient in Spear-Lep is the biological peptide GS-Omega/Kappa-Hxtx-HV1a and constitutes an entirely new class of insecticides of the IRAC group 32. The mode of action for this peptide is by modulating the nicotinic acetylcholine receptor site II (differing from Spinosyns that modulate site I of these receptors and are in IRAC group 5). The peptide works only in combination with a low dose of the bacteria Bacillus thuringiensis kurstaki (Btk) which is highly specific to Lepidopteran pests (moths and butterflies). As the insect feeds on treated surfaces, the Btk crystals rupture the gut cells allowing the peptide to access the nervous system where it helps bind the neurotransmitter acetylcholine to the acetylcholine receptors, causing persistent depolarization of the neuron, leading to the hyperexcitation of the neuron, and resulting in paralysis and death. Spear-Lep (+Btk) is an insecticide with foliar activity that is fast acting by ingestion of treated plant surfaces. Affected insects will rapidly stop feeding, become paralyzed, and eventually die.
Spear-Lep in combination with Btk targets primarily Lepidopteran moth insects as the Btk offers high specificity to Lepidopterans. Of interest to cranberry on the label are fruitworms, spanworms, loopers, and cutworms. Although black-headed fireworm is not specifically mentioned as a target pest on the label, in Wisconsin, you are allowed to use products on pests not present on the label, as long as the product is labeled for the crop you are applying it to. In our trials, Spear-Lep + Btk was very effective at controlling sparganothis fruitworm and cranberry fruitworm, as well as black-headed fireworm and spanworms, using 3-4 applications per season. For more information on our results, refer to this factsheet from Vestaron.
Application restrictions. Spear-Lep may be applied by ground equipment, chemigation, and air, and specific recommendations are provided for the different application methods regarding direction for use, spray volumes, and spray drift requirements. For more information on mixing and spraying, and all other considerations, please see the product label. For optimal performance, it is recommended to use a non-ionic spreader/sticker surfactant at 0.125% v/v.
Environmental impacts. Spear-Lep is considered to have very low to no risk to bees, fish, and mammals. Do not apply Spear-Lep directly to water or to areas where surface water is present.
Considerations. Please check with your handlers before using a new product as handlers may have restrictions on certain products for domestic and/or foreign markets. Handlers may extend PHIs beyond the number of days stated on the label to reduce residues, so please always check with your handlers. And as always, make sure to read the labels before using any pesticide.
Resources. You can find the label for Spear-Lep at the following link:
Happy growing season!This article was posted in Cranberry, Insects and tagged biological insecticide, Christelle Guédot, Cranberries, insect, insect control, Insecticides, insects.