Some insecticide ingredients such as abamectin and spinosad are produced by micro-organisms. The microbes are cultured (grown in a prepared medium) and exude the active ingredients, which are then isolated for formulation as insecticide active ingredients. Parasitic nematodes are also cultured. However, as multicellular organisms, they are not regulated as insecticides by the Environmental Protection Agency (EPA) and are considered biological control agents.
Abamectin baits, such as PT® 370 Ascend™ Fire Ant Stopper Bait and others (Varsity, Clench, Advance Carpenter Ant Bait, Avid Insecticide/Miticide) affect fire ants and related ants. Abamectin is a natural fermentation product produced by a soil microorganism, Streptomycetes avermitilis, an actinomycete.1 Because the product is natural in origin, it may fit into some “organic” production programs.
1Campbell, W. C. 1989. Ivermectin and Abamectin. Springer-Verlag. New York. 363 pages.
Spinosad is a relatively new group of active ingredients found within insecticide products, composed of two active derivatives, spinosyns A and D. These spinosyns are products from the fermentation of the soil actinomycete, Saccharopolyspora spinosa. Spinosad disrupts the insect’s nerve impulse transmission causing rapid excitation, paralysis and death. It is a fast-acting insecticide and is effective at low concentrations. It is low in toxicity to mammals with moderate toxicity to some fish and aquatic organisms. Since spinosad is derived from a naturally occurring bacterium, it fits into the organic methods for controlling insects, including the red imported fire ant, Solenopsis invicta Buren (Hymenoptera:Formicidae).
Spinosad bait for imported fire ants was registered by the Environmental Protection Agency (EPA) in 2000 (Drees and Gold 2003). Justice® fire ant bait (0.015% spinosad, Dow AgroSciences LLC) was registered for use on cattle pastures until it was removed from the market. However, its use was only for individual mound treatment (at a rate of 4 T per mound). A number of products were marketed in the years following, including the products Penn-Kill™ Fire Ant Killer, Eliminator® Fire Ant Killer Bait, Ortho® Fire Ant Killer Bait, Maxide®, Strike® Fire Ant Killer Bait, Fertilome® Come & Get It Fire Ant Killer with instructions for use as both broadcast (at a rate of 4 to 6 lbs. per acre) and mound treatments.
Following certification by the Organic Materials Review Institute (OMRI), the product became part on an “organic” two-step method for imported fire ant control (Drees 2002, Fire Ant Update 1(4) (Product Updates).
In 2003, Green Light® Fire Ant Control with Conserve® was issued with specific instructions for use in home gardens of 1 acre or less. Currently (2005), SWCP Conserve® Professional Fire Ant Bait (Southwest Contract Packaging and Green Light®) is registered for use to control or suppress imported fire ants in:
- Lawns and other turf areas, including sod farms
- Recreation areas, including golf courses, playgrounds and playing fields
- Non-crop areas such as roadsides, rights of way, industrial areas, campgrounds, parks, recreational areas, rough turf areas, farmsteads, corrals and around animal housing facilities
- Ornamentals in landscapes and nurseries
- Rangeland and permanent pastures (individual mound treatment, only)
- Most crops, including, but not limited to tree nuts, citrus, stone fruit, tropical tree fruit, soybeans, and vegetables
Note: Dow no longer produces Conserve Professional Ant Killer (per Dow Sept. 15, 2008).
Unfortunately, inconsistent results of individual mound and broadcast treatment (see Engler et al. 2005, Drees and Summerlin 2005) have been reported from field evaluations and other applied research and result demonstration reports posted on the Imported Fire Ant Research and Management Project Web site (search for spinosad), particularly with spring and early summer broadcast applications (Barr 2002).
The use of spinosad as a mound drench treatment formulation could make use of this insecticide ingredient more consistently effective and provide an alternative to the bait formulation, with previous site uses for the bait products allowing the drench to be used in livestock pastures as an alternative to carbaryl (Sevin® agricultural formulations).
Interest in organic and alternative methods of fire ant control persists (Drees and Lennon 1998). Organic Solutions Fire Ant Killer, containing 0.1% pyrethrins plus 1% piperonyl butoxide (PBO) and 85% diatomaceous earth (DE) is not considered organic due to the synthetic ingredient PBO. Numerous studies have assessed alternative ingredients for expensive and erratically available pyrethrins for certifiably organic active ingredient or a natural pyrethrins synergist to replace the PBO component. Spinosad was evaluated in this trial as a replacement ingredient.
Trials have been conducted to evaluate the effectiveness of spinosad as a contact insecticide applied as a mound drench compared to the effectiveness as a bait formulation for the control of the red imported fire ant (see Urban IPM Report pages 23-34). Several formulations of spinosad were assessed as a mound drench treatment, including Entrust® Naturalyte Insect Control (80% spinosad, Dow AgroSciences LLC, 9330 Zionsville Rd., Indianapolis, IN 46268), and 0, 2, 5 and 10% concentrations of Entrust® mixed in diatomaceous earth formulated and supplied by Organic Solutions. The bait formulation tested was Green Light with Conserve® (0.015% spinosad) on conventional fire ant bait formulation in which spinosad is dissolved in soybean oil and requires ingestion by the ants. The untreated control treatment included a “water check” receiving water drench only.
Source for Fermentation Products: Drees, B. M., and R. E. Gold. 2003. Development of integrated pest management programs for the red imported fire ant (Hymenoptera: Formicidae). J. Entomol. Sci. 38(2):170-180.