Fate of spinosad in litter and soils of a white spruce plantation in central Ontario

Abstract

Spinosad is a natural insecticide with potential as a novel biorational control agent for spruce budworm (Choristoneura fumiferana [Clem]), the most destructive insect defoliator of spruce and balsam fir in Canada. Concurrent terrestrial fate experiments were conducted under full coniferous canopy and in a natural opening of a mature white spruce (Piecea glauca [Moench]) plantation of central Ontario to examine the fate and persistence of spinosad in the forest floor and underlying soils. Mean initial residues of spinosyn A and D were approximately 0.2 and 0.02 microgram g-1, respectively, in thatch and exposed soils, but were substantially higher, 2.72 and 0.36 micrograms g-1, in litter under coniferous canopy. Results demonstrated that spinosad residues in spruce litter, graminaceous thatch and exposed sandy loam soils dissipated rapidly, following hyperbolic or exponential decline models. Dissipation time (DT50) values ranged from 2.0 to 7.8 days, depending on matrix and experimental conditions. Transient increases in demethylated metabolite residues confirmed that the parent product was degraded in situ. No evidence of vertical mobility of any of the analytes was observed.

The Side-Effect of Organic Insecticide Spinosad on Biochemical and Microbiological Properties of Clay Soil

“…Very short half-lives values (<1 day) for spinosad was observed in agricultural soils of the southern USA [Hale and Portwood, 1996]. Thompson et al [2002], found that spinosad is quickly metabolized by soil microorganisms under aerobic condition, however, under anaerobic conditions, the degradation is slower. The results obtained by Gębala and Mickiewicz [2012] shown that spinosad is not ready biodegradable in water and not toxic to microbial inoculum.…”

“…Although such compounds tend to be water soluble, easily metabolized and non-bioaccumulatory, biogenic sourcing does not necessarily confer environmental acceptability [Thompson et al, 2000]. Therefore, assessment of environmental persistence, fate and toxicological properties, including stud-ies, is necessary for these compounds [Thompson et al, 2002].…”

“…It shows minimal acute toxicity (LD 50 (rats)>5000 mg·kg -1 ), is non-carcinogenic, non-mutagenic and non-neurotoxic in mammalian test animals [Thompson et al, 2002] and also has a favourable environmental profile as it does not leach, bioaccumulate, volatilize or persist in the environment [Sharma et al, 2007]. Laboratory and field studies demonstrate that spinosad may undergo different abiotic and biotic degradation in soils [Thompson et al, 2002].…”

The spinosyn family of insecticides: realizing the potential of natural products research

“…127,128 Spinosyns also did not show a lengthy persistence in soil and litter, presumably in large part due to facile degradation by soil organisms. [128][129][130][131] Spinosyns have also been found to undergo facile metabolism in several mammals and fowl. 18,132 Overall, the spinosyns are readily subject to a number of diverse degradative pathways and metabolic mechanisms that reduce their persistence in plants, animals and the environment.…”

Dissipation and Residues of Spinosad in Eggplant and Soil

“…Previous studies on the environmental fate of spinosad focused on the degradation of spinosad in aqueous systems (Cleveland et al, 2002a;Liu et al, 2005), and assessment of the ecological risk of spinosad application on cotton and white spruce (Thompson et al, 2002a(Thompson et al, , 2002bCleveland et al, 2002b). The purpose of the present work was to study the dissipation rate and ultimate residue of spinosad in an eggplant field ecosystem, and thereby provide an evaluation for scientific, safe use of spinosad.…”