Journal of Economic Entomology (1997) 90, 326-332

J. Daniel Hare and Joseph G. Morse (1997)
Toxicity, persistance, and potency of sabadilla alkaloid formulations to citrus thrips (Thysanoptera: Thripidae)
Journal of Economic Entomology 90 (2), 326-332
Abstract: Toxicity of the major alkaloids present in commercial formulations of sabadilla, Veratran D, was determined in laboratory bioassays with adult female citrus thrips, Scirtothrips citri (Moulton). Both cevadine and veratridine, the 2 major components of the insecticidal fraction of sabadilla, were highly toxic to citrus thrips. LC₅₀s of cevadine and veratridine were 1825 and 29.91 ng/cm², respectively, whereas veracevine, the parent alkanolamine, was much less toxic (LC₅₀ of 17,314 ng/cm²). A field trial with Veratran D showed that alkaloid levels on leaves declined to 60% of the initial deposit within 20 h of application and to undetectable levels within 7d. Analyses of stored commercial samples of Veratran D from each year 1990-1994 indicated that levels of each of the 2 major alkaloids, as well as the "total" alkaloid content determined gravimetricallywere similar. In contrast, >3-fold variation in the level of veratridine was noted in 4 samples of Veratran D taken in 1995 despite similar levels of total alkaloids among samples. Future formulations of Veratran D might be improved by standardizing the levels of cevadine and veratridine rather than the level of total alkaloids.
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Database assignments for author(s): J. Daniel Hare

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Scirtothrips citri