Journal of Economic Entomology (2003) 96, 798-804

Dionne Clarke-Harris and Shelby J. Fleischer (2003)
Sequential sampling and biorational chemistries for management of lepidopteran pests of vegetable amaranth in the Caribbean
Journal of Economic Entomology 96 (3), 798-804
Abstract: Although vegetable amaranth, Amaranthus viridis L. and A. dubius Mart. ex Thell., production and economic importance is increasing in diversified peri-urban farms in Jamaica, lepidopteran herbivory is common even during weekly pyrethroid applications. We developed and validated a sampling plan, and investigated insecticides with new modes of action, for a complex of five species (Pyralidae: Spoladea recurvalis (F.), Herpetogramma bipunctalis (F.), Noctuidae: Spodoptera exigua (Hubner), S. frugiperda (J. E. Smith), and S. eridania Stoll). Significant within-plant variation occurred with H. bipunctalis, and a six-leaf sample unit including leaves from the inner and outer whorl was selected to sample all species. Larval counts best fit a negative binomial distribution. We developed a sequential sampling plan using a threshold of one larva per sample unit and the fitted distribution with a k_c of 0.645. When compared with a fixed plan of 25 plants, sequential sampling recommended the same management decision on 87.5%, additional samples on 9.4%, and gave inaccurate recommendations on 3.1% of 32 farms, while reducing sample size by 46%. Insecticide frequency was reduced 33-60% when management decisions were based on sampled data compared with grower-standards, with no effect on crop damage. Damage remained high or variable (10-46%) with pyrethroid applications. Lepidopteran control was dramatically improved with ecdysone agonists (tebufenozide) or microbial metabolites (spinosyns and emamectin benzoate). This work facilitates resistance management efforts concurrent with the introduction of newer modes of action for lepidopteran control in leafy vegetable production in the Caribbean.
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Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera exigua	Amaranthus (crop)	Jamaica
	Spodoptera frugiperda	Amaranthus (crop)	Jamaica
	Spodoptera eridania	Amaranthus (crop)	Jamaica
	Spoladea recurvalis	Amaranthus (crop)	Jamaica
	Herpetogramma bipunctalis	Amaranthus (crop)	Jamaica