J. Th. Arnason

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Accessions representing twenty eight landraces of maize were assessed for susceptibility to the maize weevil, Sitophilus zeamais in standardized resistance tests. Susceptibility parameters such as weight loss of grain, number of insect progeny produced, the Dobie index of susceptibility, and oviposition on grain were found to vary significantly by genotype,(More)
2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), the major hydroxamic acid present in corn, and its tritiated derivative, were prepared synthetically for use in the determination of the toxicokinetics of this insect deterrent in the European corn borer (ECB),Ostrinia nubilalis. In growth studies with DIMBOA (0, 0.05, 0.2, and 0.5 mg/g diet), the mean(More)
Essential oils from sweet basil, Ocimum basilicum, and African basil, O. gratissimum, (Labiatae) grown in Guinea were obtained by steam distillation. Following exposure of newly emerged adult beetles (Callosobruchus maculatus) to 12h of fumigation using pure essential oils at a dose of 25&mgr;l/vial, 80% mortality was recorded for O. basilicum, 70% for O.(More)
Total above ground plant biomass in a 45 year old seasonally dry tropical hardwood forest was estimated to be approximately 56,000 kg/ha oven dry weight. Nutrients immobilized in the standing vegetation were: N, 203 kg/ha; P, 24 kg/ha; K, 234 kg/ha; Ca, 195 kg/ha; Mg, 47 kg/ha; Na, 9 kg/ha; Mn, 1 kg/ha; Cu, 0.5 kg/ha; Zn, 3 kg/ha; Fe, 4 kg/ha. Total(More)
Economically important trees such as ramón have been shown to have a high density in the civic-ceremonial core zone of ancient Maya ruins. The distribution of such trees is probably the result of their requirements for growth and reproduction, which are optimal on the ruins, and not because they are the descendants of trees planted by the Maya aristocracy.
Plant lifeform composition and levels of nutrients accumulated by fallows aged 1, 2 and 3 years under shifting (milpa) cultivation in Belize were measured. Levels of N, P and K allocated to leaves rapidly reached a plateau in 1 year old fallows with little increase in 2 and 3 year old sites. In stem material, K was accumulated rapidly, with little increase(More)
Insecticidal and growth-reducing properties of extracts of 14 species of American neotropical Piperaceae were investigated by inclusion in diets of a polyphagous lepidopteran, the European corn borer,Ostrinia nubilalis. Nutritional indices suggested most extracts acted by postdigestive toxicity.Piper aduncum, P. tuberculatum, andP. decurrens were among the(More)
The purpose of this study was to develop an LC/MS assay to accuratelydetect three mycotoxins produced by Fusarium graminearum in various matrices. Using different LC conditions, deoxynivalenol (DON), 15-acetyldeoxynivalenol (15-ADON), and zearalenone (ZEN) were detected in four different matrices (fungalliquid cultures, maize grain, insect larvae and pig(More)
Photo-activated plant secondary compounds have been shown to be toxic to many organisms including insects. Insect defenses include behavioral mechanisms such as light avoidance, as well as specific biochemical defenses such as antioxidants and antioxidant enzymes. These antioxidant defenses eliminate or quench the deleterious singlet oxygen and free(More)
The maize-derived secondary chemical 6-methyoxybenzoxazoii-none (MBOA) and a tritiated derivative were prepared synthetically for a detailed examination of their toxicity and toxicokinetics in the European corn borer (ECB),Ostrinia nubilalis. During feeding trials with MBOA incorporated into meridic diets (at 0, 0.5, 1.5, 2.5, and 4.0 mg/g diet), the mean(More)