Density-Dependent Reproductive Success In Tribolium Castaneum (Herbst) (Coleoptera : Tenebrionidae)

in Journal of Stored Products Research (2008), 44(3), 285-289

Two strains of Tribolium castaneum, one being susceptible to malathion (Asm) and the other malathion-specific resistant (PRm), were used to assess the effect of population density and its interaction with ... [more ▼]

Two strains of Tribolium castaneum, one being susceptible to malathion (Asm) and the other malathion-specific resistant (PRm), were used to assess the effect of population density and its interaction with genetic background in reproductive success. A highly significant allometric relationship between female body weight and fecundity (R2=0.413) and another between female body weight and larval survivorship (R2=0.561) were found. Data showed that population density exerted an indirect effect on the reproductive success. The body weight of the Asm female was not affected by variations in population density but the body weight of the PRm female increased with reduced population density. The genetic background (strain) and/or malathion-specific resistance greatly influenced reproductive success. Concerning the percentage survivorship of offspring of the two strains, there was an opposite trend with increased population density: in PRm, survivorship was lower at high density (76.64±13.75; mean±SD) and higher at low density (88.39±7.61), whereas in Asm, survivorship was higher at high density (53.39±15.57) and lower at low density (43.99±20.08). The PRm female laid more eggs than the Asm. Reproductive success was significantly higher in PRm than in Asm. In addition, the genetic background (the strain) and/or the pleiotropic effect of malathion-specific resistance had a significant effect on the fecundity of PRm because the differences in fecundity and reproductive success between Asm and PRm went beyond the body weight of the female and might be explained by their genetic background and/or the pleiotropic effect of malathion-specific resistance. [less ▲]

Efficacy of diatomaceous earth formulations admixed with grain against populations of Tribolium castaneum

in Journal of Stored Products Research (2005), 41(2), 121-130

The efficacy of diatomaceous earth (DE) to control stored-products Coleoptera on stored grain was examined against several populations of the red flour beetle, Tribolium castaneum (Herbst). Four ... [more ▼]

The efficacy of diatomaceous earth (DE) to control stored-products Coleoptera on stored grain was examined against several populations of the red flour beetle, Tribolium castaneum (Herbst). Four commercially available DE formulations were tested: INSECTO(R), Perma-Guard(TM), Protect-It(R) and the diatomite used for the production of Dryacide(R), each at six concentrations (100-1000ppm). A great variation of efficacy was observed among the DE formulations tested. Protect-It at concentrations up to 400 ppm was found to be the most effective formulation to control red flour beetle populations. However, a concentration of 1000 ppm of Protect-It was necessary to control all adults of all populations. Most T castaneum populations, except one from Ivory Coast (Asm), were more than 90% controlled with INSECTO and Dryacide DE at 600 ppm. At this concentration, about 88% and 22% Asm adults died with INSECTO and Dryacide DE, respectively. Perma-Guard was the least efficient DE formulation to control T castaneum adults with three populations exhibiting some survival at 1000 ppm. Reduced susceptibility to DE was observed in two populations, Asm and Lab susceptible from Kansas (Lab-S). As neither population had been previously exposed to DE, it is suggested that red flour beetles may naturally vary in susceptibility to DE. In addition, it was found that some populations can be satisfactorily controlled with some DE formulations but not with others. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

Effect of ice-nucleating bacteria (Pseudomonas syringae Van Hall) on insect susceptibility to sub-zero temperatures

in Journal of Stored Products Research (1998), 34(1), 81-86

Many stored product insect pests are termed "freeze-intolerant" because they cannot survive ice formation in their extracellular body fluid. In grain silos, the progressive decrease in temperature permits ... [more ▼]

Many stored product insect pests are termed "freeze-intolerant" because they cannot survive ice formation in their extracellular body fluid. In grain silos, the progressive decrease in temperature permits the acclimation of insects and enhances their cold tolerance. The objective of this study was to examine the influence of the concentration of the ice-nucleating-active bacterium Pseudomonas syringae (10, 100 and 1000 ppm), temperature and duration of sub-zero exposure on the cold tolerance of the granary weevil Sitophilus granarius (L.) and the saw-toothed grain beetle Oryzaephilus surinamensis (L.). After an application of 1000 ppm of powdered P. syringae to grain, the mortality of S. granarius and O. surinamensis was increased after 24-h exposure to -4 degrees C. Higher mortality was observed after exposure to colder temperatures and a dose-response relationship was evident. At near-zero (-4 to 0 degrees C) negative temperatures, no dose response was observed, and the mortality in treated grain was the same as that in untreated grain. (C) 1998 Elsevier Science Ltd. All rights reserved. [less ▲]

Biological-Activity Of Fenoxycarb Against Sitophilus-Zeamais Motsch (Coleoptera, Curculionidae)

in Journal of Stored Products Research (1995), 31(1),