Relative toxicity of phosphine against the bean bruchid Acanthoscelides obtectus (Say) (Col., Bruchidae)

Abstract

The toxicity of phosphine against adult Acanthoscelides obtectus (Say) was studied over a range of concentrations, viz. 0.01, 0.0125, 0.015, 0.02, 0.04, 0.08, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 mg/l and exposure periods, viz. 0.25, 0.50, 1, 2, 6, 12, 24 and 48 h at 25°C and 65% relative humidity 3. Results show that both the parameters exhibited significant effects on the mortality of A. obtectus. Data indicate that 100% mortality only occurred in A. obtectus when 1-, 2-and 12-h exposure times were involved in the respective highest individual ct product. The ct products decreased as the exposure times increased for both the mortality levels of 50 and 99%. The minimum ct products for 50 and 99% kill were 0.19 and 0.29 mg h/l, respectively, at an exposure of 12 h. The influence of thresholds on regression equations of the form c n t ¼ k were 0.59 and 13.80 (mg/l) n h for the fixed concentration for 50 and 99% mortality levels, respectively while they were 0.45 and 12.45 (mg/l) n h for the six exposure periods for the same mortality levels.

Bioactivities of Cocos nucifera L. (Arecales: Arecaceae) and Terminalia catappa L. (Myrtales: Combretaceae) leaf extracts as post-harvest grain protectants against four major stored product pests

“…Since harvested crops are vulnerable to insect attack and pest management of these harvested grains is equally as important as that of field crops, it is vital to develop pest control methods to reduce these losses. Currently, control of these pests is primarily dependent upon repeated application of synthetic insecticides (Hasan and Reichmuth 2004). Methyl bromide and phosphine fumigants have been used for decades to control stored pests (Islam et al 2010) and belong to the most effective treatments to protect stored food, feedstuffs, and other agricultural commodities.…”

Direct and admixture toxicity of diatomaceous earth and monoterpenoids against the storage pests Callosobruchus maculatus (F.) and Sitophilus oryzae (L.)

“…Their control is primarily dependent upon repeated application of synthetic insecticides (Hasan and Reichmuth 2004). Methyl bromide and phosphine fumigation has been the method of choice to manage storedproduct insects infesting cereal processing facilities in North America and Europe (Dowdy and Fields 2002).…”

Soft-Electron Beam and Gamma-Radiation Sensitivity and DNA Damage in Phosphine-Resistant and -Susceptible Strains of <I>Rhyzopertha dominica</I>

“…Its use as a safe fumigant of stored products has become even more important with recent restrictions on the production of the main alternative methyl bromide. Widespread resistance to phosphine, however, has emerged in several species of stored-product insects in many countries, which in some instances has caused control failures (Tyler et al 1983, Chaudhry and Price 1990, Collins et al 2002, Rajendran and Gunasekaran 2002, Pratt 2003, Daglish 2004, Hasan and Reichmuth 2004. Phosphine resistance is now known to be present in at least 11 species of stored-product insects in Ͼ45 countries (Chaudhry 2000, Benhalima et al 2004.…”