Showing 4 results for A. A. Pourmirza
A. A. Pourmirza, M. Tajbakhsh,
Volume 6, Issue 3 (fall 2002)
Abstract
Due to the need for new fumigants to control insects that attack food commodities, the toxicity of acetone was determined on some species of stored pest insects in Urmia University in the year 2000. In empty space tests, the LC50 values of acetone for Oryzaephilus surinamensis (L.), Callosobruchus maculatus (F.), Tribolium confusum (Duv.) and Sitophilus granarius (L.) were 15.40, 15.51, 17.55 and 18.26 μl/liter, respectively. The experiments of acetone penetration to wheat mass revealed that the application of acetone in headspace led to the penetration of acetone vapours into the wheat mass and killing the S. granarius and T. confusum had been concealed in interkernel space. The comparison of LC50 values of empty space tests with LC50 values of penetration experiments revealed that the increase in penetration toxicity was 8.63 fold for S. granarius. A similar trend was observed for T. confusum adults. In hidden infestation tests, the application of acetone to the headspace resulted in destroying the developmental stages of S. granarius concealed in wheat and achieved 75% mortality at a dose of 160 μl/liter during seven weeks. Acetone showed no deleterious effects on the germination and vigor of wheat seeds.
P. Namvar, M. H. Safaralizadeh, A. A. Pourmirza,
Volume 7, Issue 1 (spring 2003)
Abstract
In this study, susceptibility of the first three larval stages of Spodoptera exigua to Bacillus thuringiensis was investigated. To determine the LC50 values for each larval instar, 6 different logarithmic concentrations of Bacillus thuringiensis were used. A control was also included in each of the bioassays. The value of LC50 for 1st instar larvae, that had been treated one to four hours after hatching, was 311.617 ppm. For the 2nd and third instars, the larvae values of LC50 were 1356.95 and 2708.27 ppm, respectively. It was clear that larval susceptibility to Bacillus thuringiensis decreased with age. In order to enhance the Bacillus thuringiensis efficiency to control Spodoptera exigua under field conditions, Bacillus thuringiensis should be applied at egg hatch peaks.
A. Sheikhi Garjan, K. Talebi, A. A. Pourmirza,
Volume 8, Issue 4 (winter 2005)
Abstract
The egg parasitoids are the major natural enemies of sunn pest and application of selective insecticides is one of the strategies for conservation of natural enemies. The toxicity of five different insecticides used in cereal fields to the parasitized eggs was investigated under laboratory conditions. The insecticide solutions were made based on the recommended field rates. 3-, 5- and 8- day -old parasitized eggs were dipped into insecticide solutions.
Among the treated developmental stages (except for the fenirothion), 3- and 8- day- old parasitized eggs showed the highest and the lowest emergence percentages, respectively. Deltamethrin had maximum effect on emergence percentage whereas phosalone had the least hazardous effects. There was a significant difference in parasitism percentage between 3- and 8- day- old parasitized eggs in each of the 4 treatments, viz trichlorphon, fenitrothion, deltamethrin and esfenvalerate. Adults emerging from 3- day- old eggs parasitised less eggs than those emerged from 8- day- old eggs in fenitrothion, and trichlorphon treatments. All tested insecticides were highly toxic to the adult parasitoid, causing 100% mortality when the adults were exposed to sprayed areas at recommended rates.
E. Javvi, M. H. Safar Ali Zadeh, A. A. Pourmirza,
Volume 8, Issue 4 (winter 2005)
Abstract
The effect of Bacillus thuringiensis var. kurstaki on different larval instars of Colorado potato beetle, Leptinotarsa decemlineata (Say) and the role of two plant materials, namely, caffeine and aqueous neem extract, in the enhancement of it’s efficiency was investigated under laboratory conditions. The experiments were conducted at 25±4 oC, 65±5 %(RH) and photoperiod of 16:8 (L:D).The larvae were provided from the colony established and maintained on host plant. The different larval instars were distinguished by measuring head capsule width.To evaluate susceptibility of different instar groups of larvae to B.thuringiensis, LC50 values on (1-4) instar groups were determined. LC50 values for 1st, 2nd, 3rd and 4th instar groups were, 183.86, 377.03 ,1297 and 3096 ppm, respectively. The synergistic effect of caffeine and aqueous neem extract with B.thuringiensis was investigated separately on 3rd larvae instar. A completely randomized design with 6 treatments and 4 replications was used. The results revealed that there was a striking synergistic effect of caffeine and neem on B.thuringiensis.The larval mortality percentage for mixture 618ppm of B.thuringiensis and 4000ppm of caffeine was 80% however, this was 10% and 20% for caffeine B. thuringiensis respectively when these compounds were used alone.The initiation of larval mortalitry in all mixtures was earlier than other treatments.Also the larval mortality for mixture B. thuringiensis with 35000 ppm of aqueous neem extract was 77.5% after 144 hours however, it was 22.5 % and 25 % for B.t. and neem alone, respectively. The mean weight of larvae treated with all synergists was significantly less than the control cohort, (p<0.05).
