Susceptibility of different populations of Tribolium confusum (Coleoptera: Tenebrionidae) to malathion (EC 57%) in flour mills of Iran

The confused flour beetle, Tribolium confusum, is a key pest of stored products such as wheat and flour. For decades, organophosphorus compounds, such as malathion and pirimiphos-methyl, have been applied against stored-product pests. In this research, susceptibility of different populations of T. confusum, collected from silos at different locations of Iran, against malathion (EC 57%), was studied in the laboratory, based on a completely randomized design. Based on pre-tests, the Bioassay Index Dose was estimated as 2 g a.i./m2. Out of 23 populations, 2 populations from Bandar-Abbas region were resistant populations against malathion (9.72% and 67.2% mortality), while one population from Khomein region was moderately resistant (86.08% mortality), and the rest of the population were susceptible to malathion (95.71% to 100% mortality). Therefore, in warm locations of Iran, where this pest has evolved resistance against malathion, other control measures shall be considered

Effects of imidacloprid, dichlorvos, pymetrozine and abamectin, on life table parameters of the predatory bug, Orius albidipennis (Hemiptera: Anthocoridae)

Effects of four pesticides (imidacloprid, dichlorvos, pymetrozine and abamectin) were evaluated on life table parameters of Orius albidipennis (Reuter). Pesticides were used at the concentrations recommended by the manufacturers. The bioassays were carried out using drum-cell method, in a growth chamber at 27 ± 1ºC, R.H. of 65 ± 5% and 16 h photo phase. The net reproductive rate (R0) value for the populations treated with imidacloprid, dichlorvos, pymetrozine, abamectin and tap water as control was, 2.91 ± 0.48, 18.85 ± 2.55, 10.16 ± 1.21, 8.00 ± 1.05, 43.40 ± 7.64; the intrinsic rate of natural increase (rm) was 0.040 ± 0.005, 0.097 ± 0.018, 0.086 ± 0.012, 0.078 ± 0.010, 0.148 ± 0.006: the mean generation time (T) was 25.60 ± 1.12, 25.94 ± 1.85, 26.37 ± 0.25, 25.61 ± 0.21, 25.20 ± 1.16; the doubling time (DT) was 18.04 ± 2.76, 7.72 ± 1.60, 8.23 ± 1.11, 9.24 ± 1.37, 4.68 ± 0.18, and the finite rate of increase (λ) was 1.041 ± 0.006, 1.102 ± 0.019, 1.090 ± 0.013, 1.081 ± 0.011, 1.160 ± 0.007, respectively. Imidacloprid and dichlorvos, which revealed the most and the least effects on the life table parameters, were the most and the least harmful among the chemicals tested

Comparative toxicity of abamectin, cyromazine and spinosad against the leaf-miner fly, Liriomyza sativae (Dip.: Agromyzidae)

The leaf-miner fly, Liriomyza sativae (Blanchard), is one of the major insect pests of vegetable crops in Iran and other countries. To determine the toxicity (LC50) of bioinsecticides abamectin 1.8% EC, cyromazine 75% WP and spinosad 24% SC against L. sativae, bioassay was done on its larval and adult stages under 25 ± 1°C, 65 ± 5% R.H. and a photoperiod of 16: 8 (L: D). The LC50 values found to be 1.5, 1.8, 14.3 ppm for abamectin, 34.8, 38.4, 1295 ppm for cyromazine and 4.4, 12.1, 13.7 ppm for spinosad against the first and last larval stages as well as the adults of L. sativae, respectively. The toxicity of the insecticides on the larval stages was higher than on adults. Using a mixture of petroleum oil, as a synergist, and the insecticides significantly increased the mortality of the first instar larvae. The results indicated that cyromazine is ineffective for the control of adults, while it is proved to be effective against the leaf-miner's larval stages. It is found that abamectin and spinosad are more efficient insecticides than cyromazine for the control of all developmental and adult stages of L. sativae

Compatibility of the entomopathogenic fungus Beauveria bassiana with the insecticides fipronil, pyriproxyfen and hexaflumuron

The compatibility of Beauveria bassiana isolate DEBI 002 (Atashgah) with fipronil, pyriproxyfenand hexaflumuron insecticides was assayed. To determine the impact of the insecticides on thegermination of the fungal spore, different concentrations of the compounds were added to the culturemedium (malt agar). In order to calculate the mycelial growth in different treatments, each colonydiameter was measured and the spores were counted in the surface area to assess its sporulation. Theresults showed that pyriproxyfen at 1500 ppm and hexaflumuron at 80 ppm completely inhibited mycelialgrowth, while the inhibitory effect of fipronil at 1600 ppm remained at 76.6%. The inhibitory effect oflower concentrations of all three insecticides was between 10 and 20%. All tested insecticides inhibitedthe spore production between 80 to 100% at the highest concentrations without any significantdifferences. Pyriproxyfen at 400 ppm and hexaflumuron at all concentrations completely inhibited sporegermination, with significant difference, comparing with the rest of treatments. The results indicate thathexaflumuron has the highest inhibitory effect on the spore germination and is not recommended to beused simultaneously with B. bassiana against the insect pests

Accuracy and efficiency of conventional ground sprayers in Iran

Sunn pest, Eurygaster integriceps, is a key pest of wheat and barley in Iran. At present, infested areas are treated with ground sprayers. A survey was conducted to evaluate the efficiency and calibration accuracy of ground hydraulic sprayers in Iran. The results showed that the motorized lance sprayer and manually operated sprayer were the most conventional sprayers, and fenitrothion EC 50% and deltamethrin EC 2.5% were the conventional insecticides against sunn pest in Kermanshah province. The mean efficacy percentage was 88% and 35% against nymphs and overwintered adults, respectively. In motorized lance sprayers, there were 5% and 90% overdosage of fenitrothion and deltamethrin, respectively; while, in manually carried sprayers, there were 5% and 25% overdosage of fenitrothion and deltamethrin, respectively. Applied dosages were 5-20% and 25-90% more than recommended dosages of fenitrothion and deltamethrin, respectively. Errors in effectiveness and applied dosage were higher in motorized lance sprayer than manually carried sprayers

Compatibility of the entomopathogenic fungus Beauveria bassiana with the insecticides fipronil, pyriproxyfen and hexaflumuron

Abstract The compatibility of Beauveria bassiana isolate DEBI 002 (Atashgah) with fipronil, pyriproxyfen and hexaflumuron insecticides was assayed. To determine the impact of the insecticides on the germination of the fungal spore, different concentrations of the compounds were added to the culture medium (malt agar). In order to calculate the mycelial growth in different treatments, each colony diameter was measured and the spores were counted in the surface area to assess its sporulation. The results showed that pyriproxyfen at 1500 ppm and hexaflumuron at 80 ppm completely inhibited mycelial growth, while the inhibitory effect of fipronil at 1600 ppm remained at 76.6%. The inhibitory effect of lower concentrations of all three insecticides was between 10 and 20%. All tested insecticides inhibited the spore production between 80 to 100% at the highest concentrations without any significant differences. Pyriproxyfen at 400 ppm and hexaflumuron at all concentrations completely inhibited spore germination, with significant difference, comparing with the rest of treatments. The results indicate that hexaflumuron has the highest inhibitory effect on the spore germination and is not recommended to be used simultaneously with B. bassiana against the insect pests