SummaRyResidual activity of EC formulations of two insecticides, cypermethrin (combined with the synergist piperonyl butoxide) and pirimiphos-methyl, against Sitophilus granarius (L.) adults and Plodia interpunctella (Hübner) larvae was investigated on concrete surface. The experiment was run indoors at 16-24ºC temperature and 30-60% r.h. by applying water solutions of products based on cypermethrin (48 mg AI/m 2 ) and pirimiphos-methyl (750 mg AI/m 2 ) to concrete surface. Insect mortality was estimated after 2, 7 and 14 days of insect exposure to treated concrete and 7 days of recovery on untreated coarse wheat meal at 24-26ºC and 55-65% r.h in the laboratory.High efficacy of cypermethrin against S. granarius adults (87-100%) and P. interpunctella larvae (84-100%) was detected after 14 days of exposure to all deposits on concrete surface. Pirimiphos-methyl achieved maximum efficacy (100%) in all treatments of S. granarius adults and P. interpunctella larvae after 2 and 14 days of exposure, regardless of deposit age. After 7 days of recovery, the efficacy of both insecticides mostly increased, especially of cypermethrin, up to around 50% after two days of exposure, up to 24-45% after seven days of exposure and up to 15% after 14 days of exposure. The results show that the EC formulations of cypermethrin and especially of pirimiphos-methyl were highly effective in controlling S. granarius adults and P. interpunctella larvae over a period of 60 days following application to concrete surface.
Residual efficacy of the insecticide deltamethrin, an EC formulation containing 25 g/L AI + 225 g/L PBO (piperonyl butoxide synergist), against lab populations of Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum and Sitotroga cerealella was investigated in the laboratory by applying product water solutions (0.25 mg AI/kg) to wheat grain (at 25±1°C and 60±5% r.h.). Adult mortality on 0, 7, 14 and 30 days old deposits was estimated after 2, 7 and 14 days of exposure to treated wheat grain and additional 7 days of recovery. Progeny reduction (PR, %) was also assessed. After 2 days of exposure to deposits of all ages, deltamethrin caused only 0-10% mortality of coleopterans (up to 37% after the recovery period) and 23-30% of S. cerealella, while mortality before and after recovery from 14 days of exposure was 95-50% for S. oryzae, 97-100% for R. dominica, 99-100% for T. castaneum and 100% for S. cerealella. Progeny production of S. oryzae was highest after parents contacted with 14 days old deposit of deltamethrin (PR, 76%), and lowest after contact with fresh deposit (PR, 95%), while R. dominica and T. castaneum had no progeny on any deltamethrin deposit age in wheat (PR, 100%), and S. cerealella had only a very low progeny (PR, 99%). The results showed that the synergised deltamethrin, applied at 0.25 mg/kg in wheat grain, is a highly effective insecticide for storedproduct insect control, while a higher dose is required for successful residual control of S. oryzae.
SUMMARYThe efficacy of spinosad and abamectin against T. castaneum adults from a laboratory population with normal susceptibility to contact insecticides and against malathion-resistant populations from Nikinci and Jakovo was tested in the laboratory (25±1ºC and 60±5% r.h.). The insecticides were applied to 500 g of untreated wheat grain for each of the following application doses: 0.25, 0.5, 1.0, 2.5 and 5.0 mg a.i./kg. After treatment, wheat was divided into three equal subsamples and 50 T. castaneum adults from each of the three test populations were released the next day into jars for each dose. Mortality was evaluated after 7, 14 and 21 days of exposure to treated wheat grain.Generally, higher concentrations and longer exposure periods resulted in higher efficacy of both insecticides, but abamectin was significantly more effective than spinosad against all three tested populations. After 7 days of exposure, mortality did not exceed 30% in any test variant. Fourteen days after treatment with the highest dose (5 mg/kg) of spinosad, mortality was highest (75%) in the laboratory population, while treatment with the same dose of abamectin achieved the highest mortality (58%) in the laboratory and Jakovo populations. After 21 days, spinosad applied at the rate of 5 mg/kg was most effective (97% mortality) in the laboratory population, while 88% efficacy was recorded in Jakovo population and 87% in Nikinci population. Abamectin doses of 2.5 and 5 mg/kg caused high adult mortality of 94-100% in the laboratory and Jakovo populations, and a significantly lower mortality in Nikinci population (75 and 86%, respectively). Statistically significant differences in the efficacy of spinosad, and particularly of abamectin, were detected among the three tested populations, the greatest difference being between the laboratory and Nikinci populations, which clearly indicates that resistance of T. castaneum adults to malathion had a significant influence.
Laboratory bioassays were conducted to detect possible alteration in susceptibility of two field Tribolium castaneum (Herbst) populations (sampled in a warehouse in Nikinci and a silo in Jakovo) to dichlorvos, malathion, chlorpyrifos-methyl, pirimiphos-methyl, deltamethrin and bifenthrin after previous selection with the LD80 of pirimiphos-methyl and deltamethrin. Data from the topical application bioassays show that chlorpyrifos-methyl was the most toxic insecticide to T. castaneum adults of the Nikinci population selected with pirimiphosmethyl and deltamethrin, while malathion was the weakest, and both selection procedures changed/reduced significantly only the toxicity of deltamethrin and bifenthrin, increasing their resistance ratios (RR) at the LD50 from 1.1 to 1.8 (bifenthrin) and from 0.9 to 2.2 (deltamethrin). Deltamethrin was the most toxic insecticide for Jakovo adults selected with the LD80 of pirimiphosmethyl, while malathion was again the least toxic. Selection of that population had no effect on insecticide toxicity, except of malathion, which had a rise in RR at the LD50 from 26.0 to 29.8. [Projekat Ministarstva nauke Republike Srbije, br. III 46008]
The presence of the invasive coccinellid Harmonia axyridis in aphid colonies on plants, as well as its co-occurrence with native coccinellid predators was studied in the period 2011-2020. Also, its occurrence on fruit plants and grapes was monitored at harvest time. Research was conducted on 41 locations in Serbia. The feeding of this invasive species was recorded on a total of 43 aphid taxa of 25 different genera. It was most frequently present on aphid colonies of the genera Aphis, Brachycaudus and Myzus. The presence of H. axyridis in aphid colonies was recorded on 58 cultivated plant species: 10 fruit, 7 field crop, 5 vegetable and 16 ornamental species, as well as 20 non-cultivated plants. Harmonia axyridis feeding was also observed on mature fruit plants of cultivated blueberries, nectarine and grapes in representative production areas in Serbia. Nine native coccinellid species were detected in this study: Adalia bipunctata, Adalia decempunctata, Coccinella septempunctata, Hippodamia sp., Hippodamia apicalis, Hippodamia variegata, Hippodamia tredecimpunctata, Hippodamia undecimnotata and Propylea quatuordecimpunctata. Populations of H. axyridis and native coccinellids co-occurred in aphid colonies on many plants, i.e. in 53.45% of all samples. The results inferred that H. axyridis as a predator of numerous aphids on many plants is a useful coccinellid species. However, it may also be considered as a potential pest in fruit and grape production, and a threat to native aphidophagous coccinellids.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.