جستجوی مقالات مرتبط با کلیدواژه "tribolium castaneum" در نشریات گروه "کشاورزی"

Continues use of synthetic insecticides has resulted in many serious problems, such as the development of insect resistance, toxicity to non-target organisms and environmental pollution. Thus, there is a necessity for effective and safe alternatives which can control stored grain pests infestation. This study was conducted to evaluate the insecticidal activity of two plant extracts, ginger, Zingiber officinale and myrtle, Myrtus communis separately and in combination against adult of red flour beetle, Tribolium castaneum. The plant extracts prepared by using Soxhlet Extractor and Ethyl alcohol as solvent. Three concentrations (2.5%, 5%, and 7.5%) of each plant were prepared. We placed 0.5 mL of each concentration on filter paper in petri dish, in addition to the control treatment. Ten adult insects were put into each petri dish. The mortality rate was recorded at 24, 48 and 72 h after treatment. The results indicated that the mortality was varying from plant to plant as flowing: M. communis reached its maximum value of 3.33% at 7.5 g mL-1 after 72 h. In the case of Z. officinale, it was 4% at 7.5 g mL-1 after 72 h, while the mixture of Z. officinale and M. communis reached its maximum value (4%) at 7.5 g mL-1 after 48 h exposure time. Relationship between exposure time and concentrations on mortality of T. castaneum indicated that mortality was increased by elevating the concentration and exposure time. The results of the present study revealed that by considering the mean mortality as a main index, the combination of Z. officinale and M. communis was the most toxic, while M. communis the least toxic. Results suggested that the combination of the two extracts could become interesting alternative to conventional chemical insecticides against stored grain pests.

Isolates were identified by molecular and morphological tests, including coleopteran-specific cry genes in the Iranian native Bacillus thuringiensis collection. Spherical and irregular shapes were observed to be the most frequent shapes using Coomassie brilliant blue staining. PCR analysis with universal and specific primer pairs was used to detect coleopteran-specific cry genes such as cry1I, cry3, cry7, cry18, and cry26. All the isolates contained at least one active coleopteran-cry gene, while the most abundant isolates had cry26 and cry18 genes. The patterns of protein size were characterized in addition to their insecticidal activity against third-instar larvae of Tribolium castaneum. Protein profiles produced bands that varied from 14-180 kDa. Four native isolates containing coleopteran-active cry genes displayed higher activity against T. castaneum larvae than B. thuringiensis subspecies galleriae as a reference strain. The median lethal concentration (LC50) of the most pathogenic isolate, PS1078, was 2.72 × 106 spores/ml. Its 16S rDNA gene sequence analysis demonstrated similarity to B. thuringiensiss subspecies galleriae. The characterization of isolates provided useful data for selecting new isolates to expand novel bio-insecticidal products.

The red flour beetle, Tribolium castaneum (Herbst), is one of the most destructive pests attacking stored grain products all over the world. Serious problems assossiated with using synthetic chemical insecticides have strongly demonstrated the need for applying alternative safe compounds such as plant essential oils. The present experiment was conducted to evaluate fumigant toxicity of essential oils from the fresh fruit peel of two Citrus species namely, Citrus sinensis (L.) Osbeck and Citrus paradisi (Macfarlane) against 1 to 7-days-old adults of T. castaneum under laboratoryconditions. Moreover, oviposition deterrence activity of sublethal concentrations of the oils were assessed on the female beetles. All experiments were carried out at 27 ± 1 °C and65 ± 5% r. h. in darkness. Findings indicated the high fumigant toxicity of both essential oils. According to probit analysis, there was no significant differences between C. sinensis (LC50 = 7.27 µl.l-1 air) and C. paradisi (LC50 = 7.70 µl.l-1 air) essentialoils. Also, oviposition deterrence activity of the essential oils was significantly increased as concentrations of the oils were increased from 500 to 2500 ppm. In general, the results of our study demonstrated the high efficacy of C. sinensis and C. paradisi oils against T. castaneum.

Beauveria bassiana (Balsamo) Vuillemin is an important natural regulator of insect populations. Identification of a suitable molecular marker for detecting a virulent phenotype on a target pest would be useful in screening for effective isolates against the pest. Nine isolates of B. bassiana were tested for their virulence to adults of Tribolium castaneum (Herbst) in laboratory bioassay with 1×108 conidia mL-1. DNA markers provide more detailed genomic information.DNA fingerprints were generated by RAPD markers. Fungal DNA was extracted by CTAB. Twelve random oligonucleotide primers were used for amplification. After bioassay, three arbitrary categories of isolates were chosen i.e. isolates that caused > 45%, 45-30% and < 30% mortality, and were classified as highly (H), moderately (M), and less (L) virulent isolates based on average mortality, respectively. Also, based on LT50 values, three arbitrary categories were chosen i.e. isolates with < 80 h, 80-100 h and > 100 h LT50 values, and were classified as highly (H), moderately (M), and less (L) virulent isolates, respectively. The results of bioassay showed that isolates IRAN 440C and DEBI 004 were the causative agents of mycoses with the highest and lowest lethal effect, respectively. The lowest LT50 value was related to DEBI 014. Cluster analysis of the RAPD data showed four clusters according to similarity, following cluster analysis using the Jaccard similarity coefficient and clustering was done using un-weighted pair group method with arithmetic (UPGMA). The results showed that there was genetic diversity between these isolates, but the groups based on virulence rating and LT50 values did not match with the RAPD clusters completely.

Effect of controlled atmospheres (CAs) at various concentrations of CO2, N2 and O2 on the lethal times of Tribolium castaneum and Trogoderma granarium was investigated at 20 and 30 ºC. Experiments were performed using a recirculatory multi-flask apparatus. The results revealed that, the shortest times (0.1, 0.3 and 0.9 day for adults, larvae and pupae, respectively) required to obtain 50% mortality of T. castaneum stages were at 100% CO2 followed by 75% CO2, 50% CO2, 99% N2 + 1% O2 and 25% CO2, at higher tested temperature (30 °C). Adults were more sensitive to the different treated CAs than larvae, pupae the most tolerant stages. Diapausing larvae of T. granarium were the most tolerant to all treated CAs at tested temperature degrees. The effectiveness of CAs to decrease its LT50 values were 100% CO2 followed by 99% N2 + 1% O2 and 98% N2 + 2% O2 at 30°C. It may be concluded that diapausing larvae are more difficult to control with CAs than normal larvae. A treatment with N2 relying on the absence of O2 will take a longer treatment time to control the diapausing larvae and in late winter, exposure times needed for control may be even longer. If CAs were to be applied under such circumstances, a high content of CO2 would be the best option to achieve control in a comparatively short time.

Certain compounds of plants such as essential oils, with insecticidal properties have been considered as alternatives to chemical pesticides for pest control. This study reports the fumigant toxicity of Citrus reticulata Blanco (Rutaceae) peel essential oils against stored-product insect pest, red flour beetle, Tribolium castaneum Herbst (Tenebrionidae) adults. Experiment was carried out at 27 ± 1 °C and 60 ± 5 % relative humidity in darkness. Experimental concentrations were 15, 22, 31, 45, and 63 μl/l air tested on adult (1-7 days old) insects after 24 and 48 h of exposure. Results indicated that essential oils from C. reticulata had fumigant tocxicity effects against this stored pest. LC50 values were 38.2 and 35.6 μl/l air at 24 and 48 h after exposure of T. castaneum adults respectively. The essential oils of Citrus reticulata fruit peels at the highest dose of 63 μl/l air caused 76.6 % and 79 % mortality of insects after 24 and 48 hours of exposure, respectively. Mortality of T. castaneum increased with both increase in concentration of C. reticulata oils as well as exposure time of treated insects. These results suggest the potencial of C. reticulata oil as a control agent against T. castaneum.