Larvicidial effects of essential oil and methanol extract of Achillea wilhelmsii C. Koch (Asteraceae) against Anopheles stephensi Liston (Diptera: Culicidae), a malaria vector

Background: Mosquitoes are responsible for the transmission of many pathogens and parasites and consequently serious diseases in humans. Currently, application of plant derivatives has been suggested as an alternative bio-control technique for these medically important vectors. Methods: In this study the essential oil and methanol extract of Achillea wilhelmsii were tested against late-3rd or young-4th instar larvae stages of mosquito vector, Anopheles stephensi, under laboratory condition. The larval mortality was calculated after 24 h of the exposure period. Data were subjected to Probit analysis in order to estimate the lethal concentration for 50% and 90% of mortality values. Results: Results showed that the essential oil induced 100% larval mortality of An. stephensi larvae after 24 h with a dosage of 160 ppm, However, a dosage of 320 ppm of methanol extract was required to reach 100% larval mortality.The essential oil methanol extract exerted significant larvicidal activity with LC50 values of 39.04 and 115.73 ppm, respectively. Conclusion: Our finding suggests that A. wilhelmsii oil is a potential source and has valuable larvicidal compounds for mosquito larval control. © 2017, Kerman University of Medical Sciences. All rights reserved

Detection of cyfluthrin resistance mechanisms among German cockroach strains in vivo in Kashan during 2011-2012

Background: Development of insecticide resistance is a serious problem in the control of German cockroach population in home and hospital. Knowledge about the resistance mechanisms would help us to control the pest. This study was conducted to determine the cyfluthrin resistance in German cockroaches using the piperonyl butoxide (PBO). Materials and Methods: In this study, cyfluthrin (4-6 concentration ranges) was used on susceptible strains- for ten years without any contact with the lab-grown poison - with the mortality rate ranged from 0 to 100. After determining the concentrations of the cyfluthrin in the susceptible strains, the level of susceptibility and resistance mechanism in the wild strains were determined using PBO in vivo. Data were analyzed using Probit program. Results: Lethal dose (LD50) and resistance ratio (RR) for susceptible and three wild strains were 133.43-503.6 and 1.48-3.77, respectively. LD50 of cyfluthrin+PBO and synergist ratio for susceptible and three wild strains were 51.3-490.53 and 1.03-2.43, respectively. Conclusion: All three collected strains showed different levels of resistance compared to the susceptible strains. In almost all strains, PBO considerably increases the cyfluthrin toxicity. The findings signify the involvement of monooxygenase in cyfluthrin resistance

Phytochemical Profile and Mosquito Larvicidal Activity of the Essential Oil from Aerial Parts of Satureja bachtiarica Bunge Against Malaria and Lymphatic Filariasis Vectors

Mosquitoes play an important role in transmission of large number of diseases including malaria, filariasis and arboviral diseases. Increasing application of synthetic insecticides may be resulted in resistant to insecticides. Furthermore, it may have adverse effects on the environment and human health. Currently, one of the most effective alternative approaches under the biological control programs is using of natural larvicidal agents derived from plants. The larvicidal properties of essential oil obtained from the aerial parts of an indigenous plant, Satureja bachtiarica was evaluated against two mosquito vector, Anopheles stephensi and Culex quinquefasciatus. In addition, the analysis of essential oil was investigated by Gas chromatography-Mass spectrometry (GC-MS). Forty-one compounds, representing 98.42% of the essential oils have been identified. The main constituents were carvacrol (22.66%), p-cymene (15.89%), borneol (14.05 %), 1,8-cineole (10.45%) and thymol (7.27%). Five different concentrations of essential oil were evaluated against the late 3rd and early 4th instars larvae of An. stephensi and Cx. quinquefasciatus. The LC50 and LC90 values against An. stephensi larvae were 24.27 and 54.24 ppm and for Cx. quinquefasciatus were 44.96 and 114.45 ppm after 24 hours of exposure, respectively. In conclusion, results of study clearly indicated that the essential oils of S. bachtiarica possessed remarkable larvicidal properties and could serve as an alternative to synthetic insecticides for control of mosquito larvae

Chemical Composition and Mosquito Larvicidal Properties of Essential Oil from Leaves of an Iranian Indigenous Plant Zhumeria majdae

The use of natural products derived from plants in mosquitoes control is an alternative method for minimizing the side effects of chemical pesticides on the environment. In the current study chemical composition of essential oil extracted from an indigenous plant, Zhumeria majdae was determined and identified by gas chromatography (GC) and GC-mass spectrometry (MS) analysis. In addition, the larvicidal activity of essential oil was evaluated against two important mosquito vectors, Anopheles stephensi and Culex quinquefasciatus. Thirty constituents, representing 97.86 of the oil, were identified. The main constituents of the oil were camphor (38.84 ), linalool (31.18 ) and camphene (7.73 ). Z. Majdae volatile oil showed significant toxicity against larvae of both species. The LC50 and LC90 values against An. stephensi larvae were 61.34 and 135.81 ppm and for Cx. quinquefasciatus were 88.51 and 191.56 ppm after 24 hours, respectively. Our findings indicated that the essential oil from Z. majdae leaves may be explored as a potential mosquito bio-larvicide. © 2016 Har Krishan Bhalla & Sons

Utility of Filter Paper for Preserving Insects, Bacteria, and Host Reservoir DNA for Molecular Testing

Background: Appropriate methodology for storage biological materials, extraction of DNA, and proper DNA preservation is vital for studies involving genetic analysis of insects, bacteria, and reservoir hosts as well as for molecular diagnostics of pathogens carried by vectors and reservoirs. Here we tried to evaluate the utility of a simple filter paper-based for storage of insects, bacteria, rodent, and human DNAs using PCR assays. Methods: Total body or haemolymph of individual mosquitoes, sand flies or cockroaches squashed or placed on the paper respectively. Extracted DNA of five different bacteria species as well as blood specimens of human and great gerbil Rhombomys opimus was pipetted directly onto filter paper. The papers were stored in room temperature up to 12 months during 2009 until 2011. At monthly intervals, PCR was conducted using a 1-mm disk from the DNA impregnated filter paper as target DNA. PCR amplification was performed against different target genes of the organisms including the ITS2-rDNA of mosquitoes, mtDNA-COI of the sand flies and cockroaches, 16SrRNA gene of the bacteria, and the mtDNA-CytB of the vertebrates. Results: Successful PCR amplification was observed for all of the specimens regardless of the loci, taxon, or time of storage. The PCR amplification were ranged from 462 to 1500 bp and worked well for the specified target gene/s. Time of storage did not affect the amplification up to one year. Conclusion: The filter paper method is a simple and economical way to store, to preserve, and to distribute DNA samples for PCR analysis

Larvicidal Activity of Essential Oils of Apiaceae Plants against Malaria Vector, Anopheles stephensi

Background: Plant extracts and oils may act as alternatives to conventional pesticides for malaria vector control. The aim of this study was to evaluate the larvicidal activity of essential oils of three plants of Apiaceae family against Anophe­les stephensi, the main malaria vector in Iran. Methods: Essential oils from Heracleum persicum, Foeniculum vulgare and Coriandrum sativum seeds were hydro distil­lated, then their larvicidal activity were evaluated against laboratory-reared larvae of An. stephensi according to stan­dard method of WHO. After susceptibility test, results were analysis using Probit program. Results: Essential oils were separated from H. persicum, F. vulgare and C. sativum plants and their larvicidal activi­ties were tested. Result of this study showed that F. vulgare oil was the most effective against An. stephensi with LC50 and LC90 values of 20.10 and 44.51 ppm, respectively. Conclusion: All three plants essential oil can serve as a natural larvicide against An. stephensi. F. vulgare oil exhib­ited more larvicidal properties

Detection of bendiocarb and Carbaryl resistance mechanisms among German cockroach Blattella germanica (Blattaria: Blattellidae) collected from Tabriz Hospitals, East Azerbaijan Province, Iran in 2013

Background: Insecticide resistance is one of the serious problems for German cockroach control program. This study was conducted to determine the bendiocarb and Carbaryl resistance mechanisms in German cockroaches using the piperonyl butoxide (PBO). Methods: Bioassay tests were conducted with 4 to 6 different concentrations of both insecticides with four replicates of 10 susceptible strain cockroaches per concentration to determine of discriminative concentration. After determining discriminative concentration, the result was compared to wild strain. The levels of susceptibility and resistance ratio (RR) and synergism ratio (SR) were calculated for each five wild strains. Moreover resistance mechanisms in wild strains were determined using PBO synergist in vivo. Results: Hospital strains showed different levels of resistance to bendiocarb and carbaryl compared to susceptible strain. The bendiocarb and carbaryl resistance ratios ranged from 2.11 to 7.97 and 1.67 to 2 at LD50 levels, respectively. The synergist PBO significantly enhanced the toxicity of bendiocarb and carbaryl to all strains with different degrees of synergist ratio, 1.31, 1.39, 3.61, 1.78, 1.62 and 2.1 fold for bendiocarb, 1.19, 1.18, 1.12. 1.29, 1.45 and 1.11- fold for carbaryl, suggesting monooxygenase involvement in bendiocarb and carbaryl resistance. Conclusion: The synergetic effect of PBO had the highest effect on bendiocarb and resistance level was significantly reduced, which indicates the important role of monoxidase enzyme in creating resistance to Bendiocarb. Piperonyl butoxide did not have a significant synergistic effect on carbaryl and did not significantly break the resistance

Molecular Detection of Leishmania infantum in Naturally Infected Phlebotomus perfiliewi transcaucasicus in Bilesavar District, Northwestern Iran

Background: Visceral leishmaniasis is caused by Leishmania infantum, transmitted to humans by bites of phle­botomine sand flies and is one of the most important public health problems in Iran. To identify the vector(s), an investiga­tion was carried out in Bilesavar District, one of the important foci of the disease in Ardebil Province in northwest­ern Iran, during July-September 2008. Methods: Using sticky papers, 2,110 sand flies were collected from indoors (bedroom, guestroom, toilet and stable) and outdoors (wall cracks, crevices and animal burrows) and identified morphologically. Species-specific amplifica­tion of promastigotes revealed specific PCR products of L. infantum DNA. Results: Six sand fly species were found in the district, including: Phlebotomus perfiliewi transcaucasicus, P. pa­patasi, P. tobbi, P. sergenti, Sergentomyia dentata and S. sintoni. Phlebotomus perfiliewi transcaucasicus was the domi­nant species of the genus Phlebotomus (62.8%). Of 270 female dissected P. perfiliewi transcuacasicus, 4 (1.5%) were found naturally infected with promastigotes. Conclusion: Based on natural infections of P. perfiliewi transcaucasicus with L. infantum and the fact that it was the only species found infected with L. infantum, it seems, this sand fly could be the principal vector of visceral leishmani­asis in the region.