The insecticidal effect of diatomaceous earth against adults and nymphs of Blattella germanica

Objective: To evaluate the insecticidal effect of diatomaceous earth (DE) against adults and nymphs of Blattella germanica.Methods:cockroaches. Two stages, nymph and adult, were exposed to six dose rates of the DE, 2.5, 5, 10, 15, 20 and 25 g/m2, at 24, 48 and 72 h exposure period. Mortality (number of dead cockroaches) was assessed after 24 h. Other exposed specimens were transferred to the beakers contained food and water for counting the retard mortality rate after 1 week. This cross sectional study has been done on the laboratory strain of German Results: Increasing in dose rates of DE increased mortality rate, so that the lowest and highest mortality rates were observed in 2.5 and 25 g/m2, respectively. The results of the statistical analysis showed no significant difference in the lethality of 50% of DE plus water on the German cockroach nymphs.Conclusions:Due to the resistance of German cockroach against organochloride organophosphorus, carbamate and pyrethriodes insecticides, it is suggested to use DE for insect’s control.

Larvicidal activity of essential oil and methanol extract of Nepeta menthoides against malaria vector Anopheles stephensi

OBJECTIVE@#To investigate the larvicidal activity of essential oil and methanol extract of the Nepeta menthoides (N. menthoides) against main malaria vector, Anopheles stephensi (An. stephensi).@*METHODS@#The essential oil of plant was obtained by Clevenger type apparatus and the methanol extract was supplied with Percolation method. Larvicidal activity was tested by WHO method. Twenty five fourth-instar larvae of An. stephensi were used in the larvicidal assay and four replicates were tested for each concentration. Five different concentrations of the oil and extract were tested for calculation of LC(50) and LC(90) values.@*RESULTS@#The LC(50) and LC(90) values were determined by probit analysis. LC(50) was 69.5 and 234.3 ppm and LC(90) was 175.5 and 419.9 ppm for the extract and essential oil respectively.@*CONCLUSIONS@#According to the results of this study methanolic extract of plant exhibited more larvicidal activity than essential oil. This could be useful for investigation of new natural larvicidal compounds.

Bioassay evaluation on the efficacy of α-cypermethrin impregnated into long lasting insecticide treated nets using Anopheles stephensi

OBJECTIVE@#To evaluate the bioefficacy of α-cypermethrin impregnated into long lasting insecticide treated nets (LLITNs-INTERCEPTOR®) against main malaria vector, Anopheles stephensi (An. stephensi).@*METHODS@#The effectiveness of bed net impregnated with α-cypermethrin (INTERCEPTOR®) with washing was evaluated. The washing procedure and bioassay tests were carried out according to the WHO-recommended methods. Malaria vector, An. stephensi was exposed to impregnated bed net for three minutes and then mortality measured after 24 h recovery period. Knockdown was also measured according to the logarithmic times.@*RESULTS@#Result of cone bioassay method showed that bioefficacy of α-cypermethrin decreased from 100% in unwashed to 15% in 20 washes. KT(50) was measure as one minute in one wash and increased to 40 min in 20 washes.@*DISCUSSION@#Findings of this study provide guideline for malaria vector control authorities and people using pyrethroid-impregnated bed nets.

Larvicidal activity of marine algae, Sargassum swartzii and Chondria dasyphylla against malaria vector Anopheles stephensi.

Objectives: The objective of this study was to evaluate larvicidal activity of native marine algae against main malaria vector Anopheles stephensi. Study design: The total 70% methanol (MeOH) extract and partition fractions of chloroform (CHCl3), ethylacetate (EtOAc), and MeOH from two algae, Sargassum swartzii and Chondria dasyphylla were investigated for larvicidal activities against late III and early IV instar larvae of malaria vector An. stephensi. Results: Among all the fractions tested against larvae, EtOAc fraction of S. swartzii and C. dasyphylla, showed mortality rate of 96 and 95%, respectively. Probit analysis of logarithmic concentration from regression line exhibited the LC50 and LC90 values of 11.75 and 53.47 ppm respectively for S. swartzii and 10.62 and 56.39 ppm respectively for C. dasyphylla. Conclusion: This is the first report of larvicidal activities of two native algae against An. stephensi. We propose that the larvicidal activity of EtOAc fraction is related to the presence of semi-polar compounds. Further isolation and purification could lead to identify more potent compounds.

Crimean--Congo hemorrhagic fever: a molecular survey on hard ticks (Ixodidae) in Yazd province, Iran

OBJECTIVE@#To determine the rate of Crimean--Congo hemorrhagic fever virus (CCHFV) infection in hard ticks (Ixodidae) in Yazd province of Iran.@*METHODS@#A molecular survey on hard ticks (Ixodidae) was conducted in Yazd province during 2008-2009. A total of 140 hard ticks (three genera and 7 species) were collected from randomly selected villages and were exanimate for presence of CCHFV reverse transcription--polymerase chain reaction (RT-PCR) method.@*RESULTS@#CCHFV genome was found in 5.71% of hard ticks. All positive ticks were from Hyalomma genus. Positive ticks including: Hyalomma dromedarii, Hyalomma marginatum, Hyalomma anatolicum, Hyalomma detritum, Hyalomma asiaticum. We were not able to find virus in in Rhipicephalus sanguineus and Dermacentor marginatus. Results exhibited that Hyalomma is the main vector in the study area.@*CONCLUSIONS@#Due to the presence of virus in 24 provinces' out of 31, we recommend the use of acaricides and repellent to prevent disease transmission among humans. Greta care should be taken by the people who are working in slaughter houses.

Demonstration of malaria situation analysis, stratification and planning in Minab District, southern Iran

OBJECTIVE@#To demonstrate malaria situation analysis, stratification and planning for an endemic area in southern Iran.@*METHODS@#Data on health system, population, meteorological parameters, malaria cases, anopheline vectors, and control activities during 2005-2007 was obtained from Minab Health Center, Minab Meteorological Station and published documents about malaria elements in the study area. A datasheet was created in excel 2003 for analysis.@*RESULTS@#There were 644 health staff working in Minab District including 99 health staff in malaria control program. The health facilities are distributed as follow: 1 hospital with 96 beds, 23 health centers including private centers (10 in Minab city and 13 in rural area of Minab District) and 119 health houses in rural areas of Minab District. A nopheles stephensi was the dominant species in Minab District, however, Anopheles dthali, Anopheles superpictus, Anopheles fluviatilis, Anopheles multicolor, Anopheles pulcherrimus and Anopheles turkhudi can also be found in the area. Anopheles stephensi was reported susceptible to malathion, propoxur, primphos-methyl, lambda-cyhalothrin permethrin and deltamethrin, and resistant to DDT and dieldrin in the area. During the study period a total of 10 665 positive cases were reported, mainly due to local transmission (99.6%). Plasmodium vivax was the main causative agent followed by Plasmodium falciparum. There were reports about drug resistance of Plasmodium falciparum in the area.@*CONCLUSIONS@#Using different parameters, Minab was classified into 3 strata. A plan was designed based on described goal, objectives and targets. The approaches of this plan were categorized into: health education, early detection and correct treatment, and vector control. Main constraints of these approaches are population movement between Iran, Pakistan and Afghanistan; vector control challenges at district, inadequate skilled medical staff in malaria case management and weak inter-sectorial coordination for malaria control, especially in urban areas.

Fabrication of an olfactometer for mosquito behavioural studies.

Background & objectives: Olfaction is the major sensory modality involved in the resource searching behaviour of insects including vector mosquitoes (Diptera: Culicidae). To date, our current countrywide knowledge on the host-seeking behaviour of Iranian mosquitoes is mainly confined to host preference which has exclusively come from field studies. Olfactometer is a scientific tool by which more naive aspects of man-vector contact can be clarified under controlled and less biased conditions. Methods: The wind tunnel and stimulus delivery system was constructed from acrylic materials based on previously introduced models with some modifications. Air supply and required light were ensured by a powerful compressor and incandescent bulbs, respectively. Desired level of temperature was maintained by controllable heating radiators. For humidity production a unique in-built piezo system was devised in the course of the air flow. Fine regulators facilitated the continuous generatation of the humidity at a preset level. Results: Titanium tetrachloride smoke plus monitoring of the wind speed revealed that the flow of air was proper and invariable. A desired level of humidity and temperature could be set up in just 10 and 15–45 min, respectively. These physical parameters varied only ±2% (humidity) and ±0.15ºC (temperature) in a typical 20 min duration. Conclusion: The first sophisticated olfactometer in the field of medical entomology in Iran is reported here. Fast set up and stability of physical parameters are its salient features. It is expected that with the aid of this olfactometer further information on the physiological principles of the host-seeking behaviour of mosquitoes become available soon.