Journal of Arthropod-Borne Diseases
Volume:6 Issue: 2, Dec 2012

The efficacy of essential oil of Chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against Blattella germanica male adults. Composition of essential oil was determined by GC-MS. Topical application bioassay was used to evalu­ate contact toxicity of essential oil and three main components. Fumigant toxicity of essential oil and its main com­ponents was measured using a sealed space method. Twenty-two components were identified in the essential oil and the main components were (Z)-ascaridole (29.7%), isoascaridole (13.0%), ρ-cymene (12.7%) and piperitone (5.0%). The essential oil and (Z)-ascaridole, isoascaridole and r-cymene possessed fumigant toxicity against male German cockroaches with LC50 values of 4.13, 0.55, 2.07 and 6.92 mg/L air, respectively. Topical application bioassay showed that all the three compounds were toxic to male German cockroaches and (Z)-ascaridole was the strongest with a LD50 value of 22.02 mg/adult while the crude oil with a LD50 value of 67.46 mg/adult. The essential oil from Chinese C. ambrosioides and its three main active ingredients may be explored as natural potential insecticides in the control of cockroaches.

The present study was undertaken to compare the entomological situation by analyzing the blood meal of mosquitoes of canal irrigated and non-irrigated areas of Bikaner in order to explore scientific information on the vector biology and malaria burden profile and to plan proper strategies for malaria control and eradication. Adult mosquitoes were collected and the abdomen of the blood fed females were crushed on a filter paper for blood meal analysis and subjected to precipitin test. The blood meal analysis showed that Anopheles subpictus had a preference towards cattle blood, An. culicifacies and An. stephensi preferred human blood, while, An. annularis was noted to feed only on bovine blood. Although An. annularis, has been recently reported from the area, was found to feed exclusively on bovine blood, earlier reports suggest that this species is a vector of malaria and therefore preventive measures should be taken well in advance before this species gets established in the area.

Development of insecticide resistance occurred due to the continuous and misuse of synthetic insecti­cides therefore, the recent study was conducted to explore eco-friendly plant extracts that have some potential to sup­press mosquito larval population. World Health Organization recommended mosquito larval bioassay method for insecticide was used while for the analysis of citrus oils for limonin and nomilin content HPLC was used. Among the two citrus cultivars tested as larvicide against Aedes albopictus, valencia late (Citrus sinensis) was the best in terms of LC50 (297 ppm), % mortality (97%) and LT50 (18.49 hours) then freutrall early (Citrus reticulate) with LC50 (377.4 ppm), % mortality (88%) and LT50 (31 hours), While nomilin gave lowest LC­­50 (121.04 ppm) than limonin (382.22 ppm) after 72 hours of exposure. Valencia late also had more limonin and nomilin (377 µg/ml and 21.19 µg/ml) than freutrall early (5.29 µg/ml and 3.89 µg/ml) respectively. Valencia late showed best results in term of LC50, LT50 and percentage mortality against Aedes albopictus as it has more amount of nomilin then freutrall early, however further evaluation in the field conditions is required.

The German cockroach, Blattella germanica is a major hygienic pest and mechanical vector for path­ogenic agents in hospitals and residential areas. The development of insecticide resistance is a serious problem in controlling of this pest. Toxicity of four commonly used insecticides (permethrin, cypermethrin, malathion and chlorpyrifos) against two hospital- collected strains of the German cockroach was investigated. Topical bioassay methods were carried out for detecting insecticide susceptibility of adult male cock­roaches. For each insecticide, four to six concentrations resulting in >0% and <100% mortality were used. Three to six replicates of 10 cockroaches per concentration were conducted. The differences between LD50 (µg/g) values were considered statistically significant only when the 95% confidence intervals did not overlap. Two hospital- collected strains of the German cockroach showed low to moderate levels of resistance to chlorpyrifos, permethrin, malathion and cypermethrin based on resistance ratios compared with susceptible strain. The low level chlorpyrifos resistance suggesting this insecticide may still provide adequate control of these strains. While the obsereved moderate levels of resistance to cypermethrin could imply developing resistance to this compound.

Bait-trapping appears to be a generally useful method of studying fly populations. The aim of this study was to construct a new adult flytrap by some modifications in former versions and to evaluate its applicability in a subtropical zone in southern Iran. The traps were constructed with modification by adding some equipment to a polyethylene container (18× 20× 33 cm) with lid. The fresh sheep meat was used as bait. Totally 27 adult modified traps were made and tested for their efficacies to attract adult flies. The experiment was carried out in a range of different topographic areas of Fars Province during June 2010. The traps were able to attract various groups of adult flies belonging to families of: Calliphoridae, Sarcophagidae, Muscidae, and Faniidae. The species of Calliphora vicina (Diptera: Calliphoridae), Sarcophaga argyrostoma (Diptera: Sarcophagidae) and Musca domestica (Diptera: Muscidae) include the majority of the flies collected by this sheep-meat baited trap. This adult flytrap can be recommended for routine field sampling to study diversity and population dynamics of flies where conducting of daily collection is difficult.

The present study aimed to demonstrate the seasonal activities of Ixodes ricinus at the pasture level and on the host. A vast pasture in Amol countryside (Mazandaran Province, Iran) which had the potential for a considera­ble number of cattle and sheep to graze was chosen. Tick sampling from the skin of 130 cattle and 130 sheep were collected every month interval. Simultaneously, the activity of the different stages of I. ricinus on the pasture was considered by dragging method. The collected ticks were placed in jars containing 70% alcohol and sent to the para­sitological laboratory for identification. The rate of the infestation with adult I. ricinus in cattle and sheep increases gradually with the beginning of fall and reaches its peak in January, February and March while it starts to decline with the beginning of spring as the infestation rate reach to zero in summer months. Accordingly, the highest number of adult I. ricinus existed on the cattle during January, February, and March. In addition, the results of dragging have been revealed that the active tick population in the pasture exists during November, December, January, and March. Ixodes ricinus is regarded a common tick species in Amol (Mazandaran). Due to the biological properties of I. ricinus which is active in the cold and humid months of the year, the prevalence of ruminant infestations with I. ricinus in this area increases from November to March but reaches to zero again with the beginning of summer.

Diabetes is an important disease. This disease is a metabolic disorder characterized by hyperglycemia resulting from perturbation in insulin secretion, insulin action or both. Honey bee venom contains a wide range of polypeptide agents. The principle components of bee venom are mellitin and phospholipase A2. These components increase insulin secretion from the β-cells of pancreas. This study was conducted to show the hypoglycemic effect of honey bee venom on alloxan induced diabetic male rats. Eighteen adult male rats weighting 200±20 g were placed into 3 randomly groups: control, alloxan monohy­drate-induced diabetic rat and treated group that received honey bee venom daily before their nutrition for four months. Forty eight hours after the last injection, blood was collected from their heart, serum was dissented and blood glucose, insulin, triglyceride and total cholesterol were determined. Glucose serum, triglyceride and total cholesterol level in treated group in comparison with diabetic group was significantly decreased (P< 0.01). On the other hand, using bee venom causes increase in insulin serum in com­parison with diabetic group (P< 0.05). Honeybee venom (apitoxin) can be used as therapeutic option to lower blood glucose and lipids in dia­betic rats.

Anopheles fluviatilis, one of the major malaria vectors in Iran, is assumed to be a complex of sibling species. The aim of this study was to evaluate Cytochrome oxidase I (COI) gene alongside 28S-D3 as a diagnostic tool for identification of An. fluviatilis sibling species in Iran. DNA sample belonging to 24 An. fluviatilis mosquitoes from different geographical areas in south and southeastern Iran were used for amplification of COI gene followed by sequencing. The 474–475 bp COI sequences obtained in this study were aligned with 59 similar sequences of An. fluviatilis and a sequence of Anopheles minimus, as out group, from GenBank database. The distances between group and individual sequences were calculated and phy­logenetic tree for obtained sequences was generated by using Kimura two parameter (K2P) model of neighbor-join­ing method. Phylogenetic analysis using COI gene grouped members of Fars Province (central Iran) in two distinct clades separate from other Iranian members representing Hormozgan, Kerman, and Sistan va Baluchestan Provinces. The mean distance between Iranian and Indian individuals was 1.66%, whereas the value between Fars Province individ­uals and the group comprising individuals from other areas of Iran was 2.06%. Presence of 2.06% mean distance between individuals from Fars Province and those from other areas of Iran is indicative of at least two sibling species in An. fluviatilis mosquitoes of Iran. This finding confirms earlier results based on RAPD-PCR and 28S-D3 analysis.

West Nile Virus (WNV) is a mosquito-borne disease that can cause fatal infection in mammals in­cluding humans, dogs, horses, birds and reptiles. Although West Nile Virus is an asymptomatic infection, especially it can cause neurologic disorders in humans and horses. The aim of this study was to the investigate virological pres­ence of WNV in horses in the Black Sea Region of Turkey using real time RT-PCR (rRT-PCR). Totally, 120 horse sera were collected equally from 4 provinces in Middle Black Sea Region of Turkey and investigated for WNV presence by Taqman based rRT-PCR. WNV nucleic acid was not detected in any horse serum sample. Although obtained result indicated no evidence of WNV–RNA in horses, Black Sea Region of Turkey is one of the suitable places for the WNV infection. For this reason, our research will continue for the determination of the viruses in vectors and susceptible animals such as horses, dogs, etc.

Myiasis, the invasion of live human tissue by larva of Diptera, is reported in the nasal cavity of a 5.5-year-old Iranian girl. She was referred from Golestan Province to the Shaheed Rajaei Heart Center in Tehran. In the 41th day after admission, a live parasite was found in her nasal secretions suction identified presumably as a second instar larvae of a facultative myiasis, Woholfartia nuba (Diptera: Sarcophagidae), on the basis of mtDNA-COI and morphological characteristics. Since presence of the larva was recorded after hospitalization, by definition, this infestation is considered a nosocomial myiasis.