Hamid Reza Basseri

Background: The German cockroach (Blattella germanica) is a pest with a global distribution that has adapted to live in human environments. Blattella germanica threatens human health by producing asthma-inducing allergens, carrying pathogenic/antibiotic-resistant microbes, and contributing to unhealthy indoor environments. Effective application of insecticides can play an important role in cockroach control programs. The purpose of this research was to develop and optimize a nanoparticle-based imidacloprid insecticide and evaluate its effectiveness against the German cockroach. Methods: A bioassay was conducted to determine the LC50 and LC90 of imidacloprid technical against adult German cockroaches. The appropriate initial concentration of 3mg/m2 was then utilized in the synthesis of nanoencapsulated imidacloprid via the ionic gelation method. The average particle size was determined using Dynamic Light Scattering (DLS) and the dried nanoparticles were analyzed using a Scanning Electron Microscope (SEM). The LC50 and LC90 values of Nano-imidacloprid were then compared with the technical grade of the insecticide. Results: A comparison of the bioassay results for nanoencapsulated and imidacloprid technical revealed a superior in­secticidal effect of the nanoencapsulated imidacloprid against the German cockroach. The LC50 value for the nanoen­capsulated imidacloprid decreased from 4.656 to 3.081 mg/m2 and the LC90 value decreased from 8.381 to 4.486 mg/m2 when compared to imidacloprid technical. Conclusion: The use of nanotechnology in insecticides can lead to increased efficacy and reduced consumption. This is because the smaller particle size of nanomaterials allows for better penetration and targeted delivery to pest organisms, reducing the overall amount needed for control.

Background: High frequency of insecticide used to control German cockroaches may lead to insecticide resistance development. We aimed to compare the level of insecticide resistance and heterogeneity in insecticide resistance of field-collected German cockroaches in eight selected zones of Mashhad City, Razavi Khorasan Province, Iran. Methods: The present study was conducted from October 2019 to May 2021. Adult and nymphs of German cockroaches were collected from infested restaurants or hotels in eight zones of Mashhad City and then colonized in an insectarium. The cockroaches were subjected to bioassay against cypermethrin insecticide. In addition, the genomic DNA of each cockroach population was analyzed in the region where the kdr mutations reside in the German cockroach. Results: The LT50 values against cypermethrin in the susceptible strain (SS) and eight field-collected strains so varied from 17.52 to 95.36 min. The resistance ratio of the strains was also different in response to the insecticide. The similarity of multiple sequence alignments at the amino acid level was 97.5%-100%. An exon 20 transversion mutation and a nonsynonymous substitution were found. The L1014F substitution was detected in 83.4% of the cockroach samples. Conclusion: The field-collected strains were resistant to cypermethrin at different levels. Furthermore, the molecular study confirms the heterogeneity in the level of resistance among eight strains. Therefore, eight strains might have a different history of insecticide treatment.

Background: West Nile virus (WNV) is a mosquito-borne virus that causes a febrile disease and may cause a fatal neurological illness in humans. We aimed to investigate the geographic distribution of Culicinae mosquitoes and their possible infection with WNV in Hormozgan Province, southern Iran. Methods: Field studies were carried out from June 2017 to May 2019. Different mosquito sampling methods were used monthly to collect mosquitoes from 22 sites. The Real-Time PCR technique was used to detect the virus infection in the mosquitoes. Results: Overall, 6165 mosquitoes were caught. The species were Culex theileri (33.25%), Cx. pipiens (20.45%), Cx. quinquefasciatus (10.51%), Aedes caspius (6.33%), Cx. tritaeniorhynchus (5.82%), Ae. vexans (4.10%), Cx. sinaiticus (3.62%), Cx. antennatus (3.29%), Culiseta longiareolata (2.81%), Cx. perexiguus (2.03%), Cs. subochrea (1.95%), Cx. mimeticus (1.49%), Cx. pusillus (1.38%), Cx. univittatus (1.27%), Cx. modestus (1.14%), and Cx. sitiens (0.57%). The molecular detection of virus infection in mosquitoes found to be negative for WNV. Conclusion: The presence of many species of mosquito vectors and high population traffic increase the risk of disease transmission is very high. Therefore, the way to restrict WNV infection factors is increasing the knowledge for personal protection measures to prevent mosquito bites.

The Article Abstract is not available.

Background: Due to undesired environmental impact of insecticides as well as resistant of vectors to them, the development of organic and natural insecticides has been more considered. In the current study, we developed nanoemulsion of eucalyptus and investigated lavicidal activity of it against malaria vector, Anopheles stephensi and Culex pipiens under laboratory as well as semi-field conditions. Methods: An optimized nanoemulsion was prepared by mixing Eucalyptus oil, Tween 80 and ethanol at ratio of 1:2:1.5 in distilled water, then, stirred for 20 minutes at room temperature. The product was then used for bioassay tests against 3-4th instar larvae of Anopheles stephensi as well as Culex pipiens. Furthermore, a semi-field trial was carried out to evaluate larvicidal activity of nanoemulsion of eucalyptus. Results: Nanoemulsion of eucalyptus showed significantly high lavicidal activity comparing with bulk eucalyptus essential oil. The LC50 and LC90 value of nanoemulsion against An. stephensi were 111.0 and 180.8 ppm respectively and 29.5 and 73.7 ppm for Cx. pipiens, respectively. In the semi field condition, the Nanoemulsion of eucalyptus decreased 1-2nd instar larval density of Culicines and Anophelines to 90.1% and 85.2%, respectively. Conclusions: The nano formulation of eucalyptus oil showed high larvicidal activity. Therefore, nanoemulsion of eucalyptus oil can be used as an eco-friendly larvicide against mosquitoes.

Background: Cytochrome P450-dependent monooxygenases are a very important metabolic system involve in insecti­cide resistance. This study was conducted to find the association between the expression level of cytochrome P450 (CYP450) and permethrin-resistance level among four strains of the German cockroach Blattella germanica (L) (Blat­todea: Ectobiidae). Methods: Three field strains of German cockroach with different frequency of exposure to pesticides, and a laboratory susceptible strain were used in the present study. Insecticide susceptibility bioassays were carried out to detect re­sistance to permethrin. The concentration of CYP450 in each strain was determined using ion-exchange HPLC chroma­tography. Biochemical assays was performed to analyse CYP450 activities. Results: The resistance ratios (RR) to permethrin among three field strains were 3.29, 4.10 and 6.17-fold comping with the susceptible stain. The CYP450 activity of three field strains was 1.6, 2.4 and 2.7 times higher than in the sus­ceptible stain. The amount of CYP450 per mg of protein was significantly different between the susceptible and the three re­sistant strains. The resistant cockroaches showed a relatively high expression of CYP450 enzymes. A strong corre­la­tion was found between permethrin resistance level and total concentration of CYP450 enzymes. Conclusion: The results of current study show that more frequent usage of a pyrethroid insecticide cause the metabolic insecticide resistance to rise in German cockroach. Therefore, there is a ratio correlation between resistance level and monooxygenases activities in insect. Thus, the control program must be managed according to history of pesticide us­age.

Background: Mosquito species are highly considering as disease transmission as well as nuisance insects. One of the principal strategy to protect human from the mosquito bites is repellent agents. This study aimed to assess repellency of two organic essential oils, Eucalyptus globulus and Syzygium aromaticum from bites of malaria vector, Anopheles stephensi. Methods: The study was conducted in 2019-2020. The components of essential oils of E. globulus and S. aromaticum was determined using gas chromatography/mass spectrometry. The unfed female mosquitoes aged 2-5 d old were used in all experiments. In vivo Klun and Debboun module bioassays were utilized on human-volunteer skin. The essential oils at serial concentrations were used to find repellent efficacy against Anopheles landings and bites. To find the synergistic effect, four combinations of the essential oils were tested. Results: The main composition of E. globulus essential oil was 1,8-Cineol (78.20%), whereas that of S. aromaticum essential oil was 2-methoxy-3-(2-propenyl) (77.04%). Based on minimum effective dose (≤1% biting), 10% (v/v) of E. globulus showed high landing repellency (77.78%), whereas minimum effective dose of S. aromaticum at concentration of 1% had high landing repellency (88.89%). Among four combinations, the ratio of 1:1 of E. globulus (10%):S. aromaticum (1%) showed the most landing repellency (94.44%). Conclusion: The combinations of two essential oils had the most potential repellency effect against landing of mosquitoes. As essential oils are eco-friendly with less irritation for human skin, E. globulus and S. aromaticum essential oils are recommended as effective and safe mosquito repellents.

Background The aim of current study was to determine the protection efficacy of Eucalyptus globulus and Syzygium aromaticum essential oils nanoemulsions-loaded textiles versus bulk essential oil- treated textiles against the malaria vector, Anopheles stephensi. Methods The components of E. globulus and S. aromaticum essential oils were determined using gas chromatography/mass spectrometry. Then, the nanoemulsions of both essential oils were prepared using a low energy emulsification method. Their stability and droplet sizes were determined, and the repellent efficacy against landings/bites of the starve mosquito females was examined using textile panels of polyester/cotton, impregnated with serial concentrations of the nano-emulsion. Results The main compositions of E. globulus essential oil were 1, 8-cineol (64.58%) and alpha-pinene (10.63%), whereas those of S. aromaticum essential oil were 2-methoxy-3-(2-propenyl) (77.04%) and trans-caryophyllene (11.99%). Transparent oil in water nanoemulsion system consisting of essential oils, Tween-20, Tween-80 and propylene glycol was developed. The median droplet size was 11.2-23.1nm depending on dilution ratio. Protection time of nanoemulsion-loaded textile (285 ± 30 min) was noticeably higher than that of bulk essential oils (< 5 min). Conclusions It was concluded that nanoemulsion of essential oils may be interesting options in control of mosquito-related diseases.

The article's abstract is no available.

Background: Lectin molecules have crucial biological role in insects’ immune system. The aim of present study was to find the agglutinin activities in haemolymph of German cockroach, Belatella germanica with appropriate screening and purification. Methods: The heamolymph of cockroach was collected and agglutinin test performed against different animal and human red blood cells (RBC). Then sugar inhibition assay was carried out to find carbohydrate specific binding lectin. The proteins of haemolymph was purified using ion-exchange chromatography (HPLC) and each fraction was tested for agglutinin activity. Finally the molecular weight of the agglutinin protein was determined using SDS-page. Results: The most agglutinin activity of haemolymph was found against RBC of mouse at titer 1/128ml/L dilution and sugar inhibition assay showed that fucos, N-acetyglucoseamine and galactose reduced titer of agglutinin to ½ml/L. Only one fraction of heamolymph at rotation time of 36 minute showed agglutinin activity. The molecular weight of this lectin was measured as 120Kds. Conclusion: The range of agglutinin activities against different RBC indicates that the isolated lectin is not specific for a particular carbohydrate. In addition, the isolated lectin at low concentration present in heamolymph should be an innate lactin not secreted, because we found it without any trigger immunity of the insect.