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Anopheles stephensiis an efficient vector of malaria parasites in Iran. Despite its importance in malaria transmission, there is a scarcity of accurate predictive models of its rates of development at different temperatures. A laboratory colony of An. stephensi,collected from Bandar Abbas County, southern Iran, was established, and all its developmental stages were maintained in temperature-controlled incubators so that the water temperature set at 5, 8, 10, 12.5, 14, 28, 38, 39.5, 42, and 45(±0.2) °C for different treatments until subsequent adult emergence. The Lower and Upper Developmental Temperatures (LDT and UDT) and the growth degree-day (GDD) were calculated for each development stage. A 12-mo population dynamics survey of the larvae and adults of An. stephensiwas performed in 3 malaria-endemic villages (Geno, Hormoodar, and Sarkhoon) of Bandar Abbas County, and the obtained data were matched with the constructed GDD model. Based on the field meteorological and dynamics data, the model was verified in the field and used to determine the appropriate date to start spraying. The LDT was determined to be 8.19, 9.74, 8.42, 5.6, 13.57, and 10.03 °C for egg hatching, first, second, and third ecdysis, pupation, and eclosion events, respectively. The UDT was 38 °C for all developmental stages. The thermal requirement for the development of all immature stages of An stephensiwas determined to be 187.7 (±56.3) GDD above the LDT. Therefore, the appropriate date to start residual spraying is when the region’s GDD reaches 187.7 (±56.3). Given the climatic conditions in Bandar Abbas County, it is expected that the first activity peak of adult An. stephensiwould be in March. Field observations showed that An. stephensiactivity starts in February and peaks in March. The GDD model can provide a good estimate for peak An. stephensiactivity and indicate the optimal deployment time of residual spraying operations against the multiplication and development of malaria parasites inside the vector.

The aim of the present study was to explore resistance markers and possible biochemical resistance mechanisms in the Phlebotomine sand fly Phlebotomus papatasiin Esfahan Province, central Iran. Homogenous resistant strains of sand flies were obtained by exposing P. papatasicollected from Esfahan to a single diagnostic dose of DDT. The adults from the colony were tested with papers impregnated with four pyrethroid insecticides: Permethrin 0.75%, Deltamethrin 0.05%, Cyfluthrin 0.15%, and Lambdacyhalothrin 0.05% to determine levels of cross-resistance. To discover the presence of mutations, a 440 base pair fragment of the voltage gated sodium channel (VGSC) gene was amplified and sequenced in both directions for the susceptible and resistant colonies. We also assayed the amount of four enzymes that play a key role in insecticide detoxification in the resistant colonies. A resistance ratio (RR) of 2.52 folds was achieved during the selection of resistant strains. Sequence analysis revealed no knockdown resistance (kdr) mutations in the VGSCgene. Enzyme activity ratio of the resistant candidate and susceptible colonies were calculated for α-esterases (3.78), β-esterases (3.72), mixed function oxidases (MFO) (3.21), and glutathione-S-transferases (GST) (1.59). No cross-resistance to the four pyrethroids insecticides was observed in the DDT resistant colony. The absence of kdrmutations in the VGSCgene suggests that alterations in esterase and MFO enzymes are responsible for the resistant of P. papatasito DDT in central Iran. This information could have significant predictive utility in managing insecticide resistant in this Leishmaniavector.

Although malaria is endemic in some areas of southeastern Iran, following the successful national malaria elimination plan, the local transmission area has been shrunk. The main cases in Iran are due to Plasmodium vivaxfollowed by P. falciparum. This study was aimed to determine the current situation of malaria in Kerman Province of Iran and evaluate the insecticide resistance of main vectors. The field study was conducted in 2019. Data of new malaria cases were obtained from the health centers for the period of 2009–2018. Susceptibility status of Anopheles stephensiand An. dthaliwas evaluated against dichlorodiphenyltrichloroethane, Dieldrin, Malathion, Bendiocarb, Deltamethrin, and Temephos at the diagnostic dose. A total of 522 malaria cases were recorded and divided into indigenous (33.14%) and imported (66.86%) categories. The highest incidence of the disease was reported from the southern areas of the province, where all indigenous cases occurred. Adults of An. stephensiwere resistant to dichlorodiphenyltrichloroethane while its resistance to be confirmed to dieldrin, bendiocarb and deltamethrin. As An. dthalihad less than 98% mortality against bendiocarb, the resistance status should be confirmed with more tests. Our findings showed both species had less than 98% mortality against bendiocarb and deltamethrin insecticides which are used in malaria vector control program in Iran. Due to the susceptibility of these vectors to temephos, larviciding can be advised for vector control in this area.

Malaria is the most important mosquito-borne disease, which is transmitted by Anopheles species. According to the recent report of World Health Organization, there were an estimated 229 million malaria cases in 2019 in 87 malaria endemic countries. There are several vector control method specially using pesticides. The aim of this study was to collect all the data about insecticide resistant of malaria vectors in the Eastern Mediterranean region countries. In this study, all the published papers related to insecticide resistance of malaria vectors in the region were collected and resistant status of vectors in the countries was mapped. Resistance to different insecticide classes such as pyrethroids, organophosphate, organochlorine and carbamates were evaluated using World Health Organization guidelines. Results showed a wide variety of susceptibility/resistance status to these chemicals according to the location, historical context of pesticide used, genetic background of vectors, age and abdominal conditions of adults may play a role in the susceptibility status of these species to different insecticides. The results of this study is providing a guideline for countries to manage their vector control activities against insecticide resistance of malaria vectors and provide novel approaches such as male sterility, using Wolbachia, using new insecticide with new mode of action.Graphical Abstract

Malaria and leishmaniasis are the public health problems in southern Iran. The main activity of vector control is indoor residual spraying using pyrethroids, using different insecticides as larviciding and impregnated bednets. The aim of study was to evaluate the biological assays of bendiocarb wettable powder (WP) at different surfaces of wall. The residual effect of bendiocarb WP80 at 400 milligram/meter square (mg/m2) was evaluated on various local surfaces of rooms such as mud and plaster as well as thatch roofs and wooden. World Health Organization standard cones using contact bioassays were carried out using laboratory reared sugar-fed, 48-72 h old females of Anopheles stephensi. Contact bioassays were carried out on sprayed surfaces for 150 days. Contact bioassay on surfaces treated with bendiocarb WP80 at different surfaces was estimated about 2 months. Fumigant tests of bendiocarb WP80 at 400 mg/m2revealed 50-93.83% mortality with 1 month persistency. The results showed that carbamate insecticide could be used as rotation with pyrethroids for malaria vector control. Monitoring and evaluation of environmental toxicology of pesticides is important for decision making for choosing appropriate pesticides for disease vector control.

Climate change is an important factor affecting the dynamics of the vectors population and, hence, the risk of vector-borne diseases. This study aimed to predict the environmental suitability for malaria vectors in Iran under climate change scenarios in 2030s and 2050s. Literature search was performed to find documents on the spatial distribution of Anopheles stephensi Liston, 1901, Anopheles culicifaciess.l. Giles, 1901, Anopheles fluviatiliss.l. James, 1902, Anopheles superpictuss.l. Grassi, 1899, Anopheles dthali Patton, 1905, Anopheles maculipenniss.l. Meigen, 1818, and Anopheles sacharoviFavre, 1903 (Diptera: Culicidae) published between 1970 and 2017. The bioclimatic data under three climate change scenarios (representative concentration pathway 2.6 [RCP2.6], RCP4.5, and RCP8.5) and MaxEnt model were used to predict the ecological niches for each species. Comparison between the two study periods under the three scenarios for each species revealed that RCP8.5 would reduce the area at risk for An. culicifaciess.l., An. dthaliand An. superpictuss.l. in the 2050s compared to the 2030s, but the reverse will be induced by RCP2.6 and RCP4.5 scenarios. For An. fluviatiliss.l., RCP2.6 will reduce the risk areas in the 2050s, whereas an increase is expected under the two other scenarios. Moreover, all scenarios would decrease the high-risk areas of An. maculipenniss.l. in the 2050s. For An. sacharovi, RCP2.6 would increase its high-risk areas, whereas RCP4.5 and RCP8.5 would decrease its exposure. The high-risk area of An. stephensiis expected to increase under RCP8.5 in the 2030s and RCP4.5 in 2050s, but it will be almost unchanged or reduced under other scenarios.

The mosquito Culex pipiensis the primary vector of Rift Valley fever, West Nile, encephalitis, and Zika viruses, and periodic lymphatic filariasis. Developing insecticide resistance in mosquitoes demands the development of new approaches to fight these diseases. Paratransgenesis and RNAi approaches by using engineered bacteria have been shown to reduce mosquito vector competence. Serratia-AS1 is a bacterium found in mosquitoes and was genetically modified for expression of antimalaria effector molecules that repress development of malaria parasites in mosquitoes. The aim of this study was to determine how a genetically marked Serratiastrain expressing the mCherry fluorescent protein (mCherry-Serratia) affects the colonization potential, life span, blood feeding behavior, fecundity, and fertility of Cx. pipiens. mCherry-Serratiabacteria disseminated into larvae, pupae, and newly emerged adults and dramatically increased in numbers following a blood meal. The bacterium was transmitted to progeny, showing that it can extend horizontally, transstadially, and vertically through the mosquito population. The presence of mCherry-Serratiadid not affect blood feeding behavior, survival rate, fecundity, and fertility of Culexmosquitoes. This is the first study to evaluate the effects of an engineered bacteria on the fitness of Cx. pipiens. Although challenges remain, such as producing engineered bacteria to secrete anti-pathogens associated with Cx. pipiens, introducing such bacteria into mosquito populations, our findings of minimal fitness cost caused by Serratia-AS1 bode well for the development of paratransgenesis and RNAi approaches.

AbstractSand flies of Phlebotomus papatasiand P. sergentiare the main vectors of cutaneous leishmanisis (CL) in the old world. We aimed to screen Iranian P. papatasiand P. sergentifor their natural infections with Wolbachiaand to determine their phylogenetic association with other species. Wolbachiasurface protein (wsp) gene was PCR amplified from DNA extracted from Phlebotomusspecies, sequenced, and were analysed in combination with wspsequences related to Phelebtominae and other insects. All Wolbachia-infecting Iranian sand flies of P. papatasiand P. sergentiwere classified in the Supergroup A., Wolbachiaisolated from P. sergentiwere clustered in a new subgroup within Supergroup A so-called wSreg. The Wolbachiastrains identified from the P. papatasiclustered mainly in the subgroup wPap and partly in wSerg. Multiple Wholbachiainfection within a single population of P.papatasiwarrants investigation on existence and intensity of cytoplasmic incompatibility between the wPap and wSerg subgroups.

AbstractIn the current study, the effects of the presence of symbiotic bacteria on the activity of the enzymes involved in An. stephensiresistance to temephos are evaluated for the first time. Four different strains (I. susceptible strain, II. resistant strain, III. resistant strain + antibiotic, and IV. resistant strain + bacteria) were considered in order to determine the possible effects of the symbiotic bacteria on their hosts’ resistance to temephos. The median values of all enzymes of susceptible strain were compared with those of other resistant strains. The results of this study indicated a direct relationship between the presence of bacteria in the symbiotic organs of An. stephensiand resistance to temephos. The profile of enzymatic activities in the resistant strain changed to a susceptible status after adding antibiotic. The resistance of An. stephensito temephos could be completely broken artificially by removing their bacterial symbionts in a resistant population.

AbstractMosquitoes are responsible for the transmission of many pathogens and parasites, which cause serious diseases in humans. Currently, applications of plant derivatives have been suggested as alternative bio-control technique for these medically important vectors and pests. Laboratory bioassay of the seed essential oil extracted from an indigenous plant, Bunium persicumwas carried out against the larvae of two vector species of mosquitoes in order to evaluate its mosquito larvicidal effect. In addition, Chemical composition of the essential oil was analyzed using gas chromatography-mass spectrometry (GC-MS). Thirty-five constituents were identified, the main constituents of the oil were p-cuminaldehyde (23.50%), α-methyl-benzenemethanol (14.59%), γ-terpinene (13.10%) and β-cymene (8.48%). Five concentrations of essential oil were evaluated against the 4th instar larvae of Anopheles stephensiand Culex pipiens. The LC50and LC90values against An. stephensilarvae were 27.72 and 91.35 ppm and for Cx. pipienswere 20.61 and 52.31 ppm, respectively. Our finding suggests that B. persicumoil has potential source of valuable larvicidal compounds for mosquito larval control.