The useful mosquito trap was to be effective, non-toxic, and covers a wide area. The present investigation revealed that the attraction pattern of four anophelinae, two culicinae, and one aedeniae mosquitoes was varied and also highly depended on the type of the traps.
Anopheles stephensi is the main malaria vector in Iran, and three biological forms i.e. type, mysorensis, and intermediate of the species have been reported in the Hormozgan Province [30]. This study demonstrated that the cow urine-baited resting traps have been more attractive to An. stephensi than either odor-baited boxes or other methods. This observation was consistent with that of Kweka et al [23, 31], who reported a higher density of An.arabiensis in CUBT followed by CBBT, and UBT respectively. The efficiency of CUBT is dependent on the place of the trap in indoors and outdoors. In our study, CUBT has a longer desirable effect on An. stephensi, which tend to rest inside the houses and shelter. On the other hand, the proportion of gravid and semi gravid of An. stephensi species collected by CUBT was lower than that of unfed and blood-fed ones. It seems that this species blood meal on both humans and cows rests in shelters to complete their gonotrophic cycle. Despite the widespread distribution of LLINs and ITNs among residents in southern Iran, most of them do not use a mosquito net when they sleep. This finding could be highlighted for programs of vector control such as IRS (indoor residual spraying), which impact on endophilic vector species as well as health promotion through the distribution of ITNs and LLINS. This finding agrees with a study performed on An stephensi in the south and southeastern Iran [32] and also control of malaria program in Africa [33].
Anopheles fluviatilis s.l. is the malaria vector in Iran and only species T has been reported from Iran [34, 35]. So far, at least three sibling species S, T, and U have been reported in the world [36]. In our study, An. fluviatilis s.l. more collected by HLC followed by APS, CUBT, CBBT, CO2- Bt, HBBT, and CBT. The ratio of semi gravid plus gravid to unfed plus fed of female An. fluviatilis s.l. was more than one indicated exophilic behavior. Agree with our finding, Basseri et al (2010) was relieved exophilic behavior with a high anthropophagic index for An. fluviatilis s.l. species [32].
An. dthali has been reported as a secondary vector for malaria in Iran [37]. In our study, An. dthali was more abundant in artificial pit shelters, followed by CUBT, CO2-Bt, HLC, CBBT, HBBT, and CBT. The abdominal condition of the female An. dthali during our study shows exophilic behavior. Agree with our finding, Basseri et al (2010) was reported the exophilic behavior of An. dthali [32].
An. culicifascies s.l. is the main malaria vector in Iran [38]. In the present study, this species was most abundant in UBT (n = 4, 57.2%) followed by HLC (n = 3, 42.8%). This species was captured by UBT, and found unfed, freshly fed, semi gravid, and gravid. Although we collected a few An. culicifascies s.l. during of this study, based on the ratio of abdominal condition was observed both endophilic and exophilic behaviors. The same result has been reported in a previous study [32]. In our study, this species was collected in the second third of the night by HLC. Agree with our study, more biting activity of this species was observed before midnight [39]. In contrast, this species was reported as the zoophilic behavior [6, 38]. We collected a few An. culicifascies s.l. during of this study, so at the present, we were unable to decide about comparable behavior.
Anopheles superpictus s.l. is one of the seven species of malaria vectors in Iran [6]. This species were captured in CBBT (n = 5, 45.4%) followed by APS (n = 6, 54.6%). Exophilic behavior of this species collected by APS was found based on the ratio of abdominal condition. The same result has been reported by Nejati et al. (2013) [6]. We collected a few An. superpictus s.l. during of this study, so at the present, we were unable to decide about comparable behavior. Anopheles superpictus s.l. is the main vector in the Central Plateau of Iran [40]. This species had the highest abundance and distribution among Anopheles in Kashan County and the best sampling method for its adults was the BG trap [41, 42].
An. pulcherrimus is a suspected malaria vector in Iran [39]. Our founding relieved the more abundant of this species in UBT (n = 2, 22.2%) followed by HLC (n = 7, 77.8%). In our study, this species was collected in the second third of the night by HLC. Agree with our study, more biting activity of this species was found to occur before midnight [39]. Also, this species was captured by UBT, and found unfed, freshly fed, semi gravid, and gravid. Although we collected a few An. pulcherrimus during this study, based on the ratio of abdominal condition was observed exophilic behaviour. Agree with our study Zaim et al (1993) was reported the exophilic behaviour of this species [38]. We collected a few An. pulcherrimus during of this study, so at the present, we were unable to decide about comparable behavior.
In our research, the use of various sampling methods to collect some culicinae sub-family and the tribe Aedini species from indoor and outdoor places helped us to know more about the behavior diversity and densities of these species.
Culex pipiens complex includes several members, more than 75 binomial names due to the complexity of synonyms [43]. Among the species complex, Culex pipiens, Cx. quinquefasciatus and Cx. pipiens form molestus are the most common members of this complex and are widespread in the world [44]. The molecular and morphological studies using ITS2, COI, Ace2 cDNA genes and DNA barcoding indicated some variations of the Culex pipiens complex in Iran [45–47]. Because of having morphological variations among the Cx. pipiens complex, sometimes it is not easy to morphologically separate from Cx. quinquefasciatus and Cx. torrentium and, need to molecular assay [47]. Recently, was reported the occurrences of Cx. pipiens pipiens biotype pipiens and a hybrid between Cx. pipiens pipiens biotype pipiens and Cx. pipiens pipiens biotype molestus in Iran [48, 49]. Culex pipiens pipiens has a wide distribution in Iran and is also reported the steno-eurygamy, anautogeny, and ornithophilic behaviors [45, 49, 50]. West Nile and Sindbis viruses are predominantly transmitted between birds [51, 52]. This species was reported a potential enzootic and bridge vectors of SINV and WNV already circulating in Iran [53, 54]. Shahossaini et al. (2018) reported the occurrence of the West Nile virus and its subtype Kunjin in Iran [49].
In our study, more Cx. pipiens collected by CBBTfollowed by CUBT and, HBBT. It seems that, this species selected calf odor over human odor, despite similar weights and thus similar CO2 expiration rates. In agreement, Shahossaini et al. (2018) reported a high proportion of birds for Cx. pipiens pipiens f. pipiens of detected blood meal sources [49]. Similarly, Culicidae species are more oriented to mosquito Magnet traps treated with synthetic mixture than MM-X traps baited only with human odors in the field [55]. In contrast, more attraction of Cx. quinquefasciatus to human skin odors were reported [56]. This finding agrees with previous studies, which indicated the Cx. pipiens has a wide range of hosts, whereas Culex quinquefasciatus more attract to selected human odor over calf odor [57–62].
Culex theileri is widespread in Iran and, was reported naturally infected with Dirofilaria immitis and Setaria labiatopapillosa [63, 64]. In our study, Cx. theileri was most collected in APS followed by CUBT, HLC and, least in CBBT. This species was not collected during the present investigation utilizing HBBT, CO2-BT and UBT. This finding agrees with previous studies in Guilan Province, northern Iran, which indicated that this dominant species was more collected from cow shelter than human shelter using CDC light trap and Hand catch methods [65]. Shahossaini et al (2018) reported a relatively high proportion of non-human mammals for Cx. theileri of detected blood meal sources [49]. Prior studies carried out in Isfahan province, central Iran, was found that, Cx. theileri as the dominant species in both larval and adult collections with exophilic and exophagic behaviour [41, 42, 66, 67]. In Kashan County, Cx. theileri and Cx. pipiens were the only species collected using the animal-baited bed net trap [41]. In contrast, we found low abundance among culicinae species. Hormozgan has a warmer climate than Isfahan province, and perhaps may explain these unexpected results, moreover there are widespread rice fields in Isfahan, so that we cannot observe them in Hormozgan. On the other hand, a lesser abundance of this species in our study, is perhaps due to the sampling method and time of collection.
Among the species collected, Ae. caspius is widespread in Iran and, known to vector WNV in northwestern Iran [68]. In our research, Aedes caspius was most abundant in the human landing catch followed by CUBT, CBBT, and HBBT. Agree with our finding, a study performed by Nejati et al (2020) reported this species was most abundant in Malayse trap and CO2-baited trap than BG and RBs [62]. Also, in agreement, Brown et al (2018) relieved that Ae. albopictus most was collected by CDC backpack aspiration, then Sticky resting bucket and, Resting bucket [69]. We observed no evidence of the occurrences of Ae. aegypti and Ae. albopictus, the important vectors of arboviral diseases in Hormozgan Province. Aedes caspius was found only Aedini species, which were collected in our study. In contrast, Hassandoost et al (2020), reported two species, Ae. caspius and Ae. vexans by larval collection in Hormozgan Province [70]. It should be considered, adult sampling methods in our study, may explain the variation in the results.
The human landing catch was introduced as the standard method for measuring human exposure to mosquito bites. However, this method potentially exposes individuals to a range of nuisance mosquitoes as well as mosquito-borne diseases and created bias through the sampling. On the other hand, baited resting boxes were not a suitable alternative method to collect of this species, which are more important in addressing entomological surveillance due to arbovirus transmission.
The artificial pit shelter was found more efficient than the baited resting boxes in the density and diversity of An. fluviatilis s.l., An. dthali, Cx. pipiens, Cx. theileri and Ae. caspius species.
In agreement, Pombi et al. (2014) reported the low abundance of Afrotropical malaria vectors by Sticky resting box (SRB) than the pit-shelters [71]. Also, our finding agrees with a study performed on An. arabiensis, and An. funestus s.l. in south-eastern Tanzania [72], which the mean abundance of these species collected with SRB traps inside and outdoors was significantly lower than with Back Pack Aspiration and Resting Bucket traps. Overall, very low numbers of mosquitoes were capture from the RBs baited with human odour [73], an observation similar to what was found in the current study.
The proportion of gravid and semi gravid to unfed and blood-fed showed the exophilic behavior of these species. The higher density of semi-gravid and gravid mosquitoes using the APS method is useful in evaluating the oviposition behavior of malaria vectors and in determining the best control method in targeting ovipositing mosquitoes. This finding could be highlighted for programs of vector control such as larviciding and thermal fogging, which impact exophilic mosquito species.
Our finding indicated that, the case of black un-baited resting boxes was the priority for all species. Agree with our finding, Burkett et al. (1998) showing Aedes aegypti preferred black spots or traps [74]. Also, more attraction of Cx. quinquefasciatus, Cx. sitiens, and An. epiroticus to black trapping boxes were reported [75]. Khemrattrakool et al. (2019) demonstrated the most of the mosquitoes found in the back UBs were blood-fed females [76], evidence similar to what was observed in the current study. Our finding revealed that, baited RBs more collected unfed mosquitoes, which are important to identifying the parity rates and addressing the situation of malaria transmission., which are important to identifying of the parity rates and addressing the situation of malaria transmission. The urine-baited traps provide a useful alternative tool for sampling malaria vector mosquitoes. This method can also be useful to survey adult mosquito mites and fungus infection that merged from any breeding site and then collected by baited RBs.
In the laboratory and field experiments, CO2 at a flow rate of 170 ml/min was the best dose and used to attracting mosquitoes than other doses. Culex pipiens was found the most frequent species followed by An. stephensi, An. dthali, and, An. fluviatilis. Current data approved that Cx. pipiens with non-human preference behavior are more targeted to traps than Anopheles species. In Kashan County, the best method for adult sampling of Cx. pipiens was BG-Sentinel trap with CO2, followed by human baited bed net trap [41].
Agree with our finding, a study determined that the zoophilic species of An. coustani and, An. pretoriensis are more oriented to CO2 rather than anthropophilic species [60] (Dekker and Takken 1998). In the laboratory experiments, we observed a variation among the different concentrations of CO2 for the attractiveness of An. stephensi and, Cx. pipiens. Agree with our finding, a study determined in Tanzania showed that no correlation among the different concentrations of CO2 for the attractiveness of An. gambiae and Cx. quinquefasciatus [25]. Carbon dioxide is an activator of mosquito host-seeking, more ever, Zöllner et al. (2004) reported increase in ambient CO2 levels may reduce the effective range of attraction to their blood hosts [77]. Consequently, Grant et al. (1995) relieved that the variations in CO2 concentration could affect the ability of the vector to host-seeking behavior [78]. Our finding showed that carbon dioxide raised from yeast supply was not attracted by some mosquitoes. This finding agrees with a study performed by Smallegange et al (2005), which suggested an alternative method using carbon dioxide in the field [20]. Agree with our finding, a study determined that, An. gambiae s.s. has been tended to CO2, also dry ice-baited trap was well-operated rather than yeast provided CO2 trap [60, 79].
In contrast, was reported the strong response to carbon dioxide raised from molasses supply in the open field [80]. It should be considered, that climatic factors, such as wind speed fluctuations, affected the amount of released carbon dioxide. It means CO2 was not released at durable concentrations to attract species. In our field area, winds in the low levels become much more uniform at night to early morning, which perhaps may explain a lesser abundance of some species collected by this method.