Rat volatiles as an attractant source for the Asian tiger mosquito, Aedes albopictus

Abstract

Aedes albopictus is a vector of dengue, chikungunya, and dirofilariasis. Volatile compounds are crucial for mosquitoes to locate their hosts. This knowledge has allowed the identification of attractants derived from human odours for highly anthropophilic mosquito species. in this study, we used rats as a experimental model to identify potential attractants for host-seeking Ae. albopictus females. porapak Q extracts from immature female rats were more attractive to Ae. albopictus females than those from mature and pregnant females, and males. Phenol, 4-methylphenol, 4-ethylphenol, and indole were identified compounds in male, immature, mature, and pregnant female extracts. There were quantitative differences in these compounds among the extracts that likely explain the discrepancy in their attractiveness. Ae. albopictus females were not attracted to the single compounds when was compared with the four-component blend. However, the binary blend of 4-methylphenol + 4-ethylphenol and the tertiary blend of 4-methylphenol + 4-ethylphenol + indole were as attractive as the four-component blend. In the field trials, BGS traps baited with the tertiary or quaternary blends caught more Ae. albopictus females and males than BGS traps without lures. This is the first laboratory and field study to identify compounds that mediate the attraction of Ae. albopictus to one of its hosts. Aedes albopictus (Diptera: Culicidae) is a mosquito native to Southeast Asia, however is a highly invasive mosquito species and is difficult to control 1,2. This mosquito species is considered a secondary vector of dengue, other arboviruses and canine dirofilarisis 2,3. Recently, Ae. albopictus has also been incriminated as a primary vector in epidemics of chikungunya fever (CHIK) in several countries bordering the Indian Ocean, Central Africa and Europe 4,5. In addition, Ae. albopictus has shown a rapid geographical spread in recent decades 6 , as it has high genetic, physiological and ecological plasticity 7. Ae. albopictus is frequently found in suburban and rural areas where open spaces with vegetation predominate. Several studies have reported that this mosquito species feeds on a great number of hosts, such as mammals, birds, amphibians, and reptiles 8-11 , suggesting that Ae. albopictus is an opportunistic mosquito and possibly a vector of zoonotic and human arboviruses. The host-seeking behaviour of mosquitoes is a complex process that involves the use of chemical and physical cues emitted by the hosts 12,13. This knowledge has allowed the identification of different attractant blends derived from human odours for highly anthropophilic mosquito species, including Anopheles spp., Culex quinquefasciatus, and Aedes aegypti 12,14-19. Some of these blends have been evaluated with Ae. albopictus mosquitoes. For example, BG-Sentinel (BGS) traps baited with a BG-lure (ammonia, lactic acid and caproic acid), octenol and CO 2 captured more Ae. albopictus mosquitoes than CDC light traps and gravid traps 20. Further, it was found that the L-lactic acid ...

Aedes albopictus host odor preference does not drive observed variation in feeding patterns across field populations

“…Variation in intra-species attraction among non-human hosts has been reported previously, with attraction varying by physiological stage in rats 48 , stress hormones in zebra finches 49 , and body mass and metabolic rate in house sparrows 50 . The two guinea pig hosts used in our study were both mature females, however they were different ages, with the older of the two being the more attractive.…”

Diverse roles of microbial indole compounds in eukaryotic systems

“…In fresh canine faeces, indole is the most abundant semiochemical that functions as a ‘food‐indicator’ instead of identifying an oviposition resource (Brodie et al ., 2016 ). Recently, it was observed that the presence of indole as a tertiary blend in chemoattractants extracted from rats enhanced its attractiveness to male Asian tiger mosquito ( Aedes albopictus ) (Díaz‐Santiz et al ., 2020 ). Besides acting as a signal, indole compounds can be lethal to insects.…”

Behavioural Responses of Male Aedes albopictus to Different Volatile Chemical Compounds

“…Moreover, the effect of a single compound may be enhanced or diminished, depending on the other compounds that are present. Further investigations should evaluate different blends of these compounds, as many studies have shown that blends are more likely to elicit a response than individual volatiles [ 55 , 56 ]. Wide-scale tests should be performed with individual candidate compounds, and mixtures of compounds, in the environment where the mosquito is found and where trapping is planned, testing different concentrations, formulations and methods of emission.…”