Longitudinal Studies ofAedes aegypti(Diptera: Culicidae) in Thailand and Puerto Rico: Population Dynamics

Abstract

Aspiration collections of adult Aedes aegypti (L.) were made weekly from inside and outside of houses for 3 yr in a rural Thai village (n = 9,637 females and n = 11,988 males) and for 2 yr in a residential section of San Juan, Puerto Rico (n = 5,941 females and n = 6,739 males). In Thailand, temperature and rainfall fell into distinct seasonal categories, but only temperature was correlated with fluctuations in female abundance. Average weekly temperature 6 wk before mosquitoes were collected and minimum weekly temperature during the week of collection provided the highest correlations with female abundance. Accounting for annual variation significantly improved Thai models of temperature and mosquito abundance. In Puerto Rico, temperature, but not rainfall, could be categorized into seasonal patterns. Neither was correlated with changes in female abundance. At both sites the vast majority of females were collected inside houses and most contained a blood meal. Most teneral females were collected outside. Wing length--an indicator of female size--and parity, egg development or engorgement status were not correlated, indicating that feeding success and survival were not influenced by female size. At both sites, females fed almost exclusively on human hosts (> or = 96%), a pattern that did not change seasonally. In Puerto Rico more nonhuman blood meals were detected in mosquitoes collected outside than inside houses; no such difference was detected in Thailand. Gut contents of dissected females indicated that females in the Thai population had a younger age distribution and fed more frequently on blood than did Ae. aegypti in Puerto Rico. Our results indicated that aspects of this species' biology can vary significantly from one location to another and 1 yr to the next.

Hot temperatures can force delayed mosquito outbreaks via sequential changes in Aedes aegypti demographic parameters in autocorrelated environments

“…1A) were obtained by averaging Ae. aegypti abundance from 10 houses (out of a total of 23 monitored houses) in Village 6 (13° 38' N, 101° 18' E) of Hua Samrong Tambon (subdistrict), Plaeng Yao Amphoe (county), Chachoengsao (province) in Thailand using modified vacuum cleaners from June 1990 to May 1993(Scott et al 2000. Samples were restricted to houses because this is the main resting habitat of adult Ae.…”

“…Samples were restricted to houses because this is the main resting habitat of adult Ae. aegypti (Christophers 1960;Scott et al 2000). Maximum Temperature (TMAX) data (Fig.…”

“…Seasonal patterns of rainfall and temperature range in Thailand were within the range of recorded variability for the area (Chaves et al 2012). See Scott et al (2000) for further details on study sites, sampling, and time series data.…”

“…In the case of rainfall, association delays tend to be shorter, between 1 and 4 weeks (Barrera et al 2011;Scott et al 2000) and it can be argued that changes in adult recruitment by rainfall induced generation of larval habitats could underlie the outbreaks (Chase & Knight 2003;Chaves et al 2012;Yang et al 2009a). In this sense, rainfall and associated changes in relative humidity could ease mosquito dispersal (Edman et al 1998) which maybe essential for population persistence even if local mosquito larval sources are not viable, as suggested by metapopulation persistence of locally inviable populations in models that consider dispersal in autocorrelated environments (Roy et al 2005).…”

“…Moreover, several long-term studies on Ae. aegypti abundance have shown the abundance of this mosquito species to be correlated with different environmental factors, primarily rainfall and temperature (Barrera et al 2011;Dibo et al 2008;Foo et al 1985;Ho et al 1971;Oo et al 2011;Schultz 1993;Scott et al 2000;Tonn et al 1970), but also with "socio-ecological" factors such as unreliable water supply (Barrera et al 1993;Padmanabha et al 2010) or lack of community engagement in proper water container disposal (Predescu et al 2007). Similar patterns of association between mosquito abundance and weather fluctuations have been observed in other Aedes spp.…”