Variations in life tables of geographically isolated strains of the mosquito Culex quinquefasciatus

Abstract

Variations in the life tables and other biological attributes of four strains of Culex quinquefasciatus Say (Diptera: Culicidae) from geographically isolated regions of India that had been reared to the fifth generation in the laboratory were assessed under a standardized rearing regime under constant laboratory conditions. Two strains from arid habitats [Jodhpur (JD) and Bikaner (BKN)], one from a semi-arid inland habitat [Bathinda (BTH)], one from a semi-arid coastal habitat [Jamnagar (JMN)] and a standard laboratory strain (LAB) were compared. Horizontal life-table parameters were measured for each strain. Egg mortality ranged from 4.4% (JD and BTH) to 19.5% (BKN). The lowest rate of adult emergence and highest female : male ratio were found in BKN, and the highest rate of adult emergence and lowest female : male ratio were recorded in BTH. The egg-hatching period was longest in BTH and shortest in LAB. The duration from oviposition to adult emergence was longest in JD and shortest in LAB. Females lived longer than males in all strains. The net reproductive rates (R(0) ) of all field-derived strains (122.9-162.2) differed significantly between strains and were significantly greater than that of LAB (107.6). Similarly, both the intrinsic rate of increase (r(m) ) and finite rate of increase (λ) were found to be lower in LAB than in the field strains, but the mean generation time (T) and doubling time (DT) were longest in LAB. For several life-table attributes, JD and BTH clustered together and were more similar to JMN than to BKN and LAB. The results indicate that BTH, BKN and JD can be characterized as r-strategists, more so than JMN. Overall fecundity increased with age. Differences in annual temperature ranges and mean annual rainfall between locations were positively correlated (r = 0.46-0.97) with egg production, female life expectancy, R(0) , r(m) , λ and T. The results suggest that strains of Cx. quinquefasciatus from different geographical areas with contrasting habitats vary in their survival and reproductive strategies accordingly.

Comparison of Biological Attributes ofCulex quinquefasciatus(Diptera: Culicidae) Populations from India

“…quinquefasciatus (Suleman and Reisen [38]), and 80.5%-95.6% in Cx. quinquefasciatus (Suman et al [28]; five populations from India) which are close to the values reported in the present study ( Table 1). The mean development time from egg to adult was found to vary little, with showing a range of ≤1 day (15.4 days in Gorakhpur and 16.5 days in Pune).…”

“…quinquefasciatus collected from Bikaner, Jamnagar, and Bhatinda areas of India [28]. It has been documented that variations in immature mosquito developmental rates depend on habitat conditions [28,[39][40][41][42]. The results obtained in this study also suggest that habitat and environmental conditions play important role in biological attributes of mosquitoes.…”

“…Hence, we assume that life-table parameters derived from data collected from the colonized wild strains represent maximum estimates of their life-table parameters and are likely to reflect true differences between geographically isolated strains. Similar assumptions were made earlier by Reisen et al [30] and Suman et al [28] to compare the life-table attributes of geographically distinct strains of Culex mosquitoes.…”

“…These values were higher than the developmental period reported for Cx. quinquefasciatus collected from Bikaner, Jamnagar, and Bhatinda areas of India [28]. It has been documented that variations in immature mosquito developmental rates depend on habitat conditions [28,[39][40][41][42].…”

“…quinquefasciatus biology and insecticide susceptibility [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Recently, Suman et al [25,28] reported significant variations in morphology among eggs and life table attributes from the four strains of Cx. quinquefasciatus.…”