EVOLUTIONARY STRATEGIES IN LIFE TABLE CHARACTERISTICS AMONG FERAL AND URBAN STRAINS OF AEDES AEGYPTI (L.)

Low fecundity in the laboratory was found in populations of Aedes aegypti (L.) exhibiting Black tergite (Bt), a phenotype characteristic of the feral A. a. jormosus (Wlk.), whereas high fecundity was found in six domestic populations of A. a. aegypti in which the phenotype was absent. An investigation of the cause of low oviposition toy the feral population indicated that behavioural differences in mating and feeding were not responsible; egg retention was identified as the major factor. Introduction into laboratory procedure of a variable simulating the feral environment, i.e., coconut-shell infusion at the oviposition site, induced a highly significant increase in feral fecundity both through its chemical constituents and visual attraction. Differential response to oviposition site is discussed in relation to the evolution of subspecies of A. aegypti.

Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Differential response to oviposition site by feral and domestic populations ofAedes aegypti(L.) (Diptera: Culicidae)

Leahy

Vandehey

Booth

1978

“…A number of imaginative and interesting papers have recently appeared on life-table characteristics, population dynamics and control of mosquitoes (e.g. Conway, 1970;Crovello & Hacker, 1972;Cuellar, 1969a, b;de Figueiredo et al, 1975;Hacker et al, 1977;Haile & Weidhaas, 1977;Lansdowne & Hacker, 1974;Moon, 1976;Wagner et al, 1975;Weidhaas, 1974;Weidhaas et al, 1971). Although these approaches may be intellectually stimulating, and in some instances focus attention on aspects of biology needing further study and may be able to indicate the control strategies most likely to succeed, I feel there may arise a proliferation of speculative mosquito biology at the expense of the collection of " real " biological data from field populations.…”

Section: Introductionmentioning

confidence: 99%

A critical review of procedures for sampling populations of adult mosquitoes

Service

1977

162

171

A critical review is presented of the many and varied procedures for sampling adult mosquitoes. All sampling methods are subject to bias, but human-bait collections are probably the most reliable single method for detecting and monitoring populations of anthropophilic species. The estimation of realistic man-biting rates, however, remains difficult. The recent advances in computer technology have generated considerable interest in population modelling, with the aim of getting a better insight into the complexities of population dynamics, mosquito control and disease transmission. Although such approaches may be informative, it is stressed that models should be based on meaningful values of the critical parameters and that these are best obtained from field populations. The difficulties of interpreting mosquito collections in both attractant traps, such as animal-baited traps, carbon-dioxide-baited traps and light-traps, and in non-attractant ones, such as Malaise traps, sticky traps, ramp traps, rotary traps, suction traps and vehicle-mounted traps, are described. Suction traps probably provide the least biased catches of aerial populations of mosquitoes, but, if populations as a whole are to be considered, then resting adults also must be adequately sampled, and this may prove difficult. It is emphasised that different trapping techniques usually sample different components of a population, and that the choice of sampling methods depends much on the type and quality of information required. The limitations of using mark-recapture techniques to study adult dispersal and obtain absolute population estimates are discussed, together with the advantages and disadvantages of applying simple and more complex mathematical procedures for analysing recapture data.

“…During the last decade, a considerable amount of information has been collecte on differences in the ecology, behaviour and physiology of both forms (Gillett, 1955a(Gillett, , i 1956Mattingly, 1958Mattingly, , 1967Crovello & Hacker, 1972;Machado-Allison & Craii 1972;Trpis, 1972Trpis, , 1977Trpis et al, 1971;Trpis & Hausermann, 1975;etc.). Littl work has been done on the genetics of behaviour of A. aegypti that has any direi relevance to the systematics and evolution of this species.…”

Section: Introductionmentioning

confidence: 99%

Genetics of house-entering behaviour in East African populations of Aedes aegypti (L.) (Diptera: Culicidae) and its relevance to speciation

Trpis

Hausermann

1978

Samples of larvae of Aedes aegypti (L.) were collected in three principal habitats, domestic, peridomestic and feral, in the Rabai area in eastern Kenya. The samples from the domestic habitat represent the population of the domestic form, A. a. aegypti, and the feral samples from tree holes from Bejumwa Forest represent the feral subspecies, A. a. formosus (Wlk.). The peridomestic samples from steps cut into trunks of coconut palms most probably represent hybrids between the domestic and the feral forms. These samples were brought to the laboratory where they reproduced in high numbers, and crosses were made between the three populations. Adults of the parental populations and those resulting from the crosses were marked with different colours of fluorescent pigments, released in the peridomestic habitat in the Rabai area and subsequently recaptured in biting catches on man in the domestic and peridomestic habitats. The results indicate that domesticity, particularly house-entering behaviour, in A. aegypti is genetically controlled and is a product of the action of several genes. The gene action in terms of house-entering behaviour is additive as can be clearly seen from the recapture data for the various crosses. The percentage entering houses was highest among mosquitoes of the form from inside houses (the domestic A. a. aegypti population (D)) and the percentages decreased progressively through the peridomestic (P) and hybrid forms to the feral population of A. a. formosus (F) in the following manner: D (45·)DP (15 ·5), PD (13·9), P (9·8), DF (5·7), FD (73·), PF (1·5), FP. (0·6) and F (0·6).The recaptures outdoors were in the reverse order, the highest percentage being for F (187·) and the lowest for D (8·5), DP (8·0) and PD (7·7). The data suggest that the larvae from the peridomestic habitat may represent hybrids between the domestic and feral formsA model for the inheritance of behavioural characters in mosquitoes is presented. On the basis of isolating mechanisms and partial hybridisation, it is concluded that A. a. aegypti and A. a. formosus have developed as geographically isolated allopatric populations. This supports the existing polytypic concept of speciation in A. aegypti. Spatial distribution, non-random mating and the existing series of isolating mechanisms indicate that the domestic type form has been introduced into East Africa, most probably on ships.