The mosquito Aedes aegypti is the primary vector of dengue and is common throughout tropical and subtropical regions. Its distribution is modulated by environmental factors, such as temperature. This study aimed to evaluate the influence of temperature on the life cycle and expansion of Ae. aegypti populations in the cities of Campina Grande, João Pessoa, and Patos. Samples of Ae. aegypti were collected in the three cities and raised in the laboratory. We assessed the life cycles of the three Ae. aegypti populations under six constant temperatures (16, 22, 28, 33, 36, and 39° C), selected on the basis of historical temperature tendencies of each city. We also used existing climate data to calculate projected temperature increases for all three areas. Our results suggest that Campina Grande, João Pessoa, and Patos will experience, respectively, maximum temperature increases of 0.030° C/year, 0.069° C/year, and 0.061° C/year, and minimum temperature increases of 0.019° C/year, -0.047° C/year, and -0.086° C/year. These projected increases will result in temperatures favorable to the Ae. aegypti life cycle, causing rapid population growth. Therefore, Ae. aegypti populations are likely to expand in the mesoregions represented by these cities. Journal of Vector Ecology 41 (1): 1-10. 2016.

BackgroundThe continued use of chemical insecticides in the context of the National Program of Dengue Control in Brazil has generated a high selective pressure on the natural populations of Aedes aegypti, leading to their resistance to these compounds in the field. Fitness costs have been described as adaptive consequences of resistance. This study evaluated the biological and reproductive performance of A. aegypti strains and a field population resistant to temephos, the main larvicide used for controlling mosquitoes.MethodsComparative tests were performed with a resistant field population from the municipality of Arcoverde, Pernambuco State, Brazil, with a high rate of temephos resistance (RR = 226.6) and three isogenetic laboratory strains from the same origin (Araripina municipality, Pernambuco): RecR (RR = 283.6); RecRNEx (RR = 250.5), a strain under a process of resistance reversion; and RecRev (RR = 2.32), a reversed susceptible strain used as an experimental control.ResultsOur study revealed that the absence of selective pressure imposed by exposure to temephos, for five consecutive generations, led to a discrete reduction of the resistance ratio and the response of the detoxifying enzymes. Most of the 19 biological parameters were impaired in the resistant strains and field population. The analysis of the fertility life table confirmed the presence of reproductive disadvantages for the resistant individuals. Similarly, the longevity, body size, and total energetic resources were also lower for the resistant females, except for the last two parameters in the field females (Arcoverde). In contrast, the sex ratio and embryonic viability suffered no interference in all strains or population evaluated, regardless of their status of resistance to temephos.ConclusionsThe reproductive potential and survival of the resistant individuals were compromised. The parameters most affected were the larval development time, fecundity, net reproduction rate, and the generational doubling time. These fitness costs in the natural population and laboratory strains investigated are likely associated with maintaining the metabolic mechanism of resistance to temephos. Our results show that despite these costs, the highly temephos resistant populations can compensate for these losses and successfully overcome the control actions that are based on the use of chemical insecticides.

-The present work aimed at estimating the thermal requirements for the development and the number of generations per year of Aedes aegypti (L.) under natural conditions. The life cycle of A. aegypti populations was studied at constant temperatures of 18, 22, 26, 30 and 34ºC, and 12h photophase. The development period, egg viability and larval and pupal survival were evaluated daily as well as adult longevity and fecundity. The low threshold temperature of development (Tb) and the thermal constant (K) were determined. The number of generations per year in laboratory and fi eld were also estimated. The favorable temperature to A. aegypti development is between 21ºC and 29ºC, and to longevity and fecundity is between 22ºC and 30ºC. The egg to adult basal temperature, thermal constant and the number of generations in fi eld were, in order, 9.5, 8.5, 3.4, 7.1, 13.5ºC; 244.5, 273.9, 298.5, 280.9 and 161.8 degree-days; and 21.9, 23.8, 24.2, 21.1 and 22.1 generations in populations from Boqueirão, Brejo dos Santos, Campina Grande, Itaporanga and Remígio.KEY WORDS: Insecta, vector, biological cycle, temperature RESUMO -O trabalho teve por objetivo determinar as exigências térmicas para o desenvolvimento e estimar o número de gerações anuais de Aedes aegypti (L.) em campo. O ciclo biológico das populações de A. aegypti foi estudado nas temperaturas constantes de 18, 22, 26, 30 e 34ºC, e fotofase de 12h. Foram avaliados, diariamente, o período de desenvolvimento e a viabilidade da fase de ovo, sobrevivência de larva e pupa, longevidade e a fecundidade dos adultos, determinando-se, ainda, os limites térmicos inferiores de desenvolvimento (Tb) e as constantes térmicas (K). Em função dessas variáveis foram estimados os números de gerações anuais do inseto em laboratório e campo. A temperatura favorável ao desenvolvimento de A. aegypti encontra-se entre 21ºC e 29ºC, e para a longevidade e fecundidade os adultos entre 22ºC e 30ºC. As Tb s , K s de ovo a adulto, e o número de gerações anuais em campo foram de 9,5, 8,5, 3,4, 7,1, 13,5ºC; 244,5, 273,9, 298,5, 280,9 e 161,8 graus-dias; e 21,9, 23,8, 24,2, 21,1 e 22,1 gerações para as populações de A. aegypti das regiões de Boqueirão, Brejo dos Santos, Campina Grande, Itaporanga e Remígio, respectivamente. PALAVRAS-CHAVE: Insecta, vetor, ciclo biológico, temperaturaAedes (Stegomyia) aegypti (L.) é um importante vetor em saúde pública devido a seu papel como transmissor de dengue e de febre amarela. É um mosquito com ampla distribuição geográfi ca, predominando nas áreas tropicais e subtropicais situadas entre os paralelos de latitudes 45° Norte e 40° Sul (Forattini 2002) e nas zonas isotermais intermediadas a 20ºC (Gadelha 1985). Devido ao seu hábito antropofílico, A. aegypti apresenta grande capacidade de adaptação a criadouros artifi ciais o que possibilita o aumento de sua população e, por conseguinte, o aparecimento de epidemias de dengue (Lozovei 2001).A temperatura é um dos principais fatores ecológicos que infl ui tanto direta como indiretamente sobre os insetos,...

ABSTRACT. Effects of temperature on life cicle, thermal exigency and number of generations per year estimation of Aedes aegypti (Diptera, Culicidae). The present work aims at estimating, based on a biological study, the thermal exigencies to the development and the number of generations per year of Aedes aegypti (Linnaeus, 1762) (Diptera, Culicidae) in field. The life cycle of the A. aegypti populations has been studied at constant temperatures of 18, 22, 26, 28, 32 and 34 ± 2°C, and 12 hours photophase. The low threshold temperature of development (Tb) and the thermal constant (K) have been determined. The number of generations per year in laboratory and field has also been estimated. The favourable temperature to the A. aegypti development its between 22°C and 32ºC, and to the longevity and fecundity A. aegypti adult its between 22°C and 28ºC. The egg to adult basal temperature, thermal constant and the number of generations in field were, in order, 11.33; 8.99 and 13.61 ºC, 192.3; 213.2 and 116.5 graus-days, and 23; 24.6 and 30.3 generations to A. aegypti populations from Boqueirão

ABSTRACT. Biology and parasitism of Trichogramma atopovirilia Oatman & Platner and Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) on eggs of Spodoptera frugiperda (J.E. Smith) (Lepidoptera, Noctuidae). The parasitism capacity and development of Trichogramma atopovirilia Oatman & Platner and Trichogramma pretiosum Riley were studied in order to select the most suitable species to control Spodoptera frugiperda (J. E. Smith). The experiments were conducted under laboratory conditions at 25±2ºC, 70±10% RH and 14L:10D photoperiod. Both T. atopovirilia and T. pretiosum showed good development and adaptation to S. frugiperda eggs even after being reared for several generations in eggs of Anagasta kuehniella Zeller. However, T. atopovirilia females were more aggressive and showed higher specificity to the pest, with a higher parasitism capacity in eggs laid with different physical barriers and were more accepted by the natural host in comparison with A. kuehniella. Because of the higher parasitism rate and specificity of T. atopovirilia to the pest's egg this species should be given preference to control S. frugiperda.