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Fitness cost in field and laboratory Aedes aegypti populations associated with resistance to the insecticide temephos.

Diniz DF, de Melo-Santos MA, Santos EM, Beserra EB, Helvecio E, de Carvalho-Leandro D, dos Santos BS, de Menezes Lima VL, Ayres CF - Parasit Vectors (2015)

Bottom Line: Our 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.The parameters most affected were the larval development time, fecundity, net reproduction rate, and the generational doubling time.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, Aggeu Magalhães Research Center (Centro de Pesquisas Aggeu Magalhães - CPqAM) - Oswaldo Cruz Foundation (Fundação Oswaldo Cruz - Fiocruz), Recife, Brazil. didiegofelipe@gmail.com.

ABSTRACT

Background: The 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.

Methods: Comparative 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.

Results: Our 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.

Conclusions: The 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.

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Related in: MedlinePlus

Reproductive parameters and longevity of Aedes aegypti females from different strains and the field population. a) fecundity (average number of eggs per female); b) fertility (average number of L1/number of eggs/female) c) longevity (average time in days); Columns followed by the same symbol do not differ significantly from each other by Tukey’s test (p < 0.0005)
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Fig3: Reproductive parameters and longevity of Aedes aegypti females from different strains and the field population. a) fecundity (average number of eggs per female); b) fertility (average number of L1/number of eggs/female) c) longevity (average time in days); Columns followed by the same symbol do not differ significantly from each other by Tukey’s test (p < 0.0005)

Mentions: This analysis revealed that the fecundity of resistant females to temephos was reduced to approximately 50 % when compared to the control. Figure 3 presents the data on the fecundity, fertility, and longevity, of the different groups studied. The number of eggs laid per female was significantly higher for the control (RecRev) (F = 93.78; df = 3.164; p < 0.000005) compared with all other resistant strains or populations (Fig. 3a), as was the number of viable individuals (L1) per female (F = 23.9, df = 3.144; p < 0.0005) (Fig. 3b). The average numbers of eggs and L1 were, respectively, 205.4 (±125.5) and 175.5 (±107.5) for the control; 107.3 (±70.6) and 89.2 (±66.6) for RecRNEx; 100.6 (±81.5) and 79.0 (±83.0) for Arcoverde; and 93.0 (±49.1) and 64.7 (±40.8) for RecR.Fig. 3


Fitness cost in field and laboratory Aedes aegypti populations associated with resistance to the insecticide temephos.

Diniz DF, de Melo-Santos MA, Santos EM, Beserra EB, Helvecio E, de Carvalho-Leandro D, dos Santos BS, de Menezes Lima VL, Ayres CF - Parasit Vectors (2015)

Reproductive parameters and longevity of Aedes aegypti females from different strains and the field population. a) fecundity (average number of eggs per female); b) fertility (average number of L1/number of eggs/female) c) longevity (average time in days); Columns followed by the same symbol do not differ significantly from each other by Tukey’s test (p < 0.0005)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4696322&req=5

Fig3: Reproductive parameters and longevity of Aedes aegypti females from different strains and the field population. a) fecundity (average number of eggs per female); b) fertility (average number of L1/number of eggs/female) c) longevity (average time in days); Columns followed by the same symbol do not differ significantly from each other by Tukey’s test (p < 0.0005)
Mentions: This analysis revealed that the fecundity of resistant females to temephos was reduced to approximately 50 % when compared to the control. Figure 3 presents the data on the fecundity, fertility, and longevity, of the different groups studied. The number of eggs laid per female was significantly higher for the control (RecRev) (F = 93.78; df = 3.164; p < 0.000005) compared with all other resistant strains or populations (Fig. 3a), as was the number of viable individuals (L1) per female (F = 23.9, df = 3.144; p < 0.0005) (Fig. 3b). The average numbers of eggs and L1 were, respectively, 205.4 (±125.5) and 175.5 (±107.5) for the control; 107.3 (±70.6) and 89.2 (±66.6) for RecRNEx; 100.6 (±81.5) and 79.0 (±83.0) for Arcoverde; and 93.0 (±49.1) and 64.7 (±40.8) for RecR.Fig. 3

Bottom Line: Our 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.The parameters most affected were the larval development time, fecundity, net reproduction rate, and the generational doubling time.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, Aggeu Magalhães Research Center (Centro de Pesquisas Aggeu Magalhães - CPqAM) - Oswaldo Cruz Foundation (Fundação Oswaldo Cruz - Fiocruz), Recife, Brazil. didiegofelipe@gmail.com.

ABSTRACT

Background: The 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.

Methods: Comparative 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.

Results: Our 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.

Conclusions: The 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.

Show MeSH
Related in: MedlinePlus