QTL Determining Diel Flight Activity in Male Culex pipiens Mosquitoes

Abstract

Members of the Culex pipiens complex differ in physiological traits that facilitate their survival in diverse environments. Assortative mating within the complex occurs in some regions where autogenous (the ability to lay a batch of eggs without a blood meal) and anautogenous populations are sympatric, and differences in mating behaviors may be involved. For example, anautogenous populations mate in flight/swarms, while autogenous populations often mate at rest. Here, we characterized flight activity of males and found that anautogenous strain males were crepuscular, while autogenous strain males were crepuscular and nocturnal, with earlier activity onset times. We conducted quantitative trait locus (QTL) mapping to explore the genetic basis of circadian chronotype (crepuscular vs. crepuscular and nocturnal) and time of activity onset. One major-effect QTL was identified for chronotype, while 3 QTLs were identified for activity onset. The highest logarithm of the odds (LOD) score for the chronotype QTL coincides with a chromosome 3 marker that contains a 15-nucleotide indel within the coding region of the canonical clock gene, cryptochrome 2. Sequencing of this locus in 7 different strains showed that the C-terminus of CRY2 in the autogenous forms contain deletions not found in the anautogenous forms. Consequently, we monitored activity in constant darkness and found males from the anautogenous strain exhibited free running periods of ~24 h while those from the autogenous strain were ~22 h. This study provides novel insights into the genetic basis of flight behaviors that likely reflect adaptation to their distinct ecological niches.

The Summer Is Coming: nocte and timeless Genes Are Influenced by Temperature Cycles and May Affect Aedes aegypti Locomotor Activity

“…Light transitions, which mimic dawn and dusk, were conducted using gradual increases or decreases of light. We used a maximum light intensity of 1,000 lux ( Gentile et al, 2009 ; Rund et al, 2011 , 2013 ; Leming et al, 2014 ; Rivas et al, 2018 ; Hickner et al, 2019 ).…”

“…For instance, gene expression or quantitative trait locus (QTL) analyses suggest that cryptochrome 2 might be important for the differentiation of chronotypes in mosquitoes. However, this gene does not have an ortholog in Drosophila ( Gentile et al, 2009 ; Rund et al, 2011 , 2013 ; Leming et al, 2014 ; Rivas et al, 2018 ; Hickner et al, 2019 ). Knowledge about the clock of other insects is relatively poor compared to Drosophila and this lack of understanding aggravates public health problems involving the transmission of pathogens by insect vectors such as Aedes aegypti , where the clock determines several characteristics of pathogen transmission, such as locomotor activity, blood feeding, insecticide resistance and oviposition ( Clements, 1999 ; Saunders, 2002 ; Yang et al, 2010 ).…”

Heritability and phenotypic plasticity of biting time behaviors in the major African malaria vectorAnopheles arabiensis

“…The timing of daily activities in other insects has been shown to have a genetic basis, including emergence in Drosophila (43), flight activity in Culex mosquitoes (44), locomoter activity in seed beetles (45) and mating in melon flies (46). Thus, circadian behaviours in insects are commonly under genetic control, with potential to respond to selection.…”

Data_Sheet_1.pdf

“…Light transitions, which mimic dawn and dusk, were conducted using gradual increases or decreases of light. We used a maximum light intensity of 1,000 lux (Gentile et al, 2009;Rund et al, 2011Rund et al, , 2013Leming et al, 2014;Rivas et al, 2018;Hickner et al, 2019).…”

“…For instance, gene expression or quantitative trait locus (QTL) analyses suggest that cryptochrome 2 might be important for the differentiation of chronotypes in mosquitoes. However, this gene does not have an ortholog in Drosophila (Gentile et al, 2009;Rund et al, 2011Rund et al, , 2013Leming et al, 2014;Rivas et al, 2018;Hickner et al, 2019). Knowledge about the clock of other insects is relatively poor compared to Drosophila and this lack of understanding aggravates public health problems involving the transmission of pathogens by insect vectors such as Aedes aegypti, where the clock determines several characteristics of pathogen transmission, such as locomotor activity, blood feeding, insecticide resistance and oviposition (Clements, 1999;Saunders, 2002;Yang et al, 2010).…”