(Review Jurnal) Time of Day-Specific Changes in Metabolic Detoxification and Insecticide Tolerance in the House Fly, Musca domestica L.
- House flies, Musca domestica L., a global public health pest which can transmit various pathogens, are primarily controlled by insecticides.
- However, house flies have developed resistance to various kinds of insecticides. So it is urgent to maintain insecticide efficiency.
- Fly exhibits a daily fluctuation of susceptibility to chemicals at different times of the day. And it may influence insecticide toxicity.
- The hypothesis of this experiment was that M. domestica adults exhibited diel rhythms of insecticide susceptibility, in synchrony with their rhythmic behavior of being active to eat during the daytime and being inactive to rest throughout the night.
- Thus, it is necessary to investigated the diurnal variations in beta-cypermethrin susceptibility, metabolic enzyme activities, and several detoxification-related gene expressions in M. domestica across 24 h under environmental light:dark (LD) conditions
a. House Fly Rearing
A filed strain (CFD) of house fly was collected and reared under standard laboratory conditions (25 ± 1?C, RH 60–70%, 16L:8D)
The time of the day in this study was set by Zeitgeber time (ZT) 0, 4, 8, 12, 16, 20, 24, where ZT0 and ZT16 were, respectively defined as when the lights turn on and off in the 16:8 LD condition
Beta-cypermethrin (95.2%) was used for the experiment as a representative member of type II pyrethroids, has been extensively used for house fly control for many years.
c. Biochemical Assay
The house flies were collected every 4 h in a day at ZT0, ZT4, ZT8, ZT12, ZT16, ZT20, and ZT24 with three replications at each point in time, and the protein concentrations of these samples were measured as described by the Bradford method
The detoxivication enzyme activity being observed was P450, Carboxylesterases, and Glutathione S-Transferases
d. Quantitative Real-Time PCR (qRT-PCR)
qRT-PCR was used to determine the rhythmic expression of four selected detoxification genes (CYP6G4, CYP6D1, CYP6D3, MdaE7) which were associated with pyrethroid resistance in the house fly
Rhythmic Susceptibility to Beta-Cypermethrin
Differences in house fly mortality of those exposed to LC50 1.45 mg/cm2 betacypermethrin at different times of day indicate that the house flies possessed rhythmic susceptibility to this insecticide.
b. Daily Rhythms in Enzymatic Activity
Time of day-specific changes in P450 and CarE activities were observed. CarE activities possessed similar patterns between a-NA and b-NA substrates, with peaks at ZT12 and lows at ZT16. Cytochrome P450 enzyme activity continuously increased in the early photophase and reached the highest recorded level at ZT8
c. Rhythmic Gene Expression
For MdaE7, the mRNA expression pattern was similar to the result of the beta-cypermethrin toxicity assay, peaking at ZT12. CYP6D1 was rhythmically expressed with the highest expression level at ZT8. And there is no diel rhythm was observed for CYP6D3 and CYP6G4 expression.
- House flies displayed diel rhythms in beta-cypermethrin susceptibility, peaking at ZT16 and ZT20
- The activities of P450, GST, and CarE enzymes were investigated in our study for determining whether there was a relationship between the diel rhythms in beta-cypermethrin susceptibility and physiological results of detoxification enzymes. That is suggesting that P450 and CarE probably mediate the daily fluctuations of beta-cypermethrin susceptibility in the house fly.
- It has reported that the rhythmic expression of detoxification enzyme genes (CYP6M2, CYP6P3, CYP6Z1, CYP6P3, and GSTD7) were implicated in rhythmic insecticidal detoxification in mosquitoes. The data suggested a potential relationship between the diel rhythms of these genes and insecticide susceptibility to beta-cypermethrin.
- For MdaE7, the mRNA expression pattern was similar to the result of the beta-cypermethrin toxicity assay, peaking at ZT12. CYP6D1 was rhythmically expressed with the highest expression level at ZT8. The data suggested that the gene expression patterns of CYP6D1 and MdaE7 were consistent with the daily fluctuations of P450 and CarE enzyme activities
- No diel rhythm was observed for CYP6D3 and CYP6G4 expression which may be a response to non-circadian physiological metabolism.
There is a relationship between detoxification metabolism and resistance level in M. domestica under environmental light:dark conditions. The house fly was most tolerant to beta-cypermethrin in the late photophase at ZT8 and ZT12
You C, Li Z, Yin Y, Na N and Gao X (2022) Time of Day-Specific Changes in Metabolic Detoxification and Insecticide Tolerance in the House Fly, Musca domestica L. Front. Physiol. 12:803682. doi: 10.3389/fphys.2021.803682