Figure 1 Comparison of three different dominance indices
Note: a-d represents the calculation results of three dominance indexes of four mosquitoes in each year. e is the difference comparison of three dominance indexes of each mosquito species.f represents the difference of coefficient of variation of three dominance indices among mosquito species from 2012 to 2021. * P<0.05;** P<0.01; *** P<0.001.
The results of the three indexes showed that for Culex pipiens pallens and Aedes albopictus, which were widely distributed in space and time, the results of the three indexes were basically consistent, and there was no significant difference between the indexes. For Culex tritaeniorhynchus and Anopheles sinensis with high spatial and temporal distribution heterogeneity, the Time-Space index is significantly lower than Berger Parker index, which is close to the significance level and lower than McNaughton index (Figure 1e). The difference analysis of coefficient of variation showed that the three calculation results had the least impact on Culex pipiens pallens, and the coefficient of variation was 4.63%, significantly lower than the other three mosquitoes.

Discuss

There is no significant difference among the three calculation results of Culex pipiens pallens. The coefficient of variation is significantly lower than that of other mosquitoes, which may be due to the relatively uniform spatial and temporal distribution. The average spatial frequency ratio is 97.8%, and the temporal frequency ratio is 94.4% (Table 1). McNaughton index of Culex tritaeniorhynchus and Anopheles sinensis was lower than Berger Parker index, but the difference was not significant. The percentage of occurrence frequency introduced by McNaughton index failed to significantly distinguish the spatial and temporal heterogeneity of the distribution of Culex tritaeniorhynchus and Anopheles sinensis and Culex pipiens pallens respectively. This may be because McNaughton index uses the overall occurrence frequency. Although the distribution heterogeneity is considered, the resolution is not enough to distinguish. The Time-Space index is significantly lower than Berger Parker index, which may be because the resolution of distribution heterogeneity is improved after the spatio-temporal factors are separated. There are also some problems in the application of Time-Space. The balance of the survey point settings will affect the index results.

Conclusion

The Time-Space index has significantly improved the resolution of species distribution heterogeneity, and can better reflect the true state of relative dominance among species.
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