A New Formula for Calculating Species Dominance in the Case of
Mosquitoes
Objective: To explore the calculation method of dominance
degree from biomass, time scale and space scale, so as to provide a
reference basis for more realistic reflection of species dominance
degree. Methods: Excel was used for statistical analysis of
mosquito monitoring data in Wuxi from 2012 to 2021, and t-test was used
to test the variability of three calculation methods, namely Time-Space
index, Berger Parker index and McNaughton index. Results: The
three indices of Culex pipiens pallens and Aedes albopictus were
basically consistent, and there was no significant difference between
them; Time-Space index of Culex tritaeniorhynchus and Anopheles sinensis
was significantly lower than Berger-Parker index (P<0.05), and
was close to the significant level (P=0.0762, P=0.0621) lower than
McNaughton index; The difference of coefficient of variation among the
three calculated results was 4.63%, which was significantly lower than
that of the other three mosquitoes (P<0.05).Conclusion: Time-Space index can significantly improve the
resolution of species distribution heterogeneity, and better reflect the
true state of relative dominance among species.
Species dominance refers to the status and role of a species in a
biological community, which is used to quantify the dominance of a seed
set on the total abundance of a community [1].
Studying the species dominance of a community is helpful to determine
the evenness of species distribution in the community and determine the
dominant species. It is widely used in community ecology research and
species diversity protection. Species dominance is mainly reflected in
the individual number, biomass, volume, frequency and other aspects of
the species. Due to the differences in living conditions, activity types
and other characteristics, different species have different methods to
calculate the dominance. Simpson [2], Lloyd[3], Austin [4], etc.
calculate the species dominance based on the number of individuals and
species in the community; McNaughton index is used to determine the
dominant species of plankton according to the overall occurrence
frequency and individual number of species, and it is also widely used
at present [5]. From the perspective of material
circulation and energy flow in the ecosystem, species dominance refers
to the degree to which a species in the community has an impact on the
material and energy flow of its niche relative to other species. This
includes three latitudes, one is the proportion of the total amount of
material and energy held by the species in the community, the other is
the scale of the impact of the species on the niche on the time scale,
and the third is the scale of the impact of the species on the niche on
the spatial scale. Due to the spatial and temporal heterogeneity of
species distribution, the species dominance can be better reflected only
when these three influence latitudes are fully considered.
Mosquitoes are important medical insects. Different mosquitoes transmit
different diseases, such as malaria transmitted by Anopheles mosquito,
Zika virus disease transmitted by Aedes mosquito, dengue fever, Japanese
encephalitis transmitted by Culex mosquito, etc. Generally, only when
the vector mosquitoes are in the dominant species can the infectious
diseases become widespread. Therefore, the assessment of mosquito
dominance has a strong early warning effect on the assessment of the
epidemic risk of potential mosquito borne infectious diseases within a
certain niche. At present, when the above two mainstream calculation
methods are used to evaluate the dominance of mosquitoes, the results
are inconsistent with the reality [6]. This study
will discuss the calculation method of dominance from the above three
latitudes of biomass, time scale and space scale, and compare it with
the current commonly used methods, so as to provide a reference basis
for more realistic reflection of species dominance.
1.Materials and methods
1.1 data sources
The research data are mosquito monitoring data of Wuxi from 2012 to
2021. From 2012 to 2015, 5 points will be set for residential areas,
parks and hospitals, 4 points for farmers and livestock sheds, 5 points
for each habitat in 2016, and 4 points for each habitat from 2017 to
2021. Mosquito traps are used to conduct mosquito surveys twice from
March to November per year, and the interval between surveys is more
than 10 days. Classify and count the mosquitoes captured. In this study,
urbanization rate was used to reflect the proportion of different
mosquito habitat types in spatial scale. The urbanization rate from 2012
to 2020 is 72.5, 73.4, 74.6, 76.9, 78.1, 79.8, 80.4, 82.0, 82.8% and
82.9% respectively [7].
1.2 Dominance algorithm
\begin{equation}
D_{i}=\frac{b_{i}}{B}\times\frac{t_{i}}{T}\times\frac{s_{i}}{S}\nonumber \\
\end{equation}Where:
Di – relative dominance of species i
B – Total biomass of all species in the community
bi – total biomass of species i
T – Total period of time
ti – total time period of occurrence
of species i
S –total space coverage
si – the total spatial coverage of
species i
Di is the relative dominance of species
i, and the value range is (0,1]. When it is 1, it indicates that the
material and energy flow in the target niche is 100% affected by a
species in terms of biology. T is the total period of
time. The length of the specific period is determined according to the
time scale of the study. ti represents
the time frequency of species in the total period. S is
the total spatial coverage. According to the total area of the niche, it
is the total spatial coverage of the target area.
si represents the total coverage of
species in the area.
1.3 Statistical analysis
The proportion of individual number of each mosquito species in each
year is calculated on an annual basis, which is expressed by\(\frac{n_{i}}{N}\) . The annual occurrence time ratio of each mosquito
species is calculated according to the number of monitored time
sections, which is expressed by \(\frac{t_{i}}{T}\). The spatial
coverage ratio is calculated based on the percentage of points where
species occur, which is expressed by \(\frac{s_{i}}{S}\). Excel is used
for statistical analysis of data, and Adobe Illustrator is used for
graphic layout. T-test was used to test the variability of
different calculation methods.
Results
2.1 Population and distribution of
mosquitos
From 2012 to 2021, the number of monitoring points set varies from 20 to
25, the number of time sections is 18 times a year, 27281 mosquitoes are
captured, and the average mosquito density is 0.6 ind./(lamp.hour).
Mosquitoes mainly include Culex pipiens pallens, Culex
tritaeniorhynchus, Aedes albopictus and Anopheles sinensis. Mosquito
monitoring results over the years are as follows.
Table1 Total number of individuals, number of occurrence points and
number of occurrence time sections of different mosquito species in each
year