Fig 1.
Life stages of Aedes albopictus.
The cycle goes from eggs, E, to larvae/pupae (juvenile), J, to newly eclosed (immature) females, I, to mature adult females, A. Adult female mosquitoes lay normal eggs, E, in the summer months or diapausing eggs, Ed, at the end of the season. Diapausing eggs overwinter and are activated by warmer and longer days in spring.
Table 1.
Parameter definitions and values.
References for point estimates are given below, detailed derivation and references of all other parameters are shown in [28]. Environmental drivers are temperature, T, rainfall, R, photoperiod, P, latitude, L, day of year, DOY, and human population density, H.
Fig 2.
The mosquito life cycle with the mature female class split into susceptible, exposed, and infectious females, AS, AE and AI, respectively.
When a susceptible mosquito bites an infected human host, it gets infected (exposed) with a certain probability and changes to the infectious class after a temperature-dependent extrinsic incubation period. Human hosts change from susceptible, HS, over exposed, HE, to infectious, HI, and finally recover, HR. Parameter symbols and mortality arrows are not included for readability.
Table 2.
Additional parameter definitions and values used for disease dynamics with references at the bottom.
Fig 3.
Mainland China’s suitability for Ae. albopictus.
Top: Mosquito presence in 2007 (black triangles) and 2015 (red triangles) and absence for 2007 (cyan dots) and 2015 (blue dots). Bottom: Modelled suitability index (E0) for the period 2006 to 2016. Values above 1 indicate suitable regions, below unsuitable regions. The CMCD climate data set was used to drive the model. Maps were created with Python package Basemap [83].
Fig 4.
Receiver operating characteristic curve.
The black dot represents Youden’s index, the best compromise between specificity (1-False Positive Rate) and sensitivity (True Positive Rate). The area under the curve (AUC) gives the probability of a region with mosquito occurrence getting a higher suitability index than one without.
Fig 5.
Monthly Breteau indices (BIs) in Guangzhou.
Left: The modelled BI in Guangzhou compared to the observed value. BI values above 4 (dashed black line) indicates risk of dengue transmission. Note that BI data for 2009 and 2014 were incomplete. Right: Scatter plot of simulated vs. observed BI values.
Fig 6.
Top: Observed number of weekly human dengue cases from May to December during the 2014 dengue outbreak (blue bars) and simulated weekly cases (red line). Grey shades indicate officially ordered interventions to control the mosquito population [13]. Bottom: Dividing simulated by observed incidence cases gives the relative error.
Fig 7.
Mosquito density in Guangzhou 2014.
Solid line: Modelled adult females (uninfected and infected) during the 2014 dengue outbreak. Dashed lines: Simulated maximum and minimum adult female density during the period 2006–2016. Blue bars: Weekly rainfall. Heavy rainfall in May might have led to the steep increase in observed mosquito numbers in late May/June.
Fig 8.
Maximum density of infected mosquitoes.
Black lines indicate simulations for individual years 2006–2016, the red lines indicate means. Note that these high infectious mosquito densities were only reached if every bite occurred on an infected human. During the 2014 outbreak, infectious mosquito numbers were about 0.0002 infectious females per hectare in our simulation.
Fig 9.
Simulated length of the dengue transmission season (months).
The depicted median was calculated over the 2006–2016 period. Beijing, Jinan, Shanghai and Guangzhou are indicated by black dots. The map was created using the Basemap package in Python package [82].