Predicting the global invasion of Drosophila suzukii to improve Australian biosecurity preparedness

Abstract

Predicting biological invasions remains a challenge to applied ecologists and limits pre‐emptive management of biosecurity threats. In the last decade, spotted‐wing drosophila Drosophila suzukii has emerged as an internationally significant agricultural pest as it rapidly spread across Europe and the Americas. However, the underlying drivers of its global invasion remain unstudied, while countries like Australia, presently free from D. suzukii, require robust estimates of spread and establishment potential to aid development of effective preparedness strategies. Here, we analysed the ecoclimatic and human‐mediated drivers of the global invasion of D. suzukii to understand historical spread patterns and improve forecasts of future spread potential. Using a modular approach, climate‐driven population dynamics were linked in space via dispersal processes to simulate spread at continental scales. Combined with biological parameters measured in laboratory studies, the spread model was parameterized and validated on international spread data. Model accuracy was high and was able to predict 83% of regional presence–absence through time in the United States and, without further model fitting, 78% of the variation in the Europe incursion. Omitting human‐assisted spread from the model reduced predictability by over 20%, highlighting the large anthropogenic influence in this modern biological invasion. Economic activity (GDP) rather than human population density was more strongly associated with human‐mediated spread. Simulations predicted that eastern Australian coastal regions, particularly those near major cities with high economic activity, will result in the fastest spread of D. suzukii. Synthesis and applications. Incursions of Drosophila suzukii into Australia will have significant consequences for horticultural industries with the predicted speed of spread making eradication programs extremely difficult. However, the identified areas of significant fruit production, and high environmental suitability and economic activity will form a logical means for prioritizing industry preparedness. In light of our findings, a key component of preparedness strategies will be the ability of fruit producers to rapidly transition to effective management of D. suzukii.

Phylogenetic analysis and designing new primers for molecular identification of Drosophila suzukii

“…suzukii has a wide range of hosts both in its native habitats in Asia and the United States, with small fruits and cherries being the main economic concerns [1,[15][16][17]. Significant damage has been observed in several commercial soft fruits, such as blackberries, blueberries, cherries, raspberries, strawberries, tomatoes, grapes, cherries, figs, kiwis [18][19][20].…”

Global analysis of the seasonal abundance of the invasive pest Drosophila suzukii reveal temperature extremes determine population activity potential

“…Environmental covariates for each monitoring point were constructed from the climatic data, including the mean temperature across the preceding 30 days, as well as the accumulated degree‐days (DD) both below 5 °C and above 25 °C 27,28 . These temperature thresholds approximately represent the lower temperature bounds of development and the decreasing phase of population growth rate, respectively 9 . To calculate these covariates, available minimum and maximum daily temperatures were converted to hourly temperatures with an idealized daily temperature curve that uses a sine curve for daytime warming and a logarithmic decay function for night time cooling with the ‘chillR’ R package 29…”

“…An important tool in integrated pest management strategies is the use of models that predict the spatial and temporal distribution of pests. Recently, species distribution models have shed light on the potential geographical distribution of D. suzukii , and have pinpointed likely invasion points and areas of high suitability requiring extra surveillance efforts 9–12 . However, when a pest is already well established, attention should instead shift to focus on trying to understand temporal patterns in population dynamics to improve pest management.…”

Highly Efficient Temperature Inducible CRISPR-Cas9 Gene Targeting in Drosophila suzukii

“…It was not considered a severe problem for agriculture for decades until it arrived in Europe and North America in 2008, and its subsequent rapid spread on these continents [1,2]. Drosophila suzukii was recently detected on the South American and African continents [3,4], and potential invasions to Australia were predicted based on suitable environments in some regions [5]. It also causes growing damage in the native Asian area, such as China, due to climatic conditions and farming practices [6,7].…”

“…It also causes growing damage in the native Asian area, such as China, due to climatic conditions and farming practices [6,7]. Consequently, D. suzukii has become a serious threat to fruit production and trade in all major continents [5,6,8]. Whole-genome assemblies of D. suzukii have been generated using short and long-read sequencing technologies [9][10][11], and a whole-genome scan for 22 geographic populations has been conducted to detect genetic variants associated with its invasion success [12].…”