Predicting Fruit Fly Outbreaks with Seasonal Models

Jim Crocker
20th April, 2024

Predicting Fruit Fly Outbreaks with Seasonal Models

Image Source: Natural Science News, 2024

Key Findings

  • In Sri Lanka, the Oriental fruit fly is expected to increase in density from 2020 to 2025
  • Predictions indicate a 20% rise in wet zones, 30% in intermediate zones, 26% in dry zones, and 37% in arid zones by 2025
  • The arid zone may face the highest fruit fly density, while the wet zone may have the lowest by 2025
The Oriental fruit fly, Bactrocera dorsalis Hendel, is a notorious pest that poses a significant threat to fruit crops worldwide. Originating from Asia, this fly has spread to various regions, causing considerable economic damage due to its ability to infest a wide range of host plants. A recent study conducted by the University of Ruhuna[1] has provided new insights into the density variations of this pest in Sri Lanka, a country where comprehensive data on the fly's population dynamics were previously lacking. The study focused on the current (2020–2022) and projected future (2023–2025) density fluctuations of B. dorsalis across different bioclimatic zones in Sri Lanka: wet, intermediate, dry, and arid. Researchers employed fruit fly traps at 40 randomly selected locations to collect data on the monthly density of the pest. The innovative aspect of this research was the use of the SARIMA (Seasonal Autoregressive Integrated Moving Average) model, a statistical technique commonly applied in time series forecasting. This tool helped the scientists determine the best-fit model to predict future density trends of the fruit fly. The results revealed a seasonal pattern in the year-round density of B. dorsalis, with an overall increasing trend from 2020 to 2025. In terms of future predictions, the study forecasts a rise in fly density by 20% in wet zones, 30% in intermediate zones, 26% in dry zones, and a notable 37% in arid zones by the year 2025. The arid zone is expected to experience the highest density, while the wet zone is predicted to have the lowest. The implications of these findings are critical for Sri Lanka's fruit industry. With the anticipated increase in B. dorsalis density, especially in the arid zones, there is an urgent need for effective pest management strategies to mitigate the threat. Incorporating earlier research into this context, studies have shown that B. dorsalis has a history of successful invasions in various regions[2]. The genetic aspects of its invasion process, particularly the population structure and genetic variability, have been explored using microsatellite markers. These studies have indicated that the fly's colonization process is linked to a stable demographic structure, especially in areas with intensive cultivation[2]. This background information supports the findings of the current study by highlighting the adaptability and resilience of B. dorsalis populations. Further, the genetic diversity and demographic history of the fly in India have been examined, revealing a high level of genetic diversity and signs of recent sudden expansion[3]. Such genetic diversity could contribute to the species' adaptability and potential to thrive in different environments, which might explain the forecasted density increases in Sri Lanka. The rapid spread of B. dorsalis, previously known as Bactrocera invadens, in Africa and its impact on agriculture has also been documented[4]. The species has been observed to displace indigenous fruit fly species, such as Ceratitis cosyra, through mechanisms like resource competition and aggressive behavior[5]. This competitive edge could be a factor in the projected population increases in Sri Lanka's bioclimatic zones. In conclusion, the study from the University of Ruhuna not only sheds light on the current and future challenges posed by B. dorsalis in Sri Lanka but also underscores the importance of proactive pest management. The SARIMA model and QGIS color intensity maps offer a novel approach for visualizing and predicting pest density, equipping stakeholders with valuable tools for strategic planning. As B. dorsalis continues to spread, integrating these findings with global data on the pest's behavior and genetics will be essential for developing comprehensive control measures to safeguard the fruit industry both in Sri Lanka and worldwide.



Main Study

1) Seasonal forecasting of Bactrocera dorsalis Hendel, 1912 (Diptera: Tephritidae) in bioclimatic zones of Sri Lanka using the SARIMA model

Published 18th April, 2024

Related Studies

2) Inferences on the population structure and colonization process of the invasive oriental fruit fly, Bactrocera dorsalis (Hendel).

Journal: Molecular ecology, Issue: Vol 16, Issue 17, Sep 2007

3) Genetic analysis of oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) populations based on mitochondrial cox1 and nad1 gene sequences from India and other Asian countries.

Journal: Genetica, Issue: Vol 144, Issue 5, Oct 2016

4) The potential distribution of Bactrocera dorsalis: considering phenology and irrigation patterns.

5) Evidence for competitive displacement of Ceratitis cosyra by the invasive fruit fly Bactrocera invadens (Diptera: Tephritidae) on mango and mechanisms contributing to the displacement.

Journal: Journal of economic entomology, Issue: Vol 102, Issue 3, Jun 2009

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