Influence of Weather Parameters and Mango Fruiting Season on Adult Male Mango Infesting Fruit Fly Population Dynamics in Peradeniya, Sri Lanka

Abstract

Fruit flies (Diptera: Tephritidae) are globally recognized as major pests of fruits, causing both direct and indirect damage. Out of over 4000 species of fruit flies, approximately 350 are of significant economic concern. Monitoring pest populations is a key component of Integrated Pest Management (IPM). The dynamics of insect populations are closely influenced by weather conditions in both preceding and subsequent periods. This study aimed to assess the impact of specific weather variables on the fluctuation of adult male mango infesting fruit fly populations in various mango cultivation areas. The fluctuations in the adult male populations of mango fruit flies were monitored at three locations in Peradeniya University premises. Sampling took place twice a month over an eight-months period, using Methyl Eugenol traps, in line with agricultural guidelines recommending three traps per 0.0404 km² at each site. Data on temperature, relative humidity, rainfall, and wind speed were also collected. A total of 27,883 male fruit flies were caught, comprising Bactrocera dorsalis (64.71%), Bactrocera correcta (18.37%) and Bactrocera kandiensis (16.92%). The highest number of fruit flies were recorded at the Meewathura site (52.82%), which consists of a small forest patch near the Mahaweli River, providing a favorable environment for the growth of fruit flies with minimal human interference. The major peak in adult male fruit fly captures across all sites coincided with the mango fruiting season (from early February to late March). The populations showed significant positive correlations (p<0.05) with monthly maximum average temperatures at Meewathura (r=0.501) and Bowalawatta (r=0.453), as well as with monthly average rainfall at Hilda Obeysekara Hall (r=0.289) and Meewathura (r=0.277), indicating that these weather conditions are favorable to fruit fly growth. The use of sex pheromone traps to capture adult male fruit flies can reduce mating possibilities and contribute to population management. Furthermore, knowledge of the peak activity periods and seasonal population dynamics of the principal mango tephritid species is fundamental for developing effective and targeted pest control strategies.

KEYWORDS: Bactrocera, Fruit fly, Methyl Eugenol, Pest Management, Weather parameter