Infestation, Population Dynamics, and Host Preference of Thrips on Flowering Pummelo Plants

Objective Infestation, population dynamics, and host preferences of thrips on pummelo plants during flowering period were studied for an effective pest control.

Method Traditionally managed pummelo orchards in Pinghe County, Zhangzhou City, Fujian that grew varieties including the conventional red and white pummelos and the newly introduced grapefruit, red grapefruit, and tangelo were surveyed under this study. On sampling dates during pummelo flowering season, varieties of the infested pummelo plants and altitude of the plantation site as well as population of the invading thrips were recorded. Young pummelo fruits damaged by the pests were collected for nutritional quality determination.

Results  Thrip infestation on pummelos was generally manifested with circular scars around the fruit stem and reduced nutrients in the peel and pulp of the affected young fruits. The moisture and protein contents in the peels were significantly decreased, but the ash and total sugar contents increased, while the protein in the pulp slightly declined. In the pummelo flowering stage, the thrip population was mainly comprised of Thrips hawaiensis, Frankliniella intonsa, Scirtothrips dorsalis, andT. anderwsi with T. hawaiensis being the dominant species that contributed 74.9-88.8% of total. The population peaked in early April and significantly affected by both plant variety and plantation elevation. For instance, the pummelo orchards located in high altitude encountered significantly greater numbers of thrips, and the traditional red and white pummelos tended to attract significantly more thrips than the newly introduced varieties, such as grapefruits.

Conclusion The flowering pummelo plants infested by thrips produced unappealing fruits with inferior nutritional quality. Being the dominant infestation species,T. hawaiensis should be prioritized in the prevention and control programs at the orchards. It would also be prudent to include pesticide application time, altitude of plantation location, and species of pummelo involved into consideration for the implementation.