Tracking the movement trajectory of newly emerged adult Chinese citrus flies with insect harmonic radar

Abstract

Abstract Previous work reveals that the adult Chinese citrus fly, Bactrocera minax (Enderlein), emerges from the ground in citrus orchards and presumably disperses to alternate food sources in neighboring shrubs and trees, where it stays and becomes reproductively mature, and then later returns to the orchard to lay eggs. We investigated the trajectories of early emerged adult Chinese citrus flies, which were tracked with portable harmonic radar in 2013, 2014, 2015, and 2016 in four different habitats in Hubei province of China that presumably provided food sources for adults. This study we investigated whether early emerged adult Chinese citrus flies migrate into forests. A total of 47 adults were tracked following release in a citrus orchard. Our results showed that a total of 33 adults released in a citrus orchard flew into the forest, and 14 adults that disappeared during the tracking process in the citrus orchard. A total of 10 adults (in 2014) that were tracked and released in the forest flew to the forest. Of the adult flies investigated, 54.5% flew directly into the forest, while the remaining 45.5% finally arrived in the forest after repeatedly adjusting their trajectories. When there were Castanea mollissima Blume (Fagaceae) in the surrounding forest, the proportion of frequency of adult landing on the plant represented 58.3% and 88.5% of landing on all species in 2014 and in 2015, respectively. We conclude that early emerged adult Chinese citrus flies in the mosaic-type citrus orchard of the hilly terrain landform dispersed into adjacent forest.