Species composition and seasonal occurrence of Diptera associated with passionfruit crops in Colombia

Abstract

The genus Passiflora includes several tropical fruits that are increasingly well-featured in US and European specialty markets. Purple, sweet and yellow passionfruit reach global production levels of >500,000 metric tonnes/year and are established commodities in South America and parts of Africa and the Pacific. Aside from seminal work in Brazil, Passiflora pest biology, ecology and management has received utterly little research attention. In this study, we determined the composition and seasonal dynamics of the Dipteran species complex associated with the three passionfruit crops (i.e., Passiflora edulis f. edulis Sims, P. edulis f. flavicarpa Degener and P. ligularis Juss.) in their principal production regions in Colombia. From 2008 to 2010, bait trapping and field-collection of Passiflora flowers, flower buds and (immature) fruit were carried out to characterize infestation levels by Diptera and associated natural enemies. A total of five Drosophila spp. and eight different species of Lonchaeidae were reported, with the latter representing members of the genera Neosilba and Dasiops. Contrary to the literature, no Tephritid fly adults emerged from >15,000 samples. Although maximum Lonchaeid infestation was 100% in fruits of purple passionfruit and flower buds and flowers of sweet passionfruit, average infestation levels fluctuated between 1 and 15%. Fruits and flower buds with visual damage were up to ten times more likely to contain Lonchaeid larvae, providing the basis for effective sanitation practices. Seasonal Lonchaeid population fluctuations were damped, while abundance differed between geographical zones. Climate-based niche modeling further indicates that several Colombian valleys and mid-altitude mountain ranges provide suitable environments for the most abundant Dipteran, Dasiops inedulis Steyskal. The parasitoid community was composed of two species at particularly low parasitism levels (i.e., at 0.1–0.2%), with Lonchaeid larvae potentially benefiting from both physical and chemical refuges. Our work provides scientifically-based information regarding key herbivores of passionfruit crops, clarifies the susceptibility of Colombia-grown Passiflora spp. to quarantine fruit fly pests, and provides the basis for future integrated pest management (IPM) programs.