Florida flower thrips Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae) incidence and associated impact on grapefruit in Citrus Under Protective Screen (CUPS)

Florida flower thrips, Frankliniella bispinosa (Morgan) is an important pest of citrus in Florida. It feeds and reproduces in the flowers and fruits. To reduce or eliminate the citrus pests and diseases, Citrus Under Protective Screen (CUPS) strategy is becoming common particularly for fresh fruit. Although this technique is effective against large pests particularly the most important Asian citrus psyllid vector of huanglongbing, smaller pests such as mites, thrips, citrus leafminer, and scales are regularly encountered in the CUPS. We studied the abundance and the dispersion of F. bispinosa during two bloom seasons in ‘Ray Ruby’ grapefruit (Citrus paradisi; 2019, 2020) in four CUPS and Open Area (OA) controls at the University of Florida- Indian River Research and Education Center, Fort Pierce, FL. These CUPS were constructed with a 50-mesh (0.3 mm) monofilament high-density polyethylene screen. Grapefruit trees were grown on two rootstocks; Sour Orange and US897 and planted in-ground and pots. Frankliniella bispinosa population was notably high in the CUPS compared to the OA with “aggregated” pattern of dispersion when assessed with flower sampling, sticky cards, and tapping. Populations of thrips varied significantly between planting systems-rootstock combination in 2019. Thrip-induced scaring on the fruit was significantly more in the CUPS than OA.