Coccinellid predators do not track populations of the Asian citrus psyllid, Diaphorina citri, in citrus in Puerto Rico

Yellow sticky cards were used to survey populations of Diaphorina citri, the vector of Huanglongbing, the most devastating bacterial disease of citrus worldwide. The numbers of coccinellids, potential predators of Diaphorina citri, were also surveyed. Citrus surveyed included a variety of species (Valencia orange, mandarin, lemon), as well as ornamentals Murraya paniculata and Bergera koenigii. The study sites included a range of management models, from zero management to intensively managed orchards, and orchards were located at different elevations on the island. Our results demonstrate that a variety of coccinellids are present at relatively high population densities on citrus. Although coccinellids are reported to be important predators of Diaphorina citri, populations of coccinellids were lowest on hosts with the highest populations of Diaphorina citri, i.e., Murraya paniculata and Bergera koenigii. Aphids were absent from these hosts, but were plentiful on flushing Citrus species. The presence of aphids probably draws coccinellid predators.