Screening of different citrus rootstocks and citrus-related species for resistance to Phyllocnistis citrella (Lepidoptera: Gracillariidae)

Abstract Nine citrus-related species and 349 citrus rootstocks were evaluated under either field or laboratory conditions for resistance to the citrus leafminer, Phyllocnistis citrella (Stainton). Field results confirmed the widespread susceptibility of citrus to the leafminer. Only 0.9% of the trees checked during one growing season escaped damage by flushing once early in the season. Laboratory assays showed that differences among citrus rootstocks existed, but levels of resistance detected were not high enough to establish a breeding program. Contrary to these results, two citroids, Murraya koenigii (L.) Sprengel and Glycosmis pentaphylla (Retzius) Correa, exhibited antibiotic effects against first instar larvae and may provide a source of pest-resistance genes for breeders.