Methods of molecular discrimination of citrus mealybug from vine mealybug.

The correct identification of pests is a basic requirement in IPM strategies for crop protection. In the case of Planococcus species the discrimination between similar taxa using morphological features is sometimes difficult because it is based on few microscopic characteristics not easily detectable. This is the case of the polyphagous and cosmopolitan mealybug Pl. citri (Risso), closely related to the congeneric Pl. ficus (Signoret). In the last years, given the increasing interest of economic damage of these insects, new methods were developed to distinguish the two species, all based on molecular techniques as RAPD-PCR and multiplex-PCR. With the aim of discriminating the two mealybugs, in our research we used two alternative methods: analysis of the ITS1 region and restriction fragment length polymorphism (RFLP) analysis of the mitochondrial gene cytochrome oxidase subunit I (COI) amplified by PCR. Furthermore, ITS1 analysis adds information on genetic variability of populations, but it requires significant time and is expensive. The PCR-RFLP used in the present study is more reproducible than RAPD-PCR and it is easier to develop than multiplex-PCR. All these methods provide researchers with powerful alternative tools for the rapid, accurate and unequivocal identification of these mealybugs in different agricultural fields, especially for the correct choice of parasitoids in integrated pest management. Moreover these techniques offer a new approach in the knowledge of biology and relationships between mealybugs, their host plants and natural enemies.