Dispersal within and between citrus orchards and native hosts, and nymphal mortality of citrus psylla, Trioza erytreae (Hemiptera: Triozidae)

Abstract

Adult citrus psylla populations were monitored in commercial citrus orchards. Most psylla were trapped in the northern and southern edge rows. It is recommended that populations are monitored with one yellow sticky trap placed in the most northern, one in the most southern and one in the central row of citrus orchards. This will provide for standardised and reliable monitoring. There was continuous movement of citrus psylla between unsprayed citrus orchard and adjacent indigenous vegetation, indicating that numbers of citrus psylla may be higher in areas where indigenous host plants grow near citrus. Parasitism of psylla nymphs on indigenous host plants was low during the months June to November when psylla breeding on citrus is at its highest. Therefore, movement of psylla parasitoids from indigenous host plants to citrus seem to be of little value and the removal of indigenous host plants is recommended.