Potential for biological control of tent building species of ants associated with Phytophthora palmivora pod rot of cocoa in Papua New Guinea

The tents of different ant species collected from young cocoa trees in their first or second year of bearing and free from visible pod rot, were tested for the presence of Phytopthtora palmivora by inoculating wounded cocoa pods with tent material. Tents of all species harboured viable P. palmivora but those consisting mainly of soil were more frequently positive than plant debris-type tents. Although Anoplolepis longipes, a dominant, ground nesting, non-tent building species sometimes transported inocula in the laboratory, it did not significantly increase black pod infection in the field. Trees infested with the dominant debris tent building species, Technomyrmex albipes, however, had significantly more black pod than those infested with A. longipes or trees without ants. A. longipes forms dense populations and can exclude other dominant ants and some cocoa pests; its introduction may be a potentially economical method of reducing the transmission of P. palmivora in redeveloped cocoa in Papua New Guinea.