influence of myrmecole activity on the population dynamics Toxoptera aurantii in cocoa plantation in Central Cameroon

Toxoptera aurantii is among Hemipteran cocoa pests in Cameroon. Like others aphids, its colonies are maintained by the ants for their honeydew and in return receive many care, but the real impact of this interaction on the population dynamics of T. aurantii and on the extent of their damage are poorly known. A study of the influence of ant activity on the population dynamics of T. aurantii and the impact of their interaction on the damage was conducted in Libellingoï and Minkoameyos, two locations situated in central region of Cameroon from february 2018 to April 2019. In order to carry out this study, a punctual inventory with a monthly monitoring of the myrmecofauna associated with cocoa trees was carried out by the technic of sight collection on flushes, greedy and stems. The assessment of damages was based on the leaves infested number and the number of sheets rolled up. In total, 23 species of ants were recorded on the cocoa trees, but only five species namely Crematogaster striatula, Myrmicaria opaciventris, Camponotus olivieri, Tapinoma sp. Solenopsis sp. were associated with T. aurantii. Population dynamics of T. aurantii varied according to the ants number they were associated with. In both sites, correlation tests were positive and significant when the aphids were associated with C. striatula and associated with a single species of ants. Moreover, in Minkoameyos, number of aphid was positively correlated with those of ants as a whole, as well as with the combination of C. striatula + Tapinoma sp. The association of T. aurantii with the different species of ants had no direct impact on the damages whatever the site. However, ants are potential danger to cocoa trees because their presence promotes an increase in the number of T. aurantii.
Keywords: cocoa tree, Toxoptera aurantii, relationship.