Renard, S., Calatayud, P.A., Pierre, J.S., & Le Rü, B.P. 1998 Recognition behavior of the cassava mealybug Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae) at the leaf surface of different host plants.. Journal of Insect Behavior 11: 429-450.

Notes: The testing behaviour and test probing which are a part of host-plant acceptance behaviour were studied in P. manihoti. Attention was focused on the testing behaviour of three plants of the Manihot genus (2 varieties of cassava and a hybrid of cassava and M. glaziovii) and a weed of cassava fields (Talinum sp.). This enabled not only the characterization of the associated behaviour but also demonstration that the mealybug is able to distinguish between different host plants when walking on the leaf. The video description of the test probing of 1st- and 4th-instar larvae on the two cassava varieties shows that the succession of the phases is similar. After a first phase characterized by the repeated intervention of the mealybug sensorial organs, a second phase, more mechanical, with up-and-down head movements, is observed. At this time, the stylets pass through the epidermic and inner tissues. Finally, a third phase, during which the mealybug becomes more agitated, is observed: it stands up using its rear legs and pushes the upper part of its body against the plant. The stylets continue their progression, which is principally intercellular, until they reach the phloem. Longer and longer immobility periods are observed over a period of time. The coupled videocamera and electrical penetration graph technique were used to observe the relations existing between outer and inner plant events, i.e., between the behavioural items and the electrical signals characteristic of the stylet pathway in the plant.