Bikasha sp (Coléoptères : Chrysomelidae), agent potentiel pour un contrôle biologique de Bryophyllum delagoense (Rosales : Crassulaceae).

Abstract

The introduction of a plant from one country to another can present risks. Like mother of millions, Bryophyllum delagoense, an endemic plant from Madagascar, introduced in Australia and has become invasive in some regions of this country. In addition, its toxic properties pose a threat to native fauna. The ineffectiveness of the various controls methods places biological control as an alternative for controlling this plant. For this, the inventory of Crassulaceae species and their associated insects was made in southern Madagascar. Adults collected were transported to laboratory and then reared in cages with potted Bryophyllum delagoense under natural conditions. Thus, the plants collected in the field were replanted and were watered every two days. The evaluation of the attack is done every 10 days under a binocular. 20 sites in 3 regions (Atsimo Andrefana, Androy, Anosy) are prospected and 6 species of insects are found on B. delagoense. Bikasha sp is one of the species found. It is present in 4 sites in the Anosy region and only on Bryophyllum delagoense. Laboratory monitoring showed that eggs were laid on the crown and larval development took place inside the roots. The infested plant dies in 30 +/- 2 days. Despite the effectiveness of Chrysomelidae as a biological control agent on many cases, further tests such as host specificity, as well as the ecological conditions favorable to its maintenance and propagation, are still needed to confirm its status as a biological control agent.