Coconut lethal yellowing disease and the Oryctes monoceros beetle: a joint venture against coconut production in Mozambique

The coconut palm, an important cash and subsistence crop, is widely grown in the coastal regions of the tropics, including Mozambique. However, outbreak of an invasive and emerging coconut lethal yellowing disease (CLYD) is now a major challenge for the coconut industry and livelihood of millions of Mozambican. The observed successions of CLYD epidemics in Mozambique, suggest that other factors than plant-insect-phytoplasma triangle might be associated with the current disease trends. This study investigated the impact of Oryctes monoceros beetle on the CLYD epidemic in Mozambique, using questionnaire survey and direct observation in the fields. The results revealed that there was a significant and negative correlation between beetle and CLYD incidence. This negative correlation may be explained by beetle movement from adult CLYD-infected palms to younger palms which pose a great challenge to the replacement of palms lost due to CLYD. Management strategies must therefore stress the role of beetle larvae in palm trunks killed by CLYD and the threat of Oryces beetles to the replacement of death palm with new plantation.