Invasive pests of SE Asian cassava crops: A threat to regional food security and rural livelihoods

During the past decade, cassava in Southeast Asia has come under mounting pressure through an unfortunate coincidence of pest invasions, deficient quarantine, and crop expansion. The region was free of major cassava phytosanitary problems until 2008, when one of the most destructive pests of cassava, Phenacoccus manihoti (Hemiptera: Pseudoccidae), was recorded in Thailand and then in neighboring countries. Other polyphagous invasive mealybugs, such as Paracoccus marginatus, Phenacoccus madeirensis and Pseudococcus jackbeardsleyi, have also recently been recorded on local cassava crops. In certain countries, classical biological control has been implemented for P. manihoti, with mass releases of the parasitoid Anagyrus lopezi. For other mealybug species, an in-depth assessment of identity, abundance and efficacy of locally-occurring natural enemies waits to be conducted. In areas not affected by mealybugs, steps need to be taken to reduce the risk of introduction, monitor for early detection, and develop rapid responses to minimize impacts. At the same time, research is needed to increase the resilience of local cassava cropping systems. Current pest problems on local cassava crops accentuate the value of and need for collaborative research with national, regional and international partners to safeguard the sustainability and profitability of this important crop for the Asia region.