Infestation of the armoured-scale insect Aulacaspis madiunensis (Zehntner) (Hemiptera: Diaspididae) on Cycad plants in the Northern districts of Kerala, India

Cycad plants in Kozhikode and Kannur districts of Kerala, India have been facing an alarming threat from the armoured-scale insect Aulacaspis madiunensis since January 2023. An in-depth investigation from April 2023 to February 2024 revealed the extent of the problem. Both the endemic species Cycas circinalis and the exotic species C. revoluta were affected by the pest. In Kozhikode district 8122 Cycas circinalis and 94 C. revoluta were affected in 23 Grama panchayaths and one municipality. In Kannur district 3856 Cycas circinalis and 62 C. revoluta were affected in 14 Grama panchayaths and 3 municipalities. The mortality rates of affected Cycas circinalis were 0.32% and 0.34% in Kozhikode and Kannur districts respectively. In the case of C. revoluta, the rates were 7.45% and 22.58%. Besides, re-infestation was also observed in a sizeable number of plants. This is the first record of Aulacaspis madiunensis from Kerala and the first record of this species affecting cycad plants in India. While Cycas circinalis is an endangered plant with considerable economic value, C. revoluta is an important ornamental plant. Considering the rapidity with which the infestation is spreading, immediate control measures need to be launched to prevent the possible extinction of these 'living fossils' in Kerala.