A pest outbreak has triggered panic amid the farming community living on the forest fringes in Wayanad district.
The outbreak has been reported at Valluvady area in Noolpuzha grama panchayat. Huge swarms of insects landed on trees and shrubs in nearly two acres of agricultural land near the Wayanad Wildlife Sanctuary. The population was so big that small branches of trees drooped and broke under the weight of the aggregating bugs, said K.K. Suneesh, a farmer at Odappallam Kavala.
Residents were worried about the creatures causing allergy or spreading diseases as an offensive stench emanated from the insects, he added.
After primary observation, the insect was identified as bamboo sap feeder or bamboo seed bug, Udonga montana, belonging to the Pentatomidae family of shield bugs, said K. Ajithkumar, associate director of research, Regional Agricultural Research Station (RARS), Ambalavayal.
The bug is nearly 13-mm-long with yellowish brown colour. It multiplies in large numbers on bamboo, feeding on the shoot and seeds. They affect the regeneration of bamboo as the developing seeds are affected. The bugs lay eggs in clusters on the flowers. The newly hatched young ones were 2-mm-long and black, said Dr. Ajithkumar.
In 1991 and 1992, the insect formed similar large swarms on forest plants, teak, coffee and pepper in Wayanad and Shivamogga in Karnataka.
In July 2014, Udonga was found to aggregate massively on forest trees and crops such as arecanut, pepper, banana, guava and maize in Shivamogga. However, critical observations indicated that they did not feed on any of the trees, said Seena R. Subhagan, assistant professor, Agricultural Entomology, RARS.
A similar outbreak was reported in June 2021 from Vathikudy in Idukki.
The outbreak in Valluvadi area coincided with the mass flowering of bamboo that provided abundant food, said Ms. Subhagan.
Exhaustive feeding on bamboo by the bug has severely affected the flowering and seedling cycle of bamboo in the area which is likely to affect its natural reproduction. So far, no serious feeding injury or yield losses to agricultural crops in the area had been observed, she said.
In natural stands of bamboo, the pest populations are regulated by natural enemies. However, human intervention can have profound effects on the ecological balance and the population dynamics of insects in bamboo forest ecosystems. The pest outbreak was expected to die down within a few weeks due to natural causes, said Ms. Subhagan.