Infestation patterns of a major wood boring pest, Psiloptera fastuosa (Buprestidae: Coleoptera) in Tasar, Terminalia arjuna (Myrtales: Combretaceae) plantation

Abstract

Tasar silk is a significant cash crop in the tropics. In Tasar culture, arjuna (Terminalia arjuna) (Combretaceae) are often planted on farms because the Tasar worm largely consumes their leaves, Antheraea paphia (Lepidoptera: Saturniidae). The wood-boring Psiloptera fastuosa (Coleoptera: Buprestidae) causes severe threats to Tasar plantations during their mating season (September equinox to December solstice). After hatching, the coleopteran grubs puncture and penetrate the arjuna stem, mature into pupae inside, pass into adults, and exit through emergence holes, causing severe damage to younger plants. Though such infestations are highly fatal, no precautions have been proposed to protect the arjuna plantations. Therefore, sustainable Tasar plantation management is highly challenging because of limited bio-ecological information and the infestation pattern of the pest. This study investigates the origins and implications of P. fastuosa infestations in T. arjuna plantations. Our study focuses on seasonal changes in P. fastuosa assaults on its primary host and infestation frequency in an Indian agroecosystem. Second, we examined whether host plant age and size affected the P. fastuosa invasion. The occurrence and distribution of emergence holes for adult beetles on the arjuna bark and the intensity of wood galleries on the stem aid in assessing the beetle infestation. It was observed that 4 to 8-year-old arjuna plants wilted more frequently than younger (< 4 years) and older (> 8 years) plants. Since most infestations occur on the main trunks up to the middle of the plant's height during autumn, insecticidal treatments can be performed around the middle of the main trunks of 4–8-year-old arjuna plants during fall. The findings of this study will benefit the management and propagation of arjuna plants for tropical Tasar silk production.