Seasonality and management of stone weevil, Aubeus himalayanus Voss (Curculionidae: Coleoptera): An emerging pest of Indian Jujube (Ziziphus mauritiana L.)

Abstract

The ber (Ziziphus mauritiana Lamarck) is an important fruit crop grown in arid and semi arid regions of India and elsewhere. Nutritionally, the fruits are rich in protein, phosphorus, calcium, carotene and vitamin C. In India, productivity tends to be low because of various biotic stresses such as pests and diseases. Of the various insect pests infesting ber, the stone weevil Aubeus himalayanus Voss (Coleoptera: Curculionidae) is a new threat to ber cultivation in India. This was recorded as a new pest of ber in India for the first time in the state of Andhra Pradesh in 1994. Serious attacks were later reported in Rahuri, Maharashtra and Jobner, in 1996, and in Karnataka during 1998. Recently, infestations of this pest were reported in Bikaner and Rajasthan in 2010 and in Bangladesh in 2009. The females lay their eggs on the stylar end of fruits, or rarely on the distal end. The newly emerged white coloured grubs enter the seeds by making a puncture in the endocarp of the immature fruits, and starts feeding on the soft seed coat. Later it enters the endosperm, feeds on it, and pupates within the seed. The weevil completes its life within a single fruit. The infestation results in severe fruit drop at the initial stage of fruit set. The damage intensity of the stone weevil varies with cultivars; stoned varieties are preferred more than the pulp rich varieties. Periodical monitoring of orchards for weevil incidence is essential for timely implementation of control strategies. Delayed detection makes management difficult as they enter the seed.