Ecological Distribution and Infestation Dynamics of Rice Panicle Mite, Steneotarsonemus spinki Smiley

Field surveys conducted across major rice-growing villages of the North Coastal districts of Andhra Pradesh between 2017 and 2021 confirmed Steneotarsonemus spinki Smiley as the principal factor associated with spikelet sterility and grain discolouration. Mite colonies were predominantly located within the intercellular spaces of the upper leaf sheath and basal midrib regions, producing characteristic necrotic streaks. Infestations began on leaf sheaths during booting and later extended to developing grains. Incidence ranged from 1–15% in most surveyed locations and reached 20–30% in Amadalavalasa. Cultivars such as RNR-15048, BPT-5204 and BPT-3219 recorded higher susceptibility. Mites persisted in stubbles and ratoon rice and survived on associated weeds (Cyperus rotundus, Echinochloa crusgalli, Cynodon dactylon), confirming their role as off-season hosts. Peak populations occurred during the booting and soft dough stages. The study highlights the increasing economic importance of S. spinki in Andhra Pradesh and emphasizes the need for integrated management strategies targeting both the mite and its associated pathogens.