International Journal of Acarology Vol. 37, No. 5, October 2011, 361–366 LIFE-HISTORY FEATURES OF THE MITE PETROBIA HARTI (ACARI: TETRANYCHIDAE) ASSOCIATED WITH OXALIS CORNICULATA L. (OXALIDACEAE) Indranil Roy 1 , Gautam Aditya 1,2 and Goutam Kumar Saha 1 1. Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019. India (e-mails: indranilzoology@gmail.com and gkszoo@gmail.com); 2. Department of Zoology, The University of Burdwan, Golapbag, Burdwan 713104. India (e-mail: gautamaditya2001@gmail.com). (Received 24 August 2009; accepted 25 August 2010) ABSTRACT – Laboratory and field studies on the life history features of the mite Petrobia harti (Acari: Tetranychidae) was carried out to evaluate its status as a pest of the plant Oxalis corniculata L. (Oxalidaceae). In field samples, P. harti populations were highly abundant during the summer months and completely absent in the winter with average density ranging between 0.61 and 6.11 individuals per leaf. The fecundity rate varied between 1.64 and 6.75. The average longevity of the adult mites ranged between 2 and 11 days. A total period of 8–13 days was required to complete the life cycle from egg to adult stage. Further studies on the nature of damage and biochemical changes in leaves caused by the mite P. harti would help to formulate strategies to regulate its population. Key words – Pest-mite, Petrobia harti (Ewing), Oxalis corniculata L., life table, fecundity table. INTRODUCTION Many species of phytophagous mites are pests of different economically important plant species (Jeppson et al., 1975). Among them the tetranychid spider mite Petrobia (=Tetranychina) harti (Ewing, 1909) (Acari: Tetranychidae) has a worldwide distri- bution. Usually associated with Oxalis spp. (Dubitzki and Gerson, 1987), P. harti are also common on other plants in India (Gupta and Gupta, 1994). Our observa- tions on the occurrence of these mites on the medicinal plant Oxalis corniculata L. (Oxalidaceae) [creeping wood sorrel] prompted us to carry out the work related to the seasonal abundance and the life history of the mite P. harti in Kolkata, India. In traditional Indian medicine, the herb O. corniculata is used to increase appetite and to treat cough, piles, dysentery, and skin diseases (Kirtiker and Basu, 1975; Siddique et al ., 2004). Study of P. harti associated with O. corniculata will allow assessment of its pest status and its general life table characteristics. Assessment of life-history characteristics and life- table features is important to develop the required control strategies to combat pests (Gotoh et al., 2003; Adango et al ., 2006). In recent years the life history study of Tetranychus urticae Koch in Asia has revealed that the life-history traits vary with the cultivars of the plants used, like soybeans (Razmjou et al ., 2009). Hence, host plants as factors form an important deter- minant in the biology of the pest organism. In the case of several insect pests of economically important plants, the life-history evaluation helped to frame con- trol strategies with satisfactory results. The findings on the life-history characteristics of the mite P. harti in India will be helpful in that sense. Furthermore, the strain-specific differences in the life-history traits such as fecundity and reproductive efforts, if any, can be assessed by taking into account earlier studies car- ried out on this mite by Koveos and Tzanakakis (1989, 1991) in Greece. MATERIALS AND METHODS Field study – A random sampling (Sutherland, 1997) was carried out between May 2005 and April ISSN 0164-7954 print/ISSN 1945-3892 online © 2011 Taylor & Francis; printed 11 August 2011 DOI: 10.1080/01647954.2010.519720 http://www.informaworld.com