The Role of Weeds in the Spread of Tomato Spotted Wilt Virus by Thrips tabaci (Thysanoptera: Thripidae) in Tobacco Crops

Abstract

AbstractOviposition of Thrips tabaci, larval development and their potential to acquire Tomato spotted wilt virus (TSWV) from infected Amaranthus retroflexus, Datura stramonium, Lactuca serriola, Solanum nigrum and Sonchus oleraceus plants and the ability of the adults to transmit this virus to these weeds and tobacco (Nicotiana tabacum cv. Basmas) were studied. When a T. tabaci female was given an oviposition period of 4 days, an average of 21 larvae were produced on leaves of D. stramonium, 17.5 on S. nigrum, 16.3 on L. serriola and 14.3 on S. oleraceus. Significantly higher numbers of larvae were found on tobacco (29.5), and lower numbers on A. retroflexus (1.9). In a choice test, when females were placed onto leaves of these weed species and tobacco in a Petri dish, D. stramonium was preferred over tobacco. Equal numbers of larvae emerged on leaves of tobacco, of L. serriola and of S. nigrum. Oviposition was lower on A. retroflexus and S. oleraceus in this test. After the transfer of newborn 24 h old larvae to leaf discs of tobacco or to one of the weeds 87, 84, 82, 71, 64 and 17% became pupa on tobacco, D. stramonium, L. serriola, S. nigrum, A. retroflexus or S. oleraceus respectively. After acquisition of virus by newborn‐24 h old larvae from L. serriola, D. stramonium, S. nigrum and A. retroflexus 69.5, 51.4, 32.6 and 22% of the adults became transmitters. No transmission could be recorded on S. oleraceus due to a high larval mortality. Males appeared to be more efficient transmitters than females. Tobacco was more susceptible to TSWV than petunia and the weed species, while among weeds, S. nigrum was the most and A. retroflexus the least susceptible species.