Resistance of 14 accessions/cultivars of Lycopersicon spp. to two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), in laboratory and greenhouse

Fourteen accessions and cultivars of Lycopersicon spp. were studied to evaluate their resistance to two-spotted spider mite, Tetranychus urticae Koch, under laboratory and greenhouse conditions. In vitro studies were carried out using thumbtack and leaf disk bioassays. Lycopersicon hirsutum and L. pennellii accessions supported more mites on the tack. The highest number of eggs (5.15 ± 0.48 eggs / ♀ / d) was recorded on L. pimpinellifolium LA2533 and the lowest number (0 egg / ♀ / d) was recorded on L. hirsutum and L. pennellii accessions. The highest mite mortality and lowest damage score occurred on the leaf disks of L. pennellii and L. hirsutum accessions that were strikingly in contrast to our observations on L. esculentum varieties (Nandi and Sankranthi). The developmental time of the mite was longest (8.61 ± 0.18 days) on leaf disks of L. esculentum NDTVR-73 and shortest (7.18 ± 0.51 days) on L. pimpinellifolium LA2533. In the greenhouse, the mite was unable to establish on L. hirsutum and L. pennellii accessions. Amongst the rest, Nandi and Sankranthi accessions/cultivars supported the highest, while NDTVR-73 supported the lowest mite population. The highest and lowest density of type VI glandular trichomes were recorded on L. esculentum NDTVR-73 (67.33 ± 6.34 trichomes/mm2) and L. pennellii LA2963 (0.79 ± 0.15 trichomes/mm2), respectively. No relation was found between density of type VI trichomes and resistance to the mite. Type IV glandular trichomes were observed only on the foliages of L. hirsutum and L. pennellii. A positive relation exists between the density of type IV glandular trichomes and resistance to the mite. Key words: Tetranychus urticae, survival, oviposition, avoidance, tomato, glandular trichomes Īģ ǀ ƵŶ ƮoƣŹ ƵŵŹŚoƸģ ŢƯƹŚƤƯ ƹ ƶoƳƺĭ Żř ƲoƿLJ žƴoū ƞoƬŤŴƯ ƽŚoƷ Lycopersicon ƶoƴĩ ƶoŝ ŢŞoƀƳ ƽ ƹŵ ƲţŹŚoţ ƶoĪƫ ƽř  Tetranychus urticae Koch  ƵŚĮƄƿŚƯŻō Źŵ ƶƳŚŴƬĭ ƹ ƾsŹźŝ Ŷƃ ŢƀƿŻ ƁƹŹ ƹŵ ŽŚsř źŝ ƾƷŚĮƄƿŚƯŻō šŚƘƫŚƐƯ ƾŬƴs żƳƺoě (thumbtack) ƹ ƾoĭźŝ Ĩoƀƿŵ (leaf disk) ŢoƟźĭ šŹƺoƇ ƶoƳƺĭ ƽŚoƷ Lycopersicon hirsutum ƹ L. pennelii Ƃǀooŝ ƺooě ƽƹŹ ƶooƴĩ ŵřŶooƘţ Ʋƿźooţ żƳ ŶƴŤooƃřŵ řŹ Ƃǀooŝ ƮooŴţ ŵřŶooƘţ Ʋƿźooţ Ñí å ± æÒ Ò ŻƹŹ Źŵ ƵŵŚooƯ źooŝ ƮooŴţ ƽƹŹ L. pimpinellifolium LA2533 Ʈĩ ƹ ƮŴţ ŵřŶƘţ Ʋƿźţ źƠƇ ƶƳƺĭ ƽƹŹ ƽŚƷ L. pennellii ƹ L. hirsutum Ŷoƃ ƵŶƷŚoƄƯ Śě šŹŚƀų ƹ ƶƴĩ Żř ƾƿLJŚŝ źǀƯ ƹ īźƯ ƿ Ĩƀƿŵ ƽƹŹ ƾƴǀ ƾĭźŝ ƽŚƷ L. hirsutum ƹ L. pennellii Ŷƃ ƵŶƿŵ  ƾƫŚůŹŵ Ʈĩ ƶĩ Ʋƿźţ źƯ Ĩƀƿŵ ƽƹŹ šŹŚƀų ƲƿźţLJŚŝ ƹ ƶƴĩ źǀƯ ƹ ī ƾĭźŝ ƽŚƷ ƶƳƺĭ ƽ L. esculentum ƭŚƣŹř Nandi ƹ Sankranthi ƵŶƷŚoƄƯ Ŷƿŵźĭ ƾƳLJƺƏ ƵŹƹŵ Ʋƿźţ ƽ ƾƬƯŚĪţ ÎÕ Í ± ÓÎ í ŻƹŹ Ĩƀƿŵ ƽƹŹ ƾĭźŝ ƽŚƷ L. esculentum NDTVR-73 ƵŚţƺĩ ƹ Ʋƿźţ ƵŹƹŵ ƽ ƾƬƯŚĪţ Òæ å ± æí ì ŻƹŹ ƽƹŹ L. pimpinellifolium LA2533 ƶŝ ŶƯō Ţsŵ ƶoƳŚŴƬĭ Ǝƿřźƃ Źŵ  ƶoŝ ŹŵŚoƣ ŢoƟō ƶƳƺĭ ƽƹŹ ŹřźƤŤsř ƽŚƷ L. pennellii ƹ L. hirsutum ŵƺŞƳ ƲƿLJ ƹ ƭŚƣŹř źĮƿŵ Ʋǀŝ Źŵ ƭŚƣŹř ƶƘƫŚƐƯ ŵŹƺƯ ƽŚƷ Sankranthi ƹ Nandi Ƃǀŝ ŶƴŤƃřŵ řŹ ƶƴĩ ŢǀƘưū Ʋƿźţ  ƾƫŚůŹŵ ƲƿLJ ƶĩ NDTVR-73 Ʈĩ ƹ ŢǀƘưū ƱřżǀƯ Ʋƿźţ Ʈĩ řŹ šŹŚoƀų ƱřżǀƯ Ʋƿźţ Ţƃřŵ Ƃǀŝ Ʈĩ ƹ Ʋƿźţ Ʈĩřźţ Ʋƿźţ ħźĩ ƵŶƛ ƽŚƷ ƕƺƳ ƽř VI ƶŝ ƽƹŹ Ŝoǀţźţ L. esculentum NDTVR-73 ƹ L. pennellii LA2963 èÑ Ó ± èè Óì ƹ æÒ å ± ìî å ƾƬǀƯ źŝ ħźĩ ƖŝźƯ źŤƯ Ŷƿŵźĭ ƁŹŚưƃ ƾƏŚŞţŹř Ʈĩřźţ Ʋǀŝ ħźĩ ƽŚƷ ƵŶƛ ƕƺƳ ƽř 94 Saeidi et al.: Resistance of 14 accessions/cultivars of Lycopersicon spp. … VI ĩ ƶŝ ŢƯƹŚƤƯ ƹ ƶƴ ƽ ŵƺūƹ ƲţŹŚţ Ƴ ŢƃřŶ ħźĩ ƽŚƷ ƵŶƛ ƕƺƳ ƽř IV ƶoƳƺĭ ƽƹŹ ƎƤƟ ƽŚoƷ L. pennellii ƹ L. hirsutum ŶƳŶƃ ƵŶƷŚƄƯ ƾƴƘƯ ƾĮŤƀŞưƷ Ʈĩřźţ Ʋǀŝ ƾŤŞŨƯ ƹ Źřŵ ħźĩ ƽŚƷ ƵŶƛ ƕƺƳ ƽř IV ƶƴĩ ƶŝ ŢƯƹŚƤƯ ƹ ƽ Ţƃřŵ ŵƺūƹ ƲţŹŚţ ƱŚĭĥřƹ ƽŶǀƬĩ Tetranychus urticae  ƮŴţ ŚƤŝ śŚƴŤūř ƽżƿŹ ƺĭ ƶū ƾĮƳźƟ ƥźƧ ƽŚƷ ƵŶƛ ƽř Introduction Two-spotted spider mite (TSSM), Tetranychus urticae Koch, is an important pest of tomato plants, especially during hot and dry weather. Feeding of T. urticae occurs primarily on the leaf surface that affects the rate of leaf transpiration and photosynthesis. Intensity and duration of the mite feedings are negatively correlated with yield (Sances et al., 1979). The short life span, high fecundity and development of resistance to many acaricides make chemical control of the pest particularly difficult. Therefore, a program of integrated pest management is essential for the control of TSSM (Luczynski et al., 1990). A potential alternative method of control is host plant resistance, which may be mediated by glandular trichomes. Wild tomato species, Lycopersicon hirsutum Humb & Bonpl and L. pennellii (Corr) D’Arcy, have been reported as the sources of resistance to many tomato pests (Carter et al., 1989; Weston et al., 1989; Eigenbrode & Thrumble, 1993; Simmons et al., 2003). Resistance in these species has been attributed to both quantitative and qualitative aspects of glandular trichomes (Snyder & Carter, 1984). Sticky and toxic exudates of type IV and VI glandular trichomes of Lycopersicon spp. may entrap, irritate or kill the invader pest (Stoner & Gentile, 1968; Ania et al., 1972; Simmons et al., 2003). Many studies implicated trichome secretions as important resistance factors of wild tomatoes to arthropods. Lycopersicon hirsutum accessions were reported as resistant to T. urticae (Weston et al., 1989) and insect pests such as Spodoptera exigua (Hübner) (Eigenbrode & Thrumble, 1993), Leptinotarsa decemlineata (Say) (Kennedy & Dimock, 1983; Carter et al., 1989) and Helicoverpa zea (Boddie) (Farrar & Kennedy, 1987). Type VI glandular trichomes of L. hirsutum accessions secrete methyl ketones or sesquiterpenes which are toxic or repellent for several arthropod pests (Williams et al., 1980; Weston et al., 1989). The resistance of L. pennellii accessions, to the pests is mostly related to the chemistry and density of type IV glandular trichomes that cover all parts of the plant. Some accessions of L. pennellii are known as the sources of resistance to Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (Goffreda & Mustchler, 1989; Simmons et al., 2003), H. zea and S. exigua (Juvik et al., 1994), Helicoverpa armigera (Hübner) (Simmons et al., 2004), Bemisia argentifolii Bellows & Perring (Liedl et al., 1995) and T. Journal of Entomological Society of Iran, 2012, 32(1) 95 urticae (Resende et al., 2002; Saeidi & Mallik, 2006). Acylsugars are the major secretion of type IV glandular trichomes of L. pennellii (Goffreda & Mustchler, 1989; Juvik et al., 1994). This study was intended to evaluate the survival, oviposition and avoidance strategy of TSSM on different hosts, as well as the response of different Lycopersicon species (damage score) to the mite and finally the role of type IV and VI glandular trichomes in resistance of Lycopersicon species to TSSM. Materials and methods Plant material and leaf sampling The germplasms used in this study were four varieties (Sankranthi, Nandi, Vybhav and Pusa ruby) and one accession (NDTVR-73) of Lycopersicon esculentum Mill., two accessions of L. pimpinellifolium (LA0373 and LA2533), two accessions of L. peruvianum (LA643 and LA2152), three accessions of L. hirsutum (LA1740, LA1777 and LA2860) and two accessions of L. pennellii (LA2580 and LA2963). Lycopersicon esculentum varieties were obtained from Department of Genetic and Plant Breeding, UAS, Bangalore, Karnataka, India, and wild accessions provided by Nunhems ProAgro seeds, Pvt. Ltd., Bangalore, Karnataka, India. Seeds germinated in petri dishes at room temperature. Small seedlings were transferred to plastic trays (26 × 52 cm) with 50 cells containing sterilized vermicompost. After three weeks seedlings were transferred to 25 × 25 cm earthen pots with equal portion of vermicompost and soil and irrigation daily. Plants were placed in an insectarium enclosed with net under natural conditions of photo period, temperature and humidity. Fully expanded young tomato leaves (third leaves below the apical meristem) were used for in vitro studies. Maintenance of the mite stock culture The strain of TSSM used in this study originated from the infested tomato fields at Hebbal Campus, University of Agricultural Science, Bangalore, Karnataka, India in September 2003. Mite rearing was carried out on susceptible variety L. esculentum Sankranthi in the greenhouse (25 ± 5°C, 60 ± 10 RH). The individual mites used for the bioassays were collected and transferred on the plants using a fine painting brush. Mite avoidance on different accessions/cultivars Mite avoidance was measured using thumbtack bioassay with 10 replications according to Weston & Snyder (1990) method. Ten adult female mites were put on top of each 96 Saeidi et al.: Resistance of 14 accessions/cultivars of Lycopersicon spp. … thumbtack and after 2 h, the number of remaining mites was recorded, while the travelling distance on the leaf surface scored as 1 (less than 5 mm), 2 (between 5 to 10 mm) or 3 (beyond 10 mm) for each mite. Mite oviposition, mite mortality and leaf damage score on the accessions/cultivars Mite oviposition, mite mortality and leaf damage score were studied using leaf disk bioassay (Gimenez-Ferrer et al., 1993). Five leaf disks (2 cm in diameter) of each cultivar placed on a layer of absorbent cotton in a plastic petri dish (12 cm in diameter) together with five adult female mites (3-5 days old). Samples were kept in an incubator at 26 ± 1oC, 60 ± 5% RH and a photoperiod of 16: 8 h (L: D). After 72 h, oviposition, mortality and the number of mites that moved into water were recorded on each disk. Leaf damage was calculated on the intensity of damage (Nihoul et al., 1991; Gimenez-Ferrer et al., 1993) after 96 h on a 0 to 6 scale as: no damage, feeding patches < 10%, 10-25%, 26-40%, 41-60%, 61-80% and 81100% of leaf area, respectively. Developmental time of TSSM on different accessions/cultivars Five leaf disks (2 cm in diameter) of each accession or cultivar were placed on a layer of absorbent cotton in a plastic petri dish. Four adult female mites were transferred on each disk for a 12 h period and then removed, leaving 25 eggs on each disk. There was no egg on L. hirsutum and L. pennellii accessions. The eggs on the susceptible variety, L. esculentum Sankranthi, were moved and af