Kasetsart J. (Nat. Sci.) 49 : 390 - 402 (2015) Population Dynamics and Dispersion of Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae) on Lettuce under Hydroponic Cultivation in Greenhouse Rattigan Submok and Sopon Uraichuen* ABSTRACT Studies were conducted on the population dynamics of Frankliniella schultzei (Trybom) on Iceberg, Red Salad Bowl and Red Rapid lettuce cultivars grown hydroponically at Pathum Thani province, Thailand. In addition, studies were carried out on the dispersion patterns of F. schultzei on hydroponically grown Green Oak Leaf, Red Oak Leaf and Butterhead in Nakhon Pathom province, Thailand. The population of F. schultzei was not detectable in January and February 2012. However, the population clearly increased to its peak in the March planting and then sharply declined in the April planting. The temperature and the relative humidity did not have any effect on the population dynamics of F. schultzei. The dispersion of F. schultzei on the upper side and lower side of lettuce leaves was found to be most abundant at Sampling Point 3 on the upper side of the leaves of all three lettuce cultivars. On the lower side of the leaves of the three cultivars of lettuce, it was most abundant at Sampling Point 5 on Green Oak Leaf and Red Oak Leaf and at Sampling Point 3 on Butterhead only. The populations of F. schultzei, showed a uniform dispersion pattern on Green Oak Leaf and Red Oak Leaf and a clumped dispersion pattern on Butterhead. Keywords: lettuce, hydroponics, Frankliniella schultzei (Trybom), population dynamics, dispersion INTRODUCTION all be grown using hydroponics (Arancon et al., 2005; Thongket, 2007). Consumption of vegetables has recently Although growing plants hydroponically increased in Thailand, resulting in greater has many advantages, it creates a suitable popularity of hydroponically grown vegetables environment for pests such as thrips, aphid and among consumers (Thongket, 2007). Hydroponics whitefly to thrive (Van et al., 2008). Thrips can is a technique for growing plants including cause direct damage to vegetables, for example, vegetables in water containing dissolved nutrients tipburn on lettuces and silver leaf on tomatoes without using soil (Ernst and Busby, 2009). (Thompson, 1926 Jones, 2005;). The thrips species Growing vegetables using hydroponics offers commonly found in hydroponics lettuces include the advantage of producing large quantities of Frankliniella occidentalis (Pergande) (Liu, 2011), vegetables in a relatively small area. Lettuce, F. fusca (Hinds) (Natwick et al., 2007; Wilson, pakchoi, tomato, sweet pepper and cantaloupe can 1998), F. schultzei (Trybom), and Thrips tabaci Department of Entomology, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom 73140, Thailand. * Corresponding author, e-mail: [email protected] Received date : 17/08/14 Accepted date : 15/12/14 Kasetsart J. (Nat. Sci.) 49(3) 391 Linderman (Burfield, 2009; Diffie and Riley, and by density independent (or abiotic) factors, 2009). In addition, the aphid species found on with the latter including temperature, humidity, lettuces include Nasonovia ribis-nigri (Mosley) rainfall, soil pH and food quality (Pongprasert, (Australian Vegetable Grower’s Association, 2005). The relationship between an insect 2002; Cole and Horne, 2004; Palumbo, 2006), species and abiotic factors can be determined by Macrosiphum euphorbiae (Thomas), Uroleucon estimating insect population fluctuations (Roy et ambrosiae (Thomas) (De Conti et al., 2008) and al., 2002). The effect of abiotic factors on insect Myzus persicae (Sulzer) (Rekika et al., 2009). population fluctuations has been reported for In Thailand, F. schultzei was found on thrips species (Panicker and Patel, 2001), cotton sacred lotus, chrysanthemum, bean, cotton, pepper, leafhopper, Amrasca biguttula biguttula (Ishida) onion and cucumber (Poonchaisri and Sengsim, (Gogoi and Dutta, 2000) and whitefly, Bemisia 1993). Elsewhere F. schultzei has been reported, tabaci (Gennadius) (Murugan and Uthamasamy, on the leaves of French bean, Irish potato and baby 2001; Umar et al., 2003). corn (Nyasani et al., 2009) and also on the flowers The objectives of this paper were to of eight plant species—namely, Malvaviscus study the population fluctuations and dispersion arboreus Cav., Hibiscus rosasinensis L., Vigna patterns of F. schultzei and the influences of caracalla L., Erythrina crista-galli L., Bauhinia temperature and humidity on thrips populations galpinii N.E. Brown, Bauhinia variegata L., under hydroponic conditions. Ipomoea cairica Sweet and Jacaranda mimosifolia D. Don (Milne and Walter, 2000). In addition, F. MATERIALS AND METHODS schultzei was also reported on flowers of tomato, chili pepper, onion (Adkins et al., 2009) and The study was carried out in two sunflower (Nyasani et al., 2009). separate greenhouses covered with fine mesh nets The spatial distribution of different (206.40 mesh.cm2) in Thailand; one in Mueang species of thrips was studied using six methods to district, Pathum Thani province and the other determine their population dispersions—Taylor’s in Kamphaeng Saen district, Nakhon Pathom power law (Taylor, 1961), Lloyd’s mean crowding province. At each test site, a hydroponics system (Lloyd, 1967), Iwao’s patchiness regression (Iwao was installed to sustain the growth of the tested and Kuno, 1968), the index of dispersion (Patil plants and Iceberg, Red Salad Bowl, Red Rapid, and Stiteler, 1974) and Morisita’s coefficient of Green Oak Leaf, Red Oak Leaf and Butterhead dispersion (Morisita, 1962). In general, insect were grown according to the Nutrient Film populations are known to follow three distinct Technique (Fa Fresh Farm. Co. Ltd., 2012). dispersion patterns—clumped, random or uniform (Southwood, 1978). Among these dispersion Design of hydroponics systems and growing patterns, clumped or aggregated distributions test plants have been reported: for F. occidentalis (Pergande) System A-The hydroponics system on greenhouse cucumber (Cho et al., 2001); installed in Mueang district was constructed for Aeolothrips intermedius Bagnall, F. intonsa using six A-frames (6.25 × 0.85 × 1.33 m) with Trybom, F. occidentalis, T. angusticeps Uzel and a total of 12 hydroponic troughs on both sides of T. tabaci on cotton (Deligeorgidis et al., 2002); the A-frames. For each trough covered in System and for Scirtotrips dorsalis Hood on pepper (Seal A, 24 holes (5 cm in diameter) were drilled to et al., 2006). provide openings for transplanting the seedlings Fluctuations of insect populations are and also to insert physical support for the growth affected by density dependent (or biotic) factors of test plants. Three cultivars of lettuce (Iceberg, 392 Kasetsart J. (Nat. Sci.) 49(3) Red Salad Bowl and Red Rapid) were used with number of thrips present on the leaves sampled was eight tested plants per cultivar grown in each of counted and recorded. The temperature, relative the six troughs. Thus, there were 24 plants per humidity and conditions of the lettuce leaves trough resulting in a total of 144 plants grown on sampled were recorded. each side of the A-frame and a total of 288 plants These data were first transformed by for system A. taking Log N+1 and then subjecting the result to Tukey’s range test to determine whether there was System B-The hydroponics system a significant difference in the relative abundance installed in Kamphaeng Saen district had a of F. schultzei on the three cultivars of lettuce in different design from that of System A. System the greenhouse conditions. The data were also B consisted of five basket-like, pre-fabricated subjected to regression analysis to determine units. Each unit was composed of five plastic their relationship with such abiotic factors as hydroponic troughs (2.0 × 0.80 × 0.85 m), which the temperature and humidity recorded in the were evenly spaced from the top to the bottom greenhouse. of each unit to allow each tested plant to receive maximum light during growth. On each of the Dispersion patterns of F. schultzei in lettuce covered plastic troughs in System B, nine holes (5 grown hydroponically cm in diameter) were drilled to provide openings This study was conducted in Kamphaeng for transplanting of seedlings and also to insert Saen district with one crop sampled from January support for the growth of the tested plants. Three to March 2013 using System B as described above. different cultivars of lettuce (Green Oak Leaf, Red The three lettuce cultivars used in this study were Oak Leaf and Butterhead) were used as the test Green Oak Leaf, Red Oak Leaf and Butterhead. plants. There were three tested plants per cultivar A sample of 50 leaves per cultivar was sampled grown in each of the five troughs in a unit. Thus, at 7 d intervals, resulting in five samplings as it there were 15 plants per cultivar grown in each required 35 d for a lettuce to reach maturation from unit with a total of 45 plants per cultivar grown a seedling starting from 16 DAP until the lettuce in the 5 units. was harvested at 51 DAP. The dispersion patterns of F. schultzei Population fluctuation ofF. schultzei in lettuce on the three lettuce cultivars were determined by grown in a screen house two methods. The first method involved counting This study was conducted in Mueang the number of thrips present at each of the six district during January to August 2012, using the pre-selected sampling points on the upper side of System A procedure as described above. The three the third leaf of each cultivar at: 1) the mid rib at lettuce cultivars used in this study were Iceberg, the leaf apex, 2) the mid rib at the middle of leaf, Red Salad Bowl and Red Rapid. A sample of 100 3) the mid rib at the leaf base 4) the margin of the leaves per cultivar was randomly sampled on a leaf apex, 5) the margin of the middle of leaf and weekly basis. Since it required 35 d for a lettuce 6) the margin of the leaf base (Figure 1a).