Note: A new pest,Liriomyza trifolii, on cotton in the Büyük Menderes Valley, Turkey
The study was conducted to evaluateLiriomyza trifolii (Burgess) in the cotton fields of the Büyük Menderes Valley, Turkey, from 1999 to 2000. Leaves were sampled weekly from the middle of June to the middle of August and kept in the laboratory to observe emerging leafminers. Leafminers were initially found on cotton leaves from 35 to 66 days after sowing. The numbers of larval mines varied from one to four per leaf. The largest number of infested leaves was observed in Aydın (Center), where 18.8% and 17.7% of the sampled leaves were infested in 1999 and 2000, respectively. We conclude thatL. trifolii is a potential pest in the cotton fields of Turkey and more research is needed.
Seasonal Abundance; Damage; and Comparison of Different Heights, Orientations, and Directions of Yellow Sticky Traps for Sampling of Liriomyza Trifolii (Diptera: Agromyzidae) in Cotton
This study was done to determine the optimum height, orientation, and direction of yellow sticky traps for sampling of Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) in cotton fields. Leaf infestation rates for the whole plants, as well as for each of three plant regions, and number of mines per infested leaf were also determined. Traps were placed at 25 cm above the plant canopy and 30 cm above the ground at two orientations (horizontal and vertical) and two directions (east-to-west and north-to-south) for each height and orientation in Aydin province, Turkey. Horizontally oriented traps captured more flies than vertically oriented traps. More flies were captured 25 cm above the plant canopy than 30 cm above the ground. The upper sides of horizontally oriented traps had the highest capture rates. Direction of traps did not significantly affect capture rate. The infestation rate of leaves was highest (14.1%) the first week of August and generally higher lower on the plant (79.4-100%). No mines were found in the upper region (top third) of the plants. No adults emerged from reared mines. These results are useful in development of sampling protocols to aid growers in making decisions and could be used as an additional component in Integrated Pest Management against L. trifolii in cotton fields. ____________________ Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) is an important pest insect on tomato, celery, chrysanthemum and other commercially valuable plants in several countries (Parrella and Robb 1982, Parrella 1987, Zoebisch and Schuster 1987), including Turkey (Akbulut and Zumreoglu 1996, Yasarakinci and Hincal 1999, Civelek 2004). In addition to vegetables and ornamental plants, L. trifolii damaged cotton in Arizona (USA) (Palumbo 1992), India (Jeyakumar and Uthamasamy 1996), and Israel (Yathom 1989). Sohi et al. (1994) reported that L. trifolii was feeding and breeding on cotton from the cotyledon stage to the vegetative phase until mid-August in India. Larval feeding and adult oviposition in leaves may facilitate entry of fungi and bacteria. Leaf mining reduces rates of photosynthesis, transpiration, and stomatal and mesophyllic conductance causing premature leaf drop (Chandler and Gilstrap 1987, Foster and Sanchez 1988). Gencsoylu (2003) first found L. trifolii in Buyuk Menderes Valley, Turkey, in 1998, and reported that the largest number of infested leaves was observed in Aydin, where 18.8% and 17.7% of the sampled leaves were infested in 1999 and 2000, respectively. These infestation rates were higher than the 2-4% rates found in India (Jeyakumar and Uthamasamy 1996). Some management measures are necessary to control Liriomyza spp. (Parrella 1982, Palumbo et al. 1994). Sticky card traps attract and capture flying adults (hereafter: flies) and can help growers detect early pest activity more effectively than intensive plant sampling and may help to determine the proper time for implementation of control measures. Yellow sticky card traps (hereafter: 1Adnan Menderes University Faculty of Agriculture, Department of Plant Protection, 09100 Aydin, Turkey. (email: igencsoylu@yahoo.com, igencsoylu@adu.edu.tr). 1 Gencsoylu: Seasonal Abundance; Damage; and Comparison of Different Heights, Published by ValpoScholar, 2006 2006 THE GREAT LAKES ENTOMOLOGIST traps) were more attractive to flies than were those of yellow-green, orange, green, and blue (Tryon et al. 1980, Yudin et al. 1987, Park et al. 2001). Heinz et al. (1992) reported on modifications of size and shape of traps and the height and orientation of trap placement that increased the traps’ effectiveness. Trumble and Nakakihara (1983), Zehnder and Trumble (1984), and Zoebisch and Schuster (1990) reported that trap height had a significant influence on the number of flies captured in celery and tomato. Yathom (1989), studying in gerbera greenhouses, found that more flies were caught at 30 cm than at 70 cm above the plant tops and that horizontal and 450 angle traps caught more flies on their upper sides. Weintraub and Horowitz (1996) studied four heights and two orientations of traps in potato fields, where traps placed at the plant height caught significantly more flies than traps placed near the ground or 20 cm or more above plants, but significant differences were not found in the numbers of flies caught on traps placed either horizontally or vertically. As L. trifolii is a new pest in cotton in Turkey, little is known about it except an average infestation rate of cotton leaves (Gencsoylu 2003) — no other studies relating to this pest in cotton in Turkey have been published. This study was done to test the use of traps as a monitoring tool in cotton, and to find the optimum height, orientation, and direction of trap placement. MATERIALS AND METHODS This work was done at the Agricultural Research Center of Adnan Menderes University, Aydin province, in 2004 and 2005. The Nazilli 84-S cotton variety was planted in rows with a north-to-south orientation on 3 May 2004 and 12 May 2005, in the same 0.5 ha field. Standard cultural practices of irrigation and fertilization were followed but no pesticides were applied. The seasonal abundance of L. trifolii, heights, orientations, and directions of traps were studied in one half (0.25 ha) of the field while damage and rates of infestation were studied in the other half (0.25 ha). Plots in the first half were set up in randomized complete block design with three replicates. Each treatment within blocks consisted of 60 rows of 160 m. Traps were in the field over 11 June 17 September 2004, and 17 June 23 September 2005. These were yellow plastic cards (15  10 cm) with >90% reflectance in visible wave length spectrum of 540-600 nm that were placed in the center of each plot and uniformly coated with a thin layer of an adhesive compound mixture of synthetic hydrocarbon polymers (Kapar Organik Tarim Sanayi, Ankara, Turkey) on both sides. Each trap was held in a wooden frame on a wooden rod. Traps at 30 cm above the ground were fixed on the rod, while those at 25 cm above plant canopy could be moved up the rod at each sampling to keep them just above the plant canopy. Traps were oriented vertically and horizontally in both north-to-south and east-to-west directions. East-to-west direction was perpendicular to the rows. Traps were replaced weekly. Traps were brought into the laboratory where flies stuck on each surface were counted under a microscope. These counts were recorded as numbers per side of trap per week. No effort was made to sex the flies trapped. Each week, on the same dates as traps were replaced on one half of the experimental plot, data relating to leaf infestation were collected on the other half of the plot. At each sampling, plant height was measured and divided into three — lower, middle and upper — regions. From 180 plants, 1080 leaves were sampled each week by randomly selecting two leaves from the lower, middle and upper regions of each plant and percentage infestation by plant region was calculated. The infested leaves were put in paper bags and taken to the laboratory where they were examined under a microscope and their mines counted. Mines were not separated into active, dead, or empty. Leaves bearing mines were enclosed in an attempt to rear out flies. 2 The Great Lakes Entomologist, Vol. 39, No. 1 [2006], Art. 4 https://scholar.valpo.edu/tgle/vol39/iss1/4 2 THE GREAT LAKES ENTOMOLOGIST Vol. 39, Nos. & 2 Data relating to trap height, orientation and direction were analyzed using three-way analysis of variance (ANOVA) including all two-way and three-way interactions. Means were separated by TUKEY’S adjustment for multiple comparisons of the means (P <0.05). Data were transformed using log(x+1) before analysis of variance to correct for heterogeneity of variance. Weekly mean for infestation rate (%) of leaves by plant region and percent of mined leaves with different numbers of mine were analyzed by using paired-samples test. All analyses were performed using SPSS version 9.0.1 (1999).
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.