The spider mites Tetranychus urticae Koch and Panonychus ulmi (Koch) (Tetranychidae) cause severe economic losses to vegetable farms and deciduous fruit orchards in Turkey. One of their predators, the ladybird beetle Stethorus gilvifrons (Muls.) (Col., Coccinellidae), aggregates on miteinfested patches of plants. The present study assessed whether there is a role for herbivore-induced plant volatiles (HIPVs) and/or odors emitted directly from these two mite species in the aggregative response of ladybird beetles. The olfactory responses of the predator females to volatiles from T. urticae-and/or P. ulmi-infested sweet pepper (four cultivars, viz. 'Demre', 'Yalova Carliston', 'Kandil Dolma' and 'Yag Biberi'), kidney bean (cv. 'Barbunya') and apple (M9 rootstock) were investigated using a two-choice olfactometer. Our results showed that HIPVs emitted from both T. urticae-and P. ulmi-infested plants significantly attracted S. gilvifrons adults for all plants except the sweet pepper cv. Yag Biberi. In addition, it was found that volatiles from apple plants infested by T. urticae and, especially, P. ulmi are more attractive for S. gilvifrons females than those emitted by other infested plants. The results also suggest that the odors of T. urticae adults and their products might influence the attraction of S. gilvifrons females.
The colonization preference and population trends of larval Wg psylla Homotoma Wcus L. were studied in Bursa, northwestern Turkey, from March 2000 to July 2001. Homotoma Wcus overwintered at the egg stage on terminal buds and lenticels of shoots. Larval emergence occurred on 30th and 11th March in 2000 and 2001, respectively. Degree-day (DD) accumulations since 1st January indicate that the emergence of Wrst larvae averaged 47 DD based on the larval developmental threshold of 10.9°C. Although the population trends of Homotoma Wcus larvae were aVected by temperature and rainfall, there was only signiWcant relationship between larval abundance and temperature. The Wrst instar larvae signiWcantly preferred the bottom and the inside stipule of leaves. The second instar larvae distributed not only on expanding green tissues but also on both the upper and lower surface of leaves corresponding to the Wg bud development period. Third to Wfth instars colonized signiWcantly greater on the bottom of leaves compared with the stipule and upper surface. In addition, signiWcant linear relationship was found between Wg phenology and cumulative larval counts. The importance of the colonization preference of larval instars and the use of Wg phenology as well as DD for timing of insecticide treatments are discussed.
The Asian chestnut gall wasp Dryocosmus kuriphilus is a global pest of chestnut (Castanea spp.). It has been spreading in Turkey’s forests and orchards since 2014. This pest imposes a big threat to the Turkish chestnut industry, which is among the top producers in the world. Its gall morphology has been related to pest pressure and host cultivar, thus eventually modulating plant damage with heavy impact on growth and fruit production. We compared gall characters (position on plant organ, ratios, dimensions, volumes, number of larval chambers) in wild Castanea sativa, two local cultivars and a Euro Japanese hybrid. Overall, leaf galls were more common (55.36%), followed by the stem (19.6%) and leaf stipule galls (15.29%). The mean number of chamber and volume value of gall types were 1.52-5.93 and 0.43-2.15 cm3, respectively. The highest values were observed in ‘stem gall’. The more gall formation was observed in the wild chestnut trees and ‘Marigoule’ than the other local varieties.
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