Nabi Alper Kumral

Olfactory response of the ladybird beetle Stethorus gilvifrons to two preys and herbivore-induced plant volatiles

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 mite-infested 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.

Resistance to chlorpyrifos and lambda-cyhalothrin along with detoxifying enzyme activities in field-collected female populations of European red mite

The levels of susceptibility of populations of the European red mite Panonychus ulmi (Koch) (Acarina: Tetranychidae) collected from apple orchards in the Bursa region of Turkey to the insecticides chlorpyrifos and lambda-cyhalothrin, were determined by a petri leaf disk—Potter spray tower method. When compared with the susceptible population, resistance ratios at the LC50 level ranged from 6.0- to 35.6-fold, and from 0.7- to 5.7-fold for chlorpyrifos and lambda-cyhalothrin, respectively. Kinetic parameters of general esterase activity with α-naphthyl acetate as substrate indicated that an increased activity was present in the resistant populations compared with the susceptible populations. In these strains, 1.5- and 2.2-fold higher Glutathione S-transferase (GST) activity was also detected with the substrate 1-chloro-2,4-dinitrobenzene. General esterase activity gel profiles of these populations were studied by native polyacrylamide gel electrophoresis, but no relationship between resistance ratios and band patterns was detected. The results of this study document a decreased efficacy of chlorpyrifos and lambda-cyhalothrin in field populations of P. ulmi in Turkey, possibly linked to altered activities of esterases and GST.

The colonization preference and population trends of larval fig psylla, Homotoma ficus L. (Hemiptera: Homotomidae)

The colonization preference and population trends of larval fig psylla Homotoma ficus L. were studied in Bursa, northwestern Turkey, from March 2000 to July 2001. Homotoma ficus 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 first larvae averaged 47 DD based on the larval developmental threshold of 10.9°C. Although the population trends of Homotoma ficus larvae were affected by temperature and rainfall, there was only significant relationship between larval abundance and temperature. The first instar larvae significantly 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 fig bud development period. Third to fifth instars colonized significantly greater on the bottom of leaves compared with the stipule and upper surface. In addition, significant linear relationship was found between fig phenology and cumulative larval counts. The importance of the colonization preference of larval instars and the use of fig phenology as well as DD for timing of insecticide treatments are discussed.

Sub-lethal and lethal effects of Datura stramonium L. leaf extracts on the European red mite Panonychus ulmi (Koch) (Acari: Tetranychidae) and its predator, Stethorus gilvifrons (Muls.) (Col.: Coccinellidae)

Ethanol extracts obtained from the leaf of the thorn apple (Datura stramonium L.) (Solanaceae) were examined for lethal and repellent properties against adults of the European red mite Panonychus ulmi (Koch) (Acari: Tetranychidae) and its predator Stethorus gilvifrons (Muls.) (Col.: Coccinellidae) under laboratory conditions. The Petri leaf disc-spray tower method was used. The results showed that D. stramonium leaf extracts were lethal to both the mite and its predator. Furthermore, an increase in the dose of leaf extract caused a significant increase in the death rates of both P. ulmi and S. gilvifrons adults. Probit analysis and parameter estimation showed that the LC50 values of leaf extract were 7097.5 and 1853.9 mg/l at 24 h residual activity for spider mite and ladybird adults, respectively. The mite and ladybird mortality rates associated with the extract were higher at 48 h than at 24 h, with LC50 values of 2013 and 1030 mg/l, respectively. However, the LC90 values of the extract were lower for ladybirds than for spider mites at both 24 and 48 h. According to Pearson’s chi-squared test, both spider mite and ladybird adults showed strong aversions to apple leaf surfaces sprayed with sub-lethal doses of the extract (from 13.72 to 1058.0 mg/l). Moreover, an odour test using a two-choice olfactometer demonstrated that ladybird adults prefer fresh air to the extract odour. These results suggest that D. stramonium extract can be used effectively as a safer phytopesticidal product for the management of P. ulmi in both organic and inorganic apple production, but it is not suitable for use in integrated pest management strategies due to its toxic and repellent effects against S. gilvifrons.

The biodiversity, density and population trend of mites (Acari) on Capsicum annuum L. in temperate and semi-arid zones of Turkey

Abstract This study investigated mite biodiversity and density on Capsicum annuum in temperate (Bursa and Yalova provinces) and semi-arid (Ankara province) zones of Turkey from 2009 to 2010. A total of twenty-six phytophagous, predatory and generalist mite species were established on pepper leaves. Tetranychus urticae (Tetranychidae) was the single predominant species on the plants in all zones, while Phytoseius plumifer, Neoseiulus californicus (Phytoseiidae) and Tarsonemus bifurcatus (Tarsonemidae) were found to be other common species. Mite diversity and density were higher in temperate zone provinces than in Ankara, which has semi-arid conditions. This variation was significantly correlated with high humidity in the temperate zone, but only for phytophagous mites. The highest number of predatory species was found in the temperate zone, a finding also correlated with humidity, but not significantly. Although phytophagous mite diversity was lower than that of predatory mites in both zones, phytophagous mites were more than abundant than both predatory and generalist mites. The current study observed a significantly high population density of T. urticae from late July to mid August of 2010 and 2011. The sharp decline in T. urticae density on pepper was found to be associated with the onset of rainfall in June and September. Consequently, similar population growth patterns in phytoseiids [Neoseiulus bicaudus, N. californicus and Typhlodromus (Anthoseius) recki in Bursa and Yalova; Phytoseius plumifer in Ankara] were found in all zones and in both years. Generally, predatory mite density showed a gradually increasing population growth pattern from late July to early October.

A reservoir weed for mites: Datura stramonium L. (Solanaceae) in the vicinity of cultivated solanaceous plants in Turkey

Twenty-six phytophagous, predacious and generalist mite species were found on the weed species Datura stramonium in the vicinity of solanaceous vegetables from two locations in Turkey during 2009–2010. Of seven species of phytophagous mites, Tetranychus urticae was the predominant species on the weed leaves. Additionally, 15 predacious mite species from seven families were identified: Phytoseiidae, Anystidae, Stigmaeidae, Bdellidae, Ascidae, Ameroseiidae and Iolinidae. Phytoseiidae (nine species) and Iolinidae (one species) were the most abundant predacious mites in the families. The dominant predacious species were Cydnodromus californicus and Pronematus ubiquitus. The Shannon index (H′), a biodiversity parameter of the predacious mites was very high compared to that of phytophagous mites that occurred at a high density. Among four generalist species from three families (Tydeidae, Acaridae and Oribatidae), one species, Zygoribatula microporosa, was found in the Turkish mite fauna. In Ankara, the population density of spider mites on the weed leaves began to increase in early July and peaked three times in late July, early September and mid-October in 2009–2010. In Bursa, the mites emerged in early June and peaked four times in early July, early August, early September and early October in 2010–2011. Cydnodromus californicus and Typhlodromus Anthoseius recki exhibited efficient numerical responses to spider mite populations from early August to early September. However, in Bursa, Sorenson’s coefficient confirmed that there were positive predator–prey associations among spider mites and these predacious mites. Although this weed is a source of predacious species when it is located in the vicinity of tomato fields, D. stramonium may play a role as a reservoir plant for phytophagous mites and permit increasing pest population in areas used for the cultivation of solanaceous vegetables due to predators’ delayed response to spider mite populations.

Interactions among populations of predatory mites and insect and mite pests on olive trees in Turkey

ABSTRACT This study was conducted to determine the population fluctuations and interactions between predatory mites and pests on leaves, shoots, and flower buds of olive trees. Studies were carried out at weekly intervals in four unsprayed olive orchards at Bursa (Turkey), which were located in different ecological areas, during 2007 and 2008. Population fluctuations of predators and pests were monitored by counting individuals on ten 25-cm long shoots collected at different heights from 10 trees in each olive orchard. The mites and mobile small insects were extracted in Berlese funnels and then examined under a stereomicroscope. In this study, the most common pest species found were: Brevipalpus oleae, Aceria oleae, Thrips tabaci, Liothrips oleae, Parlatoria oleae and Saissetia oleae. Although several mite predators, representing the families Phytoseiidae, Erythraeidae, Cheyletidae and Stigmaeidae, were found, members of the family Phytoseiidae dominated. Among the phytoseiid species, Typhlodromus (Typhlodromus) athiasae and Typhlodromus (Anthoseius) recki were found more often, whereas T. (A.) involutus was rarely encountered. Observations conducted at Bursa during the 2 years suggested that in these olive orchards the phytoseiids exist in a clear numerical response to pest species such as B. oleae and the thrips species. In addition, the results indicated that the large phytoseiid populations were a response to the secretions of the scale insects.