Role of weed hosts and the western flower thrips, Frankliniella occidentalis, in epidemiology of Tomato spotted wilt virus in the Çukurova region of Turkey

Surveys of thrips and Tomato spotted wilt virus (TSWV) on weeds were conducted in the eastern Mediterranean region of Turkey during the years 2004–2006. Thrips species were collected by vigorously shaking weedy plants into a white container for 15 sec. Plant material collected during field surveys and plants which were used for mechanical inoculation of TSWV, were tested by DAS–ELISA. The weed species Ranunculus muricatus, Melilotus officinalis, Sinapis arvensis and Portulaca oleracea were used for the virus transmission experiments in an enclosed high plastic tunnel and in cage experiments. Western flower thrips, Frankliniella occidentlis (Pergande) (Thysanoptera: Thripidae), was the most common thrips, inhabiting 80 of the 82 weed species sampled. Adults of F. occidentalis and thrips larvae were significantly more abundant on S. arvensis than on the other weed species sampled (P<0.05). Adult and larval thrips showed peak densities on most weeds in April or May. Summer annual weeds were not good hosts for reproduction of the thrips. A total of 90 samples from 17 plant species belonging to 11 plant families were ELISA positive for TSWV. No TSWV was detected on 65 weed species belonging to 26 plant families. High numbers of plant samples infected by TSWV were obtained in P. oleracea (21 samples) and in R. muricatus (15 samples). In field surveys symptoms of TSWV were detected on only R. muricatus. Incidence of the TSWV on weeds ranged between 5% and 25%. Transmission rates of TSWV by F. occidentalis to the weeds ranged from 33% to 83% in the pepper plastic tunnel and cage experiments.     

First report of Heterorhabditis bacteriophora (Poinar, 1975) (Nematoda: Heterorhabditidae) isolated from the red palm weevil, Rhynchophorus ferrugineus (Oliver, 1790) (Coleoptera: Curculionidae) in Turkey

Infestation levels of the red palm weevil, Rhynchophorus ferrugineus (Oliver, 1790) and its natural enemies on palm trees in recreation areas were investigated in the Adana province of Turkey in 2008. The trunks of dead palms were sampled for R. ferrugineus and for the presence of entomopathogenic nematodes. While 20% of Phoenix canariensis Hort. were found to be killed by R. ferrugineus , only 2 trees from other species, 1 Washingtonia filifera (L. Linden) and 1 Phoenix dactlylifera L., were killed. Only one species of entomopathogenic nematode, Heterorhabditis bacteriophora ( Poinar, 1975 ) (Nematoda: Heterorhabditidae), was isolated from the R. ferrugineus specimens. Seasonal mortality rate in the total larval population (total 565 larval specimens) of R. ferrugineus was 69%. H. bacteriophora resulted in a significant mortality rate (80%) in the pupae population (total 314 pupal specimens). Overall, 70% of the total of 879 pre-adult specimens were found to be fatally infested by the attacks of this nematode. Heterorhabditis bacteriophora killed few adults, corresponding to 2% of the overall mortality rate. It is concluded that H. bacteriophora could be evaluated as a potential candidate for biological control of R. ferrugineus in the Mediterranean region.     

Damage assessment of the leafhopper complex [<Emphasis Type="Italic">Asymmetrasca decedens</Emphasis> (Paoli) and <Emphasis Type="Italic">Empoasca decipiens</Emphasis> Paoli] (Homoptera: Cicadellidae) in cotton

The leafhoppers [Asymmetrasca decedens (Paoli) and Empoasca decipiens Paoli] have only recently become significant pests of cotton in Turkey. Action threshold level (ATL) of this pest complex is uncertain. The effect of leafhoppers on fruit set and development and yields of glabrous varieties, Caroline Queen, Çukurova 1518 and SG 125 was compared under sprayed (at the ATL of ten leafhoppers per leaf) or unsprayed conditions in 2002–2003. Comparisons of sprayed and unsprayed cotton showed that leafhoppers significantly reduced numbers of fruit and yield. Total losses of the fruiting parts (square plus boll) were similar, ranging from 35 to 55% as well as cotton losses varied from 35 to 50%. Numbers of sucking insects (cotton aphid, whitefly and thrips) and also lepidopterian pests (pink bollworm and bollworm) were very low in both years, and they did not affect cotton development. The current regional ATL for the cotton leafhoppers appears to be too high, and it appears that even five leafhoppers per leaf may be sufficient to significantly reduce yields. It is concluded that ATL of the cotton leafhoppers needs to be re-evaluated in cotton fields in Turkey and also other geographic regions which share similar ecological conditions and same leafhopper species.     

Development of a sampling strategy for the leafhopper complex [<Emphasis Type="Italic">Asymmetrasca decedens</Emphasis> (Paoli) and <Emphasis Type="Italic">Empoasca decipiens</Emphasis> Paoli] (Hemiptera: Cicadellidae) in cotton

Studies on development of a sampling strategy for the complex species of leafhoppers, Asymmetrasca decedens (Paoli) and Empoasca decipiens Paoli within glabrous cotton Çukurova 1518 were done in Adana province, Turkey during 2003–2005. The nymphs showed aggregated distribution pattern, but adults regularly distributed on cotton plants with different ages. The leafhoppers were aggregated on the lower leaves of plants with 9 main stem node (MSN). As plants grew to 12 MSN, they typically moved upwards away from damaged lower leaves to less damaged leaves in the middle stratum. The best MSN leaf to sample nymphs or adults of the leafhoppers was the 8th from the apex, when plants had 9–15 MSN. The population density of leafhoppers strongly affected the numbers of leaf samples required. Numbers of samples needed to estimate the densities with 3, 5, and 10 nymphs per leaf sample at the 20% precision level in 0.3 ha area were 33, 12, and 3, respectively. Population densities of the leafhoppers were significantly lower in the early morning (0530–0700 or 0730–0800 h) than those found in other times of a day. This study suggests that leafhoppers could be sample in any time of a day after 0800 h, preferably 1800–1900 h, in June–July period in the Mediterranean region.     

Pest status of the Hawaiian flower thrips,Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae) in lemons in the Mediterranean region of Turkey

Phytoparasitica - The Hawaiian flower thrips, Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae), is a polyphagous and widespread pest in tropical and temperate regions. In 2015, T. hawaiiensis...     

Overwintering biology of the predatory bug,Orius vicinus (ribaut) (Hemiptera: Anthocoridae) under outdoor conditions in the eastern mediterranean region of Turkey

Phytoparasitica - Overwintering biology of Orius vicinus (Ribaut) (Hemiptera: Anthocoridae) was investigated between November 2017 and April 2018 in the Balcalı location of Adana Province,...     

Influence of planting date on the relationship between populations of Frankliniella flower thrips and predatory bug Orius niger in cotton

The influence of three planting dates [mid-March (early-planted), 15 April–15 May (normal-or timely planted) and mid-June (late-planted)] of cotton variety SG 125 on the relationship between populations of Frankliniella flower thrips (Thysanoptera: Thripidae) and the predatory bug, Orius niger (Wolff) (Hemiptera: Anthocoridae) were investigated in Adana province in the Eastern Mediterranean region of Turkey in 2003 and 2004. To facilitate emergences of cotton seedlings in early-plantings, cotton rows were mulched after sowing. Adult Frankliniella occidentalis (Pergande) dominated the thrips populations in flowers and colonized the flowers rapidly with high numbers in early-and normal-planted cotton, while adult F. intonsa (Trybom) were significantly more abundant on flowers in late-planted cotton (P ≤ 0.05). The significantly higher but short-lasted larval developments were detected only in late-planted cotton in both years (P ≤ 0.05). Although some scarring and silvering damage on leaves and bolls caused by larval feedings occurred in the late-planted cotton, Frankliniella flower thrips did not have any detrimental effect on plant developments and cotton yields in any of the plantings. Early- and mulch-planted cotton produced significantly higher numbers of fruiting parts and also cotton yield, followed by normal-planted cotton (P ≤ 0.05). We commented that the lower cotton yield in late-planted cotton were due to physiologically caused abscissions of the fruiting parts under unfavourable climatic conditions. O. niger was an effective predatory insect of Frankliniella thrips in the flowers especially in normal-planted cotton, as it was detected in significantly high numbers and thrips-to-predator ratios were lower. It is suggested that early planting of cotton in March could be a good cultural practice in the Mediterranean region.     

Larval and adult food preferences of the poinsettia thrips <Emphasis Type="Italic">Echinothrips americanus</Emphasis> Morgan, 1913 (Thysanoptera: Thripidae)

Numerous occurrence of Echinothrips americanus Morgan, 1913, a relatively newly established pest in European greenhouses, on a wide spectrum of cultivated plants throughout Slovakia has encouraged us to present current data on its food ecology. Analysing 1,650 plant species, the poinsettia thrips was found on 106 species (48 families) including 19 showing sporadic, 75 moderate and 17 high infestation. Larvae were detected on 25 plant taxa from 13 families, most of them being new hosts. Mature clusters of Acalypha hispida, showing moderate to high infestation level and carrying both larvae and adults, were selected for more detailed statistical evaluation. Preference of adults for upper and lower leaf surface tends to be without statistical significance, the larvae on the contrary were strongly related to the lower side (Pearson’s χ² = 13.3552, P = 0.0013). Concerning the age, increased occurrence was apparent on younger leaves for both larvae and adults. For larvae the nonparametric test gives the statistical difference between three age categories of leaves with the following values: Kruskal–Wallis χ² = 6.6384, P = 0.03618. The statistical significance of age seems to be more crucial for younger shoots, as proved by the statistics for both larvae (Kruskal–Wallis χ² = 8.4852, P = 0.0144) and adults (Kruskal–Wallis χ² = 7.1049, P = 0.0287). Different food preferences of larvae and adults may result in specific approach when applying an effective biological or chemical control. Narrower tolerance of larvae could make them more manageable target in plant protection instead of efforts to control the whole thrips population.     

Influence of weedy field margins on abundance patterns of the predatory bugs <Emphasis Type="BoldItalic">Orius</Emphasis> spp. and their prey,the western flower thrips (<Emphasis Type="BoldItalic">Frankliniella occidentalis</Emphasis>), on faba bean

The influence of weedy field strips on the abundance patterns of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and predatory bugs of Orius spp. (Hemiptera: Anthocoridae), on faba bean and on weeds was investigated in Adana province, Turkey, during 2005–2006. There were two treatments: in one treatment, weeds at the margins and inside the plots were regularly controlled by tillage; in the other treatment no weed control was done. Thrips and Orius were sampled by beating faba bean plants and weeds. Orius niger (Wolff) was the most abundant predatory insect species in faba bean and flowering weeds, with numbers of adults and nymphs significantly greater in plots with weedy margins than in weed-free plots. Flowering weeds did not contribute to the abundance of F. occidentalis on faba bean. Abundance of adults of Orius spp. did not coincide with the abundance of F. occidentalis on faba bean or weeds. There were significant negative associations for numbers of Orius spp. among faba bean and the weed species Lamium amplexicaule L. or Sinapis arvensis L. (P < 0.05), indicating movement of Orius individuals from the weeds to faba bean during March–April. Finally, faba bean and weeds may provide some benefits to predators, such as nectar, pollen, shelter and egg-laying sites rather than as sources of insect prey. Cultivation of faba bean could be useful for conservation and augmentation of beneficial insects, including Orius spp. Furthermore, field margins bearing flowering weeds such as S. arvensis and L amplexicaule should be protected against destructive management practices, because they host considerable numbers of the Orius species.     

Associations betweenFrankliniella spp. andOrius niger populations in cotton

The distribution of theFrankliniella speciesF. occidentalis (Pergande) andF. intonsa (Trybom) (Thysanoptera: Thripidae), and of the predatory bugOrius niger (Wolff) (Hemiptera: Anthocoridae), in various organs of the cotton plant, as well as prey — predator interactions between thrips andO. niger, were investigated over 6 years in cotton fields in the eastern Mediterranean region of Turkey. The highest number of larvae ofFrankliniella spp. were found inhabiting bolls, whereas the adults colonized mainly flowers. The majority of predatory bug nymphs were present on leaves, followed by bolls, whereasO. niger adults visited mostly flowers. The thrips larvae were most likely preyed upon on flowers and squares, and bolls were safe plant parts for thrips, with a low predation rate. An intermediate but relatively high predation rate occurred on cotton leaves. In further field experiments, the effects of insecticide treatment on the relationships betweenO. niger andFrankliniella spp. were investigated. These trials revealed that a higher correlation existed between the numbers of adultO. niger in flowers andFrankliniella spp. in non-treated cotton fields than in insecticide-treated fields. The proportions of prey/predator in flowers ranged from 1.53 to 19.28 and were below four thrips per predator at most sampling dates in some of the non-treated cotton fields. It is concluded thatO. niger is an effective predator that can play an important role in suppressing population increase ofFrankliniella spp. in cotton. http://www.phytoparasitica.org posting May 12, 2006.