The greenhouse whitefly Trialeurodes vaporariorum Westwood, 1856 (Hemiptera: Aleyrodidae) is an invasive and highly polyphagous phloem-feeding pest of vegetables and ornamentals. Trialeurodes vaporariorum causes serious damage due to direct feeding and transmits several important plant viruses. Excessive use of insecticides has resulted in significantly reduced levels of susceptibility of various T. vaporariorum populations. To determine the genetic variability within and among populations of T. vaporariorum from Serbia and to explore their genetic relatedness with other T. vaporariorum populations, we analysed the mitochondrial cytochrome c oxidase I (COI) sequences of 16 populations from Serbia and six neighbouring countries: Montenegro (three populations), Macedonia (one population) and Croatia (two populations), for a total of 198 analysed specimens. A low overall level of sequence divergence and only five variable nucleotides and six haplotypes were found. The most frequent haplotype, H1, was identified in all Serbian populations and in all specimens from distant localities in Croatia and Macedonia. The COI sequence data that was retrieved from GenBank and the data from our study indicated that H1 is the most globally widespread T. vaporariorum haplotype. A lack of spatial genetic structure among the studied T. vaporariorum populations, as well as two demographic tests that we performed (Tajima's D value and Fu's Fs statistics), indicate a recent colonisation event and population growth. Phylogenetic analyses of the COI haplotypes in this study and other T. vaporariorum haplotypes that were retrieved from GenBank were performed using Bayesian inference and median-joining (MJ) network analysis. Two major haplogroups with only a single unique nucleotide difference were found: haplogroup 1 (containing the five Serbian haplotypes and those previously identified in India, China, the Netherlands, the United Kingdom, Morocco, Reunion and the USA) and haplogroup 3 (containing the single Serbian haplotype H3 and haplotypes from Costa Rica, the USA and Spanish Canary Islands). Collectively, our data indicate a rather limited value of COI as a genetic marker for discrimination between different T. vaporariorum populations in the investigated area. Possible explanations for the observed lack of COI sequence variability, such as specific genetics of biological invasion and/or the influence of bacterial symbionts that manipulate insect reproduction, are discussed.

The effects of spirotetramat, a tetramic acid derivative, on gross fertility, net fertility, female longevity and the instantaneous rate of increase of two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) were investigated after treatment of female teleiochrysalises (the first assay) and pre-ovipositional females (the second assay). Spirotetramat was applied to the leaf discs by Potter spray tower and the following series of concentrations was applied: 200, 60, 18, 5.4 and 1.62 mg/l. In both assays after 24 h of exposure, surviving females without symptoms of poisoning were used for further procedure. In the first assay, gross fertility of treated females was reduced by 2.4-64.7% and net fertility by 12.4-88.8%, compared to the control. Gross fertility of the females treated with 1.62 and 5.4 mg/l did not significantly differ from the control, whereas all concentrations, except the lowest, significantly reduced net fertility and female longevity. Treatments with 200, 60, and 18 mg/l significantly reduced the instantaneous rate of increase. In the second assay, gross fertility and net fertility were reduced by 43.7-93.3% and 73.8-98.5%, respectively. All concentrations, except the lowest, significantly reduced gross fertility, whereas net fertility and longevity in all treated females were significantly lower compared to the control. All concentrations, except the lowest, significantly reduced the instantaneous rate of increase, provided that concentrations of 200, 60 and 18 mg/l caused population decline. The effects of spirotetramat and its impact on T. urticae management are discussed.

SuMMARYThe effects of five tomato genotypes (cv. Narvik and hybrids NS-6, Tamaris, Alliance and Marko) on the survival, reproduction, development and population growth of the greenhouse whitefly Trialeurodes vaporariorum were examined. A laboratory population of T. vaporariorum had been reared on tobacco plants for three years before the study. Females that laid eggs on the genotype Marko lived significantly longer and their offspring needed significantly shorter periods to develop than females on the genotype Narvik. The highest gross and net fecundity rates were found in females on the genotype Marko (36.74 eggs/ female and 27.93 eggs/female, respectively) and they differed significantly from the corresponding rates of females living on the genotype NS-6 (18.55 eggs/female and 15.33 eggs/ female), who had the lowest fecundity rates. The highest gross and net fertility rates were also found in females on the genotype Marko (31.24 adults/female and 23.73 adults/female), and they were significantly higher than those of females living on NS-6 (14.85 adults/female and 12.53 adults/female). Besides, net fertility rate of the females living on the genotype Narvik (13.80 adults/female) was also significantly lower than the rate of females on Marko. The instantaneous rates of increase showed no significant difference over a 10-day interval following the start of oviposition, while the increase rate was significantly higher on the genotype Marko after 12, 14 and 16 days, compared to the genotype NS-6. Eighteen, 20 and 22 days after the beginning of oviposition, the instantaneous rate of increase on the genotype Marko was significantly higher than it was on NS-6 and Narvik. Our data provide a basis for further research aiming to improve programs of integrated management of greenhouse whitefly.

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Acute toxicity of a buprofezin-based product (commercial product Elisa 440 SC) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of a commercial strain (?Dutch? strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27?1?C temperature and 60?10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In an acute toxicity bioassay, tobacco leaves carrying parasitoid pupae (20 pupae per replicate) were treated with a series of buprofezin concentrations covering a 10-90% mortality range, and mortality was calculated based on the number of emerging adults 9 days after treatment. The following LC50 (mg/l) estimates were obtained: 244.2, 281.5 and 199.5 (for B, N and D, respectively). The product based on buprofezin, applied to parasitoid pupae at concentrations within the LC50s and 95% confidence limits (264 mg/l for B and N; 220 mg/l for D), significantly prolonged the duration of juvenile development (2, 1.7 and 2.2 days for B, N and D, respectively, compared to control data). Females from all tested populations that emerged from the treated pupae and were exposed to the residual action of buprofezin lived shorter than control females (B, N and D by 1.5, 0.7 and 1.7 days, respectively). Also, females that emerged from the treated pupae achieved a significantly reduced level of parasitism (B, N and D by 11.7, 17.7 and 17.6 %, respectively), total adult emergence (B, N and D by 11.6, 17.8 and 17.8 %, respectively) and instantaneous rate of increase (B, N and D by 8.2, 6.8 and 12.5 %, respectively), compared to control. More precise determination of risks involved in the use of buprofezin requires its more detailed field testing. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR31043]

SUMMARYModern crop protection industry puts great efforts into the investigation and development of pesticides (insecticides, acaricides) with a novel mode of action, primarily because of increasingly important problem of resistance of pest organisms to pesticides. Resistance of many pest arthropod species (insects and mites) to insecticides and/or acaricides became a global phenomenon in the last decades. Therefore, pest management heavily relies on constant introduction of novel active ingredients in use, i.e. on the alternative use of a number of compounds with different modes of action in order to save the longevity of newly developed products. Among pest arthropods, according to the potential for resistance development and a number of documented cases, spider mites (Acari: Tetranychidae), especially species Tetranychus urticae and Panonychus ulmi, as well as certain species of whiteflies and leaf aphids (Homoptra: Aleyrodidae, Aphididae) stand out.In 2002, the company Bayer CropScience introduced spirodiclofen, a tetronic acid derivative and the first cyclic ketoenol, acaricide with a wide spectrum and a novel mode of action -inhibition of acetyl-CoA-carboxylase. Soon after, spiromesifen was introduced, also a derivative of tetronic acid, acaricide and insecticide intended for control of phytophagus mites and whiteflies. Spirotetramat, a tetramic acid derivative, and the third member of the ketoenol group, was recently commercialised as an insecticide efficient against whiteflies, leaf aphids and other harmful Homoptera. In this paper are presented the most significant properties of cyclic ketoenols, aiming at pointing to the possibilities and prospects of their use, but also to potential problems and limitations.

SUMMARYThe mycopesticide Naturalis (based on Beauveria bassiana strain ATCC 74040) and botanical pesticide Kingbo (based on oxymatrine, an alkaloid from Sophora flavescens, a traditional Chinese herb) were tested against the two-spotted spider mite (Tetranychus urticae) on greenhouse vegetables and the European red mite (Panonychus ulmi) on apples. These biopesticide products were applied twice at 5-day interval and concentrations of 0.1% and 0.2%, and their effectiveness was compared to abamectin-based products and the synthetic acaricides acrinathrin and spirodiclofen, applied once at their recommended rates. The mycopesticide Naturalis, applied at 0.1% concentration against T. urticae on cucumber, reduced mite population density by 85-86%, achieving 91-93% efficacy. In a trial on tomato, efficacy reached some 96%, while population density was reduced by 93%. In a field trial on apple, Naturalis demonstrated an increasing and long-lasting effectiveness against the summer population of P. ulmi of nearly 100%, and population reduction was achieved in assessments 30 days after the first treatment. Naturalis applied at a double rate achieved a somewhat better effect but only in the first trial. The botanical pesticide Kingbo, applied at 0.1% concentration, demonstrated very high control efficacy (≥98%) and population density reduction (≥96%) of T. urticae in both trials. A high and long-lasting effectiveness of this bioacaricide was also achieved in a trial on P. ulmi. Its concentration of 0.2% achieved similar effect. The results in these trials indicate that applications of the mycopesticide Naturalis and the botanical pesticide Kingbo can provide effective control of T. urticae on cucumber and tomato grown in greenhouses, as well as P. ulmi on apple.

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