Determination of susceptibility and resistance of some greenhouse populations of Tetranychus urticae Koch to chlorpyrifos (Dursban 4) by the petri dish–Potter tower method

The level of susceptibility of the two-spotted spider mite, Tetranychus urticae Koch, populations collected from greenhouses in Antalya and Isparta regions of Turkey against chlorpyrifos was determined by a petri dish bioassay method. This study consisted of two stages. In the first stage, using a diagnostic dosage (0.026 ml chlorpyrifos in 100 ml distilled water) it was determined whether these populations are resistant or susceptible to chlorpyrifos. Then, different dosages of chlorpyrifos were applied to resistant populations to determine LC₅₀ and LC₉₀ values. Resistant ratios of populations were calculated by dividing the LC₅₀ values of resistant populations by that of a susceptible population of T. urticae strain GSS. The resistance ratio of T. urticae populations collected from greenhouses ranged from 8.00 to 1,774.00. Results show that while three of the populations gathered from the Isparta region, where greenhouse vegetable growing has been increasing since 2000, are susceptible, two of them are only partially resistant to chlorpyrifos. On the other hand, all the two-spotted spider mite populations collected from the Antalya region, the centre of greenhouse vegetable production for many years, were found to be highly resistant to chlorpyrifos.     

Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.     

Acaricidal,repellent and oviposition deterrent activities of <Emphasis Type="Italic">Datura stramonium</Emphasis> L. against adult <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Koch)

The ethanol extracts obtained from both leaf and seed in the Thorn apple (Datura stramonium L.) (Solanaceae) were investigated for acaricidal, repellent and oviposition deterrent properties against adult two-spotted spider mites (Tetranychus urticae Koch) (Acari: Tetranychidae) under laboratory conditions. Leaf and seed extracts, which were applied in 167,250 and 145,750 mg/l concentrations, respectively (using a Petri leaf disc-spray tower method), caused 98 and 25% mortality among spider mite adults after 48 h. The simple logistic regression analysis showed that the independent variable, an increase in the dose of leaf extract was associated with a significant increase in the death rate of T. urticae females, but an increase in the dosage of seed extracts did not have a significant effect. Using probit analysis and estimating the parameters with a confidence limit of 95%, we determined the LC₅₀ values of leaf extract to be 70,593 mg/l. According to Pearson’s χ² test, mites showed the strongest run off to bean leaf surfaces sprayed with both leaf and seed extracts (in sub-lethal doses: <7,500 mg/l and <25,000 mg/l, respectively) and moved towards surfaces that had not been sprayed with extracts. Furthermore, repeated measures ANOVA indicated a significant difference between the number of eggs laid on unsprayed bean leaves compared to bean leaves that were sprayed with leaf and seed extracts at sub-lethal doses, 2,500 and 25,000 mg/l concentrations, respectively. These results suggest that D. stramonium extracts could be used to manage the two-spotted spider mite.     

Laboratory and field evaluations of some botanical pesticides against the cedar leaf moth, <Emphasis Type="Italic">Acleris undulana</Emphasis>

The cedar leaf moth (CLM), Acleris undulana Walsingham, has recently become an important pest in the cedar forests in southwestern Turkey. Control has focussed on the use of synthetic chemical pesticides, with little research having been conducted on alternative control methods. In this study, four botanical pesticides (two commercial neem products, Neemazal-T/S^® and Greeneem^® oil, and two hot water plant extracts, Origanum onites L. and Pimpinella anisum L.) were evaluated for their effects against young (first–second) and older (third–fifth) instar larvae of CLM under laboratory and field conditions. The results of larval dip bioassay in the laboratory showed that all the botanical pesticides tested had significant larvicidal activity against both young and older instars of CLM compared to the water-treated control. Of the botanical pesticides tested, Neemazal was the most larvicidal botanical, causing mortalities ranging from 84 to 100%, the least effective was the P. anisum extract, but at high concentrations this extract still caused significant mortality. Results from field trials also revealed that the botanical pesticides had larvicidal activity against CLM. Neemazal was the most larvicidal botanical, followed by Greeneem oil then by O. onites and finally by P. anisum. Our overall results suggest that all the botanical pesticides tested are promising as larvicides against CLM, and may provide an alternative control method that is more compatible with Integrated Pest Management programs than the use of synthetic chemical pesticides.     

Ovicidal, larvicidal and anti-ovipositional activities of Bifora radians and other plant extracts on the grape berry moth Paralobesia viteana (Clemens)

Methanol extracts of Bifora radians, Arctium lappa, Humulus lupulus and Xanthium strumarium were tested against the North American grape berry moth, Paralobesia viteana in laboratory and greenhouse assays. Egg hatch was reduced by B. radians and X. strumarium extracts, whereas larval mortality was observed in response to B. radians, X. strumarium and A. lappa. Given the high mortality against egg and larval stages of this pest caused by extracts of B. radians, further studies were performed to determine the dose?Cresponse relationships between extracts of this plant and oviposition and egg hatch of P. viteana. There was a significant reduction in egglaying and egg hatch with increasing extract concentration, with 0.1% extracts providing 80% mortality and 1% extracts causing more than 90% control. This study demonstrates the potential of this plant extract for crop protection against a key pest of grapes and suggests that additional crop pests and field tests should be pursued to determine the efficacy of B. radians extracts as a biopesticide.     

Two-spotted spider mite in Cyprus: ineffective acaricides,causes and considerations

Growers of greenhouse roses in Cyprus have recently reported failures of several acaricides against two-spotted spider mite (Tetranychus urticae Koch). To verify the cause of these failures we evaluated the effectiveness of seven acaricides against two rose and two cucumber spider mite populations in the laboratory. The acaricides included in our study represented the most important mode of action groups registered for use in greenhouses on the island. Label rates of all seven acaricides (abamectin, clofentezine, dicofol, fenbutatin oxide, fenazaquin, propargite and milbemectin—a product under registration) caused close to 100% mortality in the cucumber populations, but significantly lower mortality in the two rose populations. Mortality never exceeded 65% in the first rose population and 20% in the second population for any acaricide, suggesting development of resistance. The higher frequency of acaricide applications in roses and the perennial nature of the crop, that sustains genetically similar populations for long periods of time, may have facilitated the development of resistance. Judicious use of newer acaricides with distinct modes of action as they become registered may help control resistant spider mite populations in roses and other ornamental crops. Additionally, adoption of a mode of action labeling scheme of pesticides and training of growers on alternation of products will facilitate long term sustainable spider mite management in Cypriot agriculture.     

Side effect of some fungicides on the mite population in an apple orchard in Croatia

The research into the side effect of fungicides used in the control of the most serious disease in apples (Venturia inaequalis) i. e. the research into the influence of fungicides on the population of phytophagous mites, was carried out at Nedeli??e (North-West Croatia) during 1997 and 1998. The study is related to the population of the mites most present in apple orchards, such as red spider mite (Pananychus ulmi) and other mites (Aculus schlechtendali andTetranychus urticae). Fungicides which are known to be effective against scab, i. e.Venturia inaequalis, and used in fruit production in Croatia, were tested in order to investigate their secondary properties which have not yet been studied. The following fungicides were used: cyprodinil, dodine, dichlofluanid + bitertanol (as tank mix), and kresoxim-methyl. The tests were repeated three times; the application time was determined by monitoring the conditions for infection. The treatments were done curatively, i. e. up to 96 h after the onset of infection conditions. The mite population was estimated by the pressing method, which yielded the average number of mites per leaf. All the results were statistically processed by variance analysis and by Duncan’s Multiple Range Test, and are presented graphically and in tables. The paper also presents graphically the climatic conditions, scab infections and application time. The research over two years have shown a pronounced suppressive effect of dichlofluanid + bitertanol on populations of phytophagous mites, while the other fungicides used in the research had a neutral effect on the mite papulation.     

Influence of the surrounding landscape on the colonization rate of cereal aphids and phytovirus transmission in autumn

Ecological control has often focused on factors enhancing control of pests by their natural enemies, while factors reducing the colonization rate of crops by pests have been comparatively neglected. We present an approach to assess landscape influence on the intensity of wheat colonization by a major crop pest, the aphid Rhopalosiphum padi. We used trays containing wheat seedlings to monitor field colonization by R. padi and barley yellow dwarf viruses’ transmission in two areas in France in autumn. We assessed the influence of landscape components likely affecting aphid colonization, i.e. maize and grasslands as source of migrants on the number of aphids landing per tray, as well as the host plant of origin and the viruliferous potential of migrants. During the survey, maize was the main source of migrants. Virus transmission was detected in a few cases (4 % positive assays). Colonization was increased by the presence of maize, but reduced by the presence of grasslands at the landscape scale considered here (i.e. at a radius of 1000 m). Our study contributes to a better understanding of disease dynamics in agricultural landscapes. By identifying features of the landscape that surrounds fields and affects these dynamics, growers can develop more efficient crop protection strategies relying on habitat manipulation and rational use of pesticides.     

When the ground cover brings guests: is <Emphasis Type="Italic">Anaphothrips obscurus</Emphasis> a friend or a foe for the biological control of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> in clementines?

Biological control of Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementines, can be improved in this crop with the establishment of a ground cover of Festuca arundinacea Schreber (Poaceae). This cover houses an abundant and diverse community of predatory Phytoseiidae mites including Euseius stipulatus (Athias-Henriot), Neoseiulus barkeri Hughes, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot and a dense population of the grass thrips Anaphothrips obscurus Müller (Thysanoptera: Thripidae) throughout the year. The aim of this study was to determine whether the presence of this thrips species could be related to the improvement in the biological control of T. urticae. Therefore, the capacity of the abovementioned phytoseiids to feed and reproduce on A. obscurus and their feeding preferences when T. urticae and A. obscurus were simultaneously offered, were analyzed. The results show that E. stipulatus, N. barkeri and N. californicus have a type II functional response when offered A. obscurus nymphs, whereas P. persimilis barely feeds on this thrips species. Furthermore, N. barkeri and N. californicus can reproduce feeding only on thrips. Regarding prey preference, the Tetranychus spp.-specialist P. persimilis preferably preyed on T. urticae, the generalists N. barkeri and E. stipulatus preferred A. obscurus, and the selective predator of tetranychid mites N. californicus showed no preference. Therefore, we hypothesize that the enhanced biological control of T. urticae observed could be related to A. obscurus becoming an alternative prey for non-specialist phytoseiids, without altering the control exerted by the T. urticae-specialist P. persimilis and likely reducing intraguild predation.     

Studies on phenology and harmfulness of Aceria carvi Nal. (Acari: Eriophyidae) on caraway, Carum carvi L., in the Czech Republic

Caraway (Carum carvi L.) belongs to the traditional crops which have been grown in Bohemia since the end of the 19th century. Depressaria daucella (Denis and Schiffermüller) and Aceria carvi Nal. are two main pests of caraway in the Czech Republic. The latter becomes a serious problem in major caraway-growing areas. So far, no effective method for its control is known. The aim of this paper is to describe the phenology of symptoms of A. carvi infestation and damage caused by this pest. Our observation revealed that although A. carvi overwinters hidden within leaves of young caraway plants, the first symptoms are usually not visible before the start of flowering. Though the initial density of the pest is low, the mite population multiplies during the season when the pest attacks plant tissues and causes development of galls on leaves and flowers. Comparison of healthy plants and plants infested by A. carvi showed that infested plants had significantly more umbels but produced far fewer seeds, and the yield of caraway was thus substantially decreased. Recommendations for crop management methods to suppress the pest are given.Electronic Supplementary Material Supplementary material is available for this article at     

Targeting hidden pests: acaricides against the coconut mite <Emphasis Type="Italic">Aceria guerreronis</Emphasis>

The control of hidden pest species with pesticides depends on the accurate timing of the application to reach the life stages during their only moment of vulnerability, which is when the pests (temporarily) leave their hiding places. A curious case involves the colonization of the coconut perianth, a bract-protected region of the fruit, by the coconut mite Aceria guerreronis. The coconut bracts apparently provide protection against the direct action of acaricides used against the coconut mite. Furthermore, some acaricides target mite eggs and/or immatures in addition to adults, leading to enhanced mortality and/or compromised progeny production, but only if reaching these stages. In this study, we developed methods for assessing the likely protection provided by the coconut bract against the acaricides used for managing the coconut mite. We also assessed the efficacy of the acaricides currently registered for use against this species. Our results support the notion that coconut bracts provide protection to the coconut mite against direct acaricide action. Some acaricides (abamectin and fenpyroximate) were effective only with the removal of the coconut bracts, whereas others (hexythiazox and spirodiclofen) were not effective even with bract removal. Coconut mites sheltered by bracts were protected against the acaricides over time, but the acaricides seemed to induce mite dispersion. In addition, the preventive application of some acaricides reduced the chances of the perianth colonization by the coconut mite. Among the acaricides used, two (hexythiazox and spirodiclofen) are registered as ovicides, but only one (spirodiclofen) acted on eggs, preventing hatching of approximately 40 % of the eggs. The acaricide impacts on coconut mite management are discussed.     

Biological invasion of European tomato crops by Tuta absoluta: ecology, geographic expansion and prospects for biological control

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest of tomato originating from South America. After its initial detection in eastern Spain in 2006, it rapidly invaded various other European countries and spread throughout the Mediterranean basin. If no control measures are taken, then the pest can cause up to 80–100% yield losses in tomato crops in recently invaded areas and may pose a threat to both greenhouse and open-field tomato production. The exceptional speed and extent of T. absoluta invasion have called for studies documenting its biology and ecology, while indicating an urgent need for efficient and sustainable management methods. The development of approaches to manage T. absoluta would be facilitated through a detailed revision of information on this pest in its area of origin. This review combines information on the invasion by T. absoluta, its ecology, and potential management strategies, including data that may help the implementation of efficient biological control programs. These programs, together with a variety of other management tactics, may allow efficient integrated pest management of T. absoluta in Europe and Mediterranean Basin countries.     

Host plant use by two distinct lineages of the tomato red spider mite, <Emphasis Type="Italic">Tetranychus evansi</Emphasis>, differing in their distribution range

The tomato red spider mite, Tetranychus evansi, is an emerging pest of solanaceous crops. Two distinct genetic lineages (I and II) have been identified, lineage I having a much wider geographic distribution than lineage II. This has been attributed to differences in cold hardiness that make lineage I better adapted to colonize the coldest parts of the invaded area. However, other factors such as the ability to exploit different hosts may also be involved. In this work, we compared the performance of the Nice (lineage I) and Perpignan (lineage II) strains of T. evansi on two frequent host plants for this species: black nightshade, Solanum nigrum, and cultivated tomato, S. lycopersicum. In general, Nice strain mites performed better (higher fecundity, lower offspring mortality, bigger egg size and lower percentage of males) than Perpignan strain mites when both: (1) they were reared and tested on the same host plant (S. lycopersicum or S. nigrum); and (2) when shifted from S. nigrum to S. lycopersicum and vice versa. Digestive proteases showed also higher expression in Nice strain mites than in Perpignan strain mites, independently of their plant host, potentially reflecting a more efficient proteolytic digestion of plant proteins. However, no differences in detoxification enzyme (P450, esterases and glutathione S-transferases) activities were found when the two strains were compared. In conclusion, our results demonstrate that Nice strain mites exhibited life history traits leading to higher fitness on two different hosts, which may be related with the higher invasive potential and outbreak risks of mites from lineage I.     

Eucalyptus essential oil as a natural pesticide

Eucalyptus (family Myrtaceae), an Australian native, represented by around 700 species is a genus of tall, evergreen and magnificent trees cultivated world over for its oil, gum, pulp, timber, medicine and aesthetic value. Among the various wood and non-wood products, essential oil found in its foliage is the most important one and finds extensive use in food, perfumery and pharmaceutical industry. In addition, the oil possesses a wide spectrum of biological activity including anti-microbial, fungicidal, insecticidal/insect repellent, herbicidal, acaricidal and nematicidal. The present paper discusses this environmentally benign pest control using eucalyptus oils against bacteria, fungi, insects, nematodes, weeds and mites. The use of eucalyptus oil as a natural pesticide is of immense significance in view of the environmental and toxicological implications of the indiscriminate use of synthetic pesticides and overcoming/reducing the problem of increasing pest resistance.     

Plant-derived essential oils affecting settlement and oviposition of Bemisia tabaci (Genn.) biotype B on tomato

The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is an economically important pest of tomatoes Solanum lycopersicum (L.), causing irregular ripening on fruits and transmitting several plant pathogenic geminiviruses. The management of this pest is commonly based on repetitive spraying with synthetic pesticides, causing serious environmental damages and increase of resistance by insect population. In the present study, essential oils from the leaves of Artemisia camphorata Vill., Ageratum conyzoides L., Foeniculum vulgare Mill., Lippia alba (Mill.) N. E. Br., Plectranthus neochilus Schltr., and Tagetes erecta L. were investigated for their possible repellent and oviposition-deterrent effects against B. tabaci biotype B on tomato. In a multi-choice assay, P. neochilus essential oil was the most active repellent and oviposition deterrent. Essential oils of A. conyzoides and T. erecta significantly deterred the female B. tabaci biotype B from laying eggs on treated tomato leaflets compared with the control. (E)-Caryophyllene (30.67 %) and the monoterpenes α-pinene (15.02 %) and α-thujene (11.70 %) were identified as the major constituents of the essential oil of P. neochilus. Our findings demonstrated the potential of essential oil of P. neochilus and other oils in the reduction of settlement and oviposition of B. tabaci biotype B on tomato.     

Towards a resistance management strategy for Helicoverpa armigera in Bt-cotton in northwestern China: an assessment of potential refuge crops

Transgenic Bt-cotton now dominates the cotton-growing belt in northwestern China where there are few natural plant refuges to act as sources of moths susceptible to Bt toxin. As an initial step towards developing an insect resistance management (IRM) plan for the pest moth, Helicoverpa armigera, on Bt-cotton in this part of China, we assessed the potential of six crops grown in two configurations to act as refuge hosts for susceptible moth production in both broad-acre and small-holder farms. Egg and larval abundance indicated that H. armigera had a preference for chickpea, pigeon pea, and corn, over cotton, sorghum, and benne (sesame). There were no significant differences in egg or larval abundance between plot and strip configurations of these crop hosts. We found that sorghum was not attractive to H. armigera, contrary to the findings in other cotton production areas. Moreover, chickpea, pigeon pea, and corn were determined to be potential refuge hosts based on egg and larval abundance over the growing season. From the adult moth population dynamics in broad-acre and small-holder farms, the efficiency of alternative refuge crops, and local agricultural practices, we recommend that spring corn be grown as a strip crop as part of an IRM strategy to improve the probability of Bt-susceptible moth production and mating with resistant moths in broad-acre farms. In small-holder farms where current agricultural practices are entrenched, wheat and summer corn should be evaluated as refuge crops in the future.     

Effect of soybean cultivar on life history parameters of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch (Acari: Tetranychidae)

The two-spotted spider mite, Tetranychus urticae Koch, is a very polyphagous pest with a worldwide distribution. In order to appraise population growth parameters of this pest, samples of two-spotted spider mites were taken from soybean (Glycine max) fields of Moghan region, Iran in June 2007 and are reared on bean plants var. Derakhshan (Phaseolus vulgaris) in a growth chamber. The life table parameters of this pest were calculated on three commercial soybean cultivars (Zane, Hach, and L17) and one hybrid (Hob × Will) at 25 ± 1°C, 60 ± 10%RH, and 16 h photophase. The developmental times of immature stages varied from 9.69 on Hach to 9.82 days on L17, whereas the immature survival was 57–79% on Hach and Hob × Will, respectively. On average, there were 65.5, 40.8, 38.8 and 34 eggs produced per female on L17, Hach, Hob × Will and Zane, respectively. The intrinsic rate of natural increase (r _m ) for T. urticae on Hob × Will was the highest, whereas the values for r _m ranged from 0.211 (females/female/day) on Zane to 0.292 on Hob × Will. Also, jackknife values of other life table parameters such as net reproductive rate (R ₀), generation times (T), doubling time (DT), and finite rate of increase (λ) on these cultivars were estimated. Overall, the two-spotted spider mite indicated a better performance on Hob × Will than on the other soybean cultivars.     

Zur Wirkung von Temperatur und Photoperiode auf die Entwicklung,Ernährung und Eiablage der Raubmilbe Amblyseius swirskii Ath.-Henr. (Acari,Gamasida, Phytoseiidae)

Amblyseius swirskii was reared on immature stages ofTetranychus urticae Koch, under 4 temperature and 3 photoperiod regimes. The raise of temperature produced more rapid development and reduced the adult longevity. The mite feeding capacity and fecundity were positively correlated with temperature. At a photoperiod of 16 h the predator developed quicker but it introduced a considerably lower prey consumption and fecundity.     

Attraction of <Emphasis Type="Italic">Lygus rugulipennis</Emphasis> and <Emphasis Type="Italic">Adelphocoris lineolatus</Emphasis> to synthetic floral odour compounds in field experiments in Hungary

Field experiments were carried out to ascertain whether synthetic floral odour compounds were attractive for two pest bug species. The European tarnished plant bug (Lygus rugulipennis Poppius) has been reported to damage various crops (e.g. strawberry, sugarbeet, alfalfa, cucumber), and the alfalfa plant bug (Adelphocoris lineolatus (Goeze)) is considered as a pest of alfalfa and Bt-cotton. In our field tests, traps baited with phenylacetaldehyde caught significantly more L. rugulipennis than unbaited traps. In addition, A. lineolatus was also attracted to phenylacetaldehyde-baited traps. When testing other, EAG active compounds, (E)-cinnamaldehyde attracted A. lineolatus as well. This compound was also attractive for L. rugulipennis, however, to a lesser extent than phenylacetaldehyde. When the two compounds were presented in combination, no synergistic or inhibitory effect was detected in either species. By attracting both sexes of both species, these new attractants may prove to be useful and provide the basis for further development of new lures for agricultural use.     

Zur Prüfung der Nebenwirkung von Pflanzenschutzmitteln auf Nutzarthropoden an der lebenden Pflanze Die Prüfung mit Phygadeuon trichops Thomson (Ichneumonidae)

50 pesticides have been tested for side effects against the beneficial insectPhygadeuon trichops Thomson (Ichneumonidae) using a living plant method. In this connection on the one hand among the insecticides compounds could have been found, which are harmless to this insect and therefore suitable for employment in programs for integrated pest control, on the other hand compounds have been found among the herbicides and fungicides harming these beneficial insects. These results are compared with findings obtained bt the method using glass cages. For about the half of the comparable instances the tests in the glass cages turned out to be to hard, that means the compounds are acting more harmfull than during the test on living plants.