An acarine predator-prey population infesting roses

When Phytoseiulus persimilis was reared with Tetranychus urticae, infesting roses propagated in a greenhouse at controlled daily temperatures of 24°C (12 hrs) and 18°C (12 hrs), prey numbers fluctuated with peaks of increasing amplitude. Differential dispersal of prey and predator species was one factor contributing to the inability of the natural enemy to control the pest population.     

Mating and prey stage affecting life history,reproduction and life table of the predacious mite Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae)

Abstract

Two factors were examined to determine their effect on the life history, reproduction and life table parameters in the predacious mite Phytoseiulus macropilis (Banks) in the laboratory. The factors studied included multiple mating and various prey stages of Tetranychus urticae Koch. When females fed on mixed actives (protonymphs and deutonymphs) of T. urticae, the fecundity of females mated more than once was 1.7 times higher than in females mated only once, also oviposition period and adult longevity was longer. The adult longevity and life span of P. macropilis were similar when fed on mixed actives, eggs (0 – 24-h-old) and (0 – 48-h-old) of T. urticae, while both periods were increased and reproduction was higher when fed on older eggs (72 – 96-h-old) of T. urticae. The total number of eggs deposited by females was significantly higher on eggs of (various ages) than on mixed actives of T. urticae. Life table parameters showed that a diet of (72 – 96-h-old) eggs of T. urticae provided the longest generation time (11.066 days) and female longevity (33.54 days) as well as the highest intrinsic rate of natural increase (rm = 0.36755) and greatest total fecundity which resulted in the highest net reproductive rate (Ro = 58.4136) value. The adult female consumed daily an average of 6.8 mixed actives of T. urticae during its life cycle, while it was increased to 13.6 during the oviposition period. The daily (72 – 96-h-old) eggs of T. urticae consumed by female P. macropilis during its life cycle and adult longevity was significantly higher than that recorded on either (0 – 24-h-old) or (0 – 48-h-old) eggs of T. urticae.     

Plant protection in sustainable systems of agriculture

Abstract

A comprehensive evaluation of 13 plant essential oils namely: caraway, chenopodium, cinnamon, clove, eucalyptus, garlic, geranium, lemon, matrecary, peppermint, rose, rosemary and thyme and 14 of their monoterpenoidal constituents: borneol, camphor, carvacrol, carveol, carvone (R and S), chlorothymol, cineol, cinnamaldehyde, citronellol, eugenol, geraneol, menthol, and thymol was investigated for their antibacterial activity against the two phytopathogenic bacteria, Agrobacterium tumefaciens and Erwinia carotovora var carotovora. Trials for improving the antibacterial activity by either structure modification or mixing with the three synergists: piperonyl butoxide, Triton X-100 and Tween 20 were achieved. New N-methyl carbamate derivatives based on monoterpenoids were introduced. Cinnamon, clove, chenopodium, caraway, rosemary and thyme oils proved to possess good antibacterial activity. Thymol, chlorothymol, and carvacrol were potent against the tested bacteria and quite close to the effect of the standard. Conversion of menthol into its carbamate derivative gave good enhancement in the bactericidal activity at all concentrations compared to menthol itself. Also, the carbamate derivatives of β-citronellol and borneol improved the bactericidal activity against E. carotovora, but decreased it against A. tumefaciens. Synergistic antibacterial activity of the tested monoterpenoids was observed when combined with each of the three synergists particularly with Triton X-100.     

Integrated pest management of two-spotted mite Tetranychus urticae on greenhouse roses using petroleum spray oil and the predatory mite Phytoseiulus persimilis

From 1995 to 1999, four experiments were conducted on greenhouse roses to assess the effectiveness of the nC24 petroleum spray oil (PSO), D-C-Tron Plus, against two-spotted mite, Tetranychus urticae Koch (Acarina: Tetranychidae), and to determine how the oil could be most efficiently and effectively used in combination with the predatory mite Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) in an integrated pest management program. The results showed that 0.5% PSO applied fortnightly to roses gave excellent protection from T. urticae infestation when the mite population was not already established. However, PSO applied after roses were infested with T. urticae above the economic threshold only stabilised populations without reducing them below that threshold. Populations of P. persimilis in the upper and lower canopies were unchanged after two sprays of PSO at 7-day intervals, and application of PSO to the upper canopy was as effective in controlling T. urticae in the presence of P. persimilis as spraying the entire plant. Combining PSO with P. persimilis gave better control of T. urticae than using P. persimilis alone. The most cost-effective use of PSO in the presence of P. persimilis is, therefore, to apply spray only to the upper canopy. This will not affect control of powdery mildew with PSO. Comparison of a control program for T. urticae based on the monitored use of synthetic miticides with that based on calendar application of PSO revealed that both gave equally effective control. The benefits of combining PSO and P. persimilis in an integrated pest management program for T. urticae on roses over a program based on synthetic fungicides are discussed.     

Various effects of ethanolic extract of Mentha pulegium on the two-spotted spider mite,Tetranychus urticae (Tetranychidae)

Ethanolic extract of Mentha pulegium was evaluated against the adults of important arthropod pest species, the two-spotted spider mite, Tetranychus urticae. Potential acaricidal impact of plant was determined by contact application. Phytotoxicity was recorded after 24 h. The value of LC₅₀ was 59,149 mg L^?1. Also, LT₅₀ values were 27.42, 25.56 and 19.79 h for 35,000, 50,000 and 100,000 mg L^?1, respectively. Also, results showed that this ethanolic extract had impact on repellency of T. urticae. All of the tested concentrations were similar in the repellency test. On the other hand, the used concentrations (1000, 4000, 6000 and 8000 mg L^?1) affected on the oviposition of mite females. These extract doses significantly decreased the egg laying on the treated surface. The current study indicated that this ethanolic extract can be used as a safe acaricide on T. urticae.     

Preliminary evaluation of <Emphasis Type="Italic">Cladosporium cladosporioides</Emphasis> (Fresen.) de Vries in laboratory conditions,as a potential candidate for biocontrol of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> Koch

A survey for natural entomopathogenic fungi of two spotted spider mite (Tetranychus urticae) adults was made in Erzurum, Turkey, during the period 2006. Tetranychus urticae (65.8%) infected with a strain of the fungus Cladosporium cladosporioides were found. Thirteen isolates of C. cladosporioides were assessed against T. urticae, in a single dose (8 × 10⁶ conidia ml ⁻¹), laboratory bioassay on bean leaflets. The total mortality percentage caused by C. cladosporioides isolates varied from 50.95 to 74.76% and LT₅₀ values ranged from 2.34 to 3.90 days. The results revealed that isolates of C. cladosporioides were effective against two spotted spider mite. This is the first record of natural infection of T. urticae by C. cladosporioides.     

Functional response ofAllothrombium pulvinum deutonymphs (Acari: Trombidiidae) on two-spotted spider mites (Acari: Tetranychidae)

Functional responses of deutonymphs of the predatory mite,Allothrombium pulvinum Ewing, on eggs and adult females of two-spotted spider mite,Tetranychus urticae Koch, were determined in the laboratory. Predation experiments were conducted on lima bean leaf discs over a 24-h period at 25±2°C, 30–50% RH and 24L: 0D photoperiod. Prey densities ranged from 10 to 120T. urticae eggs per disc or 2 to 32 adult females per disc.Allothrombium pulvinum deutonymphs were more effective againstT. urticae eggs than its adult females. The role ofA. pulvinum deutonymphs in integrated and biological pest control is discussed.     

Adaptation of acaricide stress facilitates Tetranychus urticae expanding against Tetranychus cinnabarinus in China

The two‐spotted spider mite, Tetranychus urticae, and the carmine spider mite, Tetranychus cinnabarinus, are invasive and native species in China, respectively. Compared with T. cinnabarinus, T. urticae has expanded into most parts of China and has become the dominant species of spider mite since 1983, when it was first reported in China. However, the mechanism of the demographic conversion has not been illuminated. In this study, one T. urticae field population and one T. cinnabarinus field population were isolated from the same plant in the same field, and the toxicological characteristics were compared between these two species. Laboratory bioassays demonstrated that T. urticae was more tolerant to commonly used acaricides than T. cinnabarinus. The activities of detoxification enzymes were significantly greater in T. urticae, and the fold changes of enzymes activities in T. urticae were also greater following exposure to acaricides. Furthermore, more metabolism‐related genes were upregulated at a basal level, and more genes were induced in T. urticae following exposure to acaricides. The comparison of proteins and genes between both species led credence to the hypothesis that T. urticae was more resistant to acaricides, which was the reason explaining the expansion of invasive T. urticae against native T. cinnabarinus. Laboratory simulation experiments demonstrated that following the application of acaricides, the composition of a mixed T. urticae/T. cinnabarinus population would change from a T. cinnabarinus‐dominant to a T. urticae‐dominant population. This study not only reveals that T. urticae possesses stronger detoxification capacity than its sibling species T. cinnabarinus, which facilitated its persistent expansion in China, but also points to the need to accurately identify Tetranychus species and to develop species‐specific management strategies for these pests.     

Predation by Allothrombium pulvinum on the spider mites Tetranychus urticae and Amphitetranychus viennensis: Predation Rate, Prey Preference and Functional Response

The deutonymphs of Allothrombium pulvinum Ewing (Acari: Trombidiidae) are among the most important natural enemies of spider mites in North, North East and West Iran. In this study, maximum predation rate and preference experiments were conducted with A. pulvinum deutonymphs on apple leaf discs, to determine their preference for either of two spider mite species: Amphitetranychus viennensis (Zacher) and Tetranychus urticae Koch (Acari: Tetranychidae). Maximum predation rate tests showed that the predatory mite consumed more eggs and females of T. urticae than of A. viennensis. Furthermore, the Manly’s preference index for eggs and females of T. urticae confirmed that T. urticae were the preferred prey. The functional response of A. pulvinum deutonymphs on females of T. urticae was examined over a 24-h period. Predation of A. pulvinum deutonymphs presented with females of T. urticae followed a type III functional response. Estimated handling time for the predatory mites was 4.51 h and attack coefficient b, which describes the changes in attack rate with prey densities in a type III functional response, was 0.021.     

Lethal and sublethal effects of spiromesifen,spirotetramat and spirodiclofen on Tetranychus urticae Koch (Acari: Tetranychidae)

Lethal and sublethal effects of spirotetramat, spiromesifen and spirodiclofen were assessed on Tetranychus urticae Koch. Leaf disc bioassay was used in all experiments. In this study, toxicity of these compounds was tested on T. urticae eggs and adults. Ovicidal activity was observed in all of the compounds tested, but only spirodiclofen was considerably effective against adult mites. Up to 24?h-old adult females were placed on leaf discs treated with sublethal concentrations (LC₁₀ or LC₂₅). Twenty-four hours after exposure to treated discs, 20 females showing no visible symptoms of poisoning were transferred to untreated leaf discs. The leaf discs were changed daily for up to five days. The number of eggs laid during this period was recorded. The survival rate, total number of laid eggs per female and egg hatching rate were calculated. All above-mentioned parameters were slightly lower in treated females compared with controls.     

Lethal activity of beauvericin,a Beauveria bassiana mycotoxin,against the two‐spotted spider mites,Tetranychus urticae Koch

The entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin is known to produce a broad range of secondary metabolites. Beauvericin, a cyclic hexadepsipeptide, is the best known mycotoxin produced by B. bassiana; however, reports discussing the insecticidal activity of beauvericin per se are limited. In this study, we assessed the lethal activity of beauvericin against Tetranychus urticae Koch (Acarina: Tetranychidae). In addition, screening for suitable application of the mycotoxin against T. urticae on greenhouse strawberries is discussed. Beauvericin was able to control successfully T. urticae where concentrations of 10, 100 and 1,000 µg/g recorded mortalities of 84%, 100% and 100%, respectively, against motile stages. Furthermore, beauvericin inhibited egg hatching up to 83.3%, 69.3% and 53.3%, respectively, using the same concentrations under laboratory conditions. Under greenhouse conditions, the efficacy recorded was 52.6%, 85.7%, 72.4% and 72.4% at 1, 3, 7 and 10 days post‐inoculation, respectively. Beauvericin was efficacious under greenhouse conditions since the application increased strawberry yields while showing no phytotoxicity and ecotoxicological risk. Resistance to beauvericin was not detected initially at the unselected strain of T. urticae. Yet, the laboratory selection of populations of T. urticae exposed to beauvericin resulted in relatively resistant T. urticae strain that displayed no cross‐resistance to cyflumetofen and bifenazate. The acaricidal activity of beauvericin documented in this study would increase the efficacy of integrated pest management strategies.     

Lipid Constituents of Callus Tissues of Mentha spicata

A callus tissue culture was established from leaves and stems of Mentha spicata L. Lipid constituents isolated from callus tissues were composed of fatty acids, fatty acid methyl esters, triglycerides, squalene, stigrnasterol, sitosterol, oleanolic acid (1), ursolic acid (2) and pomolic acid (3). These liquid constituents did not contain monoterpenoids.     

Resistance to organophosphates in red spider mite, Tetranychus urticae, from English hop gardens

Two strains of Tetranychus urticae, collected in 1969 from hops in Kent (strain RK) and Wisbech, Cambridgeshire (RW), showed a similar pattern of resistance to organophosphates, high to parathion (> 100 ×), low to azinphos-ethyl (7 ×) and intermediate to demeton-S-methyl (21–27 ×); they were both fully susceptible to tetradifon, dicofol and formetanate. RK showed greatei than 50 × resistance to fourteen other organophosphates; exceptions were azinphos-methyl (11 ×), phosphamidon (21 ×) and methidathion (31 ×). Resistance in RK was shown to be controlled by a single major gene, incompletely dominant with parathion but nearer to intermediate in expression to demeton-S-methyl and azinphos-ethyl. A test for allelism showed that the major genes for O.P. resistance in RK and the Dutch strain Baardse reside at the same locus or are closely linked. The results are compared with other work on T. urticae and on Panonychus ulmi.     

Influence of Temperature on Virulence of Fungal Isolates of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> and <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to the Two-Spotted Spider Mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C. The lethal time to 50% mortality (LT₅₀) and lethal time to 90% mortality (LT₉₀) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates at 30 and 35°C; however, significant differences were observed at 20 and 25°C.     

Bioproduction of an extract from Penicillium funiculosum Thom with activity against Ceratitis capitata and Tetranychus urticae

The bioproduction conditions of a crude extract from a strain of Penicillium funiculosum Thom, which shows activity against Ceratitis capitata and Tetranychus urticae, have been optimized. The efficacy degree was 95% (C. capitata) and 100% (T. urticae), according to Abbot. This is the first report on the pesticide activity of an extract from P. funiculosum against these species. The best yields were obtained when P. funiculosum was grown in Raulin-Thom medium at pH 6.5 with sucrose candy as the carbon source and ammonium sulphate and phosphate as the nitrogen source. Other favourable conditions were static cultures, at 28°C, and in the dark. Correspondence to: M. Jiménez     

Integrated control of the most damaging pests of peach trees in Greece

In this study, the integrated management of Myzus persicae, Adoxophytes orana, Anarsia lineatella, Grapholita molesta, Panonychus ulmi and Tetranychus urticae was evaluated. The results showed that the population of Myzus persica on integrated systems was significantly lower than untreated control and higher than conventional systems. The population of P. ulmi and T. urticae was relatively low ( < 2 per leaf) in all treatments. Damage to fruit caused from A. orana and A. lineatella were significantly higher on untreated control than integrated or conventional systems. The results also showed that the damages caused from G. molesta were low in both conventional and integrated systems. In contrast, this insect caused significantly higher damage on untreated fruit.     

Host plant-mediated interactions between Tetranychus urticae and Eotetranychus carpini borealis (Acari: Tetranychidae)

Competitive interactions between Tetranychus urticae and Eotetranychus carpini borealis were investigated under laboratory and greenhouse conditions. When placed first to colonize red raspberry leaves, T. urticae caused extinction of E. carpini borealis populations. E. carpini borealis had detrimental effects on T. urticae but did not cause T. urticae population extinction. The area used by E. carpini borealis for egg deposition decreased with an increase in the number of T. urticae eggs. Red raspberry showed an induced response to T. urticae and E. carpini borealis feeding after two weeks of infestation. Population growth of each species was reduced on plants that were previously infested by conspecifics but inducible response by one species had no effects on the other species.     

Predation-related odours reduce oviposition in a herbivorous mite

When adult females of the herbivorous mite, Tetranychus urticae, were exposed to the predatory mite, Phytoseiulus persimilis, they laid fewer eggs than females that had not been exposed to P. persimilis when transferred onto a new leaf patch. However, when T. urticae females were exposed to either products of P. persimilis or artificially damaged conspecific eggs on a leaf patch, the number of T. urticae eggs on a new leaf patch did not differ significantly from the control. The reduced oviposition was neither due to the feeding activity on the leaf patch with P. persimilis nor to that on the new leaf patch. There was also no significant difference between the number of T. urticae eggs produced on a new leaf patch following exposure to the odours of a neighbouring leaf patch where there had previously been either P. persimilis or T. urticae adults. However, female T. urticae that had been exposed to odours from neighbouring leaf patches on which both T. urticae and P. persimilis had been placed produced significantly fewer eggs on a new leaf patch than those that had not been exposed to such odours. Neither odours from neighbouring intact leaf patches on which T. urticae eggs were preyed on by P. persimilis, nor odours from a neighbouring Parafilm patch on which T. urticae was preyed on by P. persimilis affected the oviposition of T. urticae. These data suggest that the presence of T. urticae, P. persimilis and a leaf patch are needed for the emission of odours to reduce oviposition in T. urticae.     

Fumigant activity of essential oils and their components from Eucalyptus codonocarpa and E. dives against Tetranychus urticae (Acari: Tetranychidae) at three temperatures

Essential oils derived from eighteen species of the Myrtaceae family native to Australia, and major constituents of two oils selected from these oils were tested for their fumigant activity against adult females and eggs of Tetranychus urticae Koch (Acari: Tetranychidae) at 5, 15 and 25°C. Essential oils of Eucalyptus codonocarpa and Eucalyptus dives showed the highest fumigant activity against female adults at 10 μl/l at 15 and 25°C. Among major constituents of the two essential oils, piperitone was the most effective against female adults, followed by terpinene‐4‐ol at 10 μl/l at all three temperatures. The two essential oils and these two constituents lowered egg hatchability at 10 μl/l at 25°C. Our results suggest that piperitone should be further investigated as a potential fumigant against T. urticae.     

Pre-adult development of Phytoseiulus persimilis on diets of Tetranychus urticae and Tetranychus lintearius: implications for the biological control of Ulex europaeus

Predation by the phytoseiid mite, Phytoseiulus persimilis, is considered a major threat to the effectiveness of biological control of gorse, Ulex europaeus, using Tetranychus lintearius. To assess this threat and to determine if the impact of P. persimilis on T. lintearius populations is comparable to its impact on T. urticae populations, its development and predator : prey generation time ratios were assessed. The pre-adult mortality and development time of two populations of P. persimilis fed on two diets, T. urticae and T. lintearius, were determined at two temperatures, 14 and 24°C. There were no significant differences in either mortality or development time between the two populations of P. persimilis at these temperatures. There is therefore no evidence that the two tested populations of P. persimilis are behaving as different strains. Similarly, diet had no significant effect on either mortality or development time at these temperatures. At 14°C the mortality of P. persimilis was significantly higher and development was significantly longer than at 24°C. Using pre-adult development as a surrogate for generation times, predator : prey generation time ratios were calculated between P. persimilis and both T. urticae and T. lintearius using data from this and other studies. The predator : prey generation time ratios between P. persimilis and T. lintearius were lower than those between P. persimilis and T. urticae. These results indicate that the impact of P. persimilis on T. lintearius populations is likely to be comparable to its impact on T. urticae populations. This provides further evidence that predation by P. persimilis is having a deleterious effect on T. lintearius populations and therefore reducing its effectiveness as a biological control agent for gorse.