A new monitoring approach for the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) in hop culture

Journal of Plant Diseases and Protection - The two-spotted spider mite, Tetranychus urticae Koch, is a major pest in hops with world-wide economic importance. According to official guidelines, the...     

Acaricidal activities of Santolina africana and Hertia cheirifolia essential oils against the two-spotted spider mite (Tetranychus urticae)

BACKGROUND: Many plant essential oils show a broad spectrum of activity against pests. This study investigated the effects of two essential oils on Tetranychus urticae, one of the most serious pests in the world. RESULTS: The chemical composition of the two oils was characterised by GC‐MS. The most abundant component in the Santolina africana (Jord. & Fourr) oil was terpinen‐4‐ol (54.96%), while thymol (61%) was prevalent in the Hertia cheirifolia (L.) oil. Mortality and fecundity were measured upon treatment with oil concentrations ranging from 0.07 to 6.75 mg L^?1 with a Potter spray tower. Mite mortality increased with oil concentration, with LC₅₀ values of 2.35 mg L^?1 for S. africana and 3.43 mg L^?1 for H. cheirifolia respectively. For both oils, a reduction in fecundity was observed at concentrations of 0.07, 0.09 and 0.29 mg L^?1. Artificial blends of constituents of oils were also prepared and tested with individual constituents missing from the mixture. The results showed that the presence of all constituents was necessary to equal the toxicity of the two natural oils. CONCLUSION: S. africana and H. cheirifolia oils can provide valuable acaricide activity with significantly lower LC₅₀ values. Thus, these oils cause important mortality and reduce the number of eggs laid by females. Copyright © 2012 Society of Chemical Industry     

Synergistic effect of Beauveria bassiana and spirodiclofen on the two-spotted spider mite (Tetranychus urticae)

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pests in agriculture. Due to its short life cycle and high reproductive rate, this pest has become resistant to most acaricides. Therefore, finding alternative control strategies for this damaging pest is necessary. Application of microbiological agents with minimum concentrations of acaricides is a very suitable tactic in integrated pest management. In the present study, lethal effects of a chemical acaricide – spirodiclofen, and an Iranian strain of the entomopathogenic fungus Beauveria bassiana, were evaluated on different life stages of the two-spotted spider mite on two host plants, bean and cucumber. In the next step, compatibility of acaricide with the fungus was studied regarding conidial germination and vegetative growth of the fungus in the presence of different concentrations of the acaricide. Finally, the acaricide at rates of LC₂₅ with the fungus at LC₅₀ were sprayed on adult female mites. The results showed that immature stages of T. urticae were more susceptible to the acaricide whereas the adults were more susceptible to the fungus. Also, mites reared on cucumber were significantly more susceptible to the acaricide and fungus than those reared on bean. Spirodiclofen and the fungus had a synergistic effect; percentage of mortality for fungus infection was 48.6% and 53.5% on bean and cucumber, respectively, while it was 80.6% on bean and 84.5% on cucumber when the mite was sprayed with both the fungus and the acaricide.     

Fitness costs associated with milbemectin resistance in the two-spotted spider mite Tetranychus urticae

The two-spotted spider mite Tetranychus urticae Koch is one of the most important pests of a wide range of crops worldwide. Its control is still largely based on the use of acaricides. However, due to its short life-cycle, high fecundity and arrhenotokous reproduction, it is able to develop resistance to these compounds very rapidly. Preliminary studies for milbemectin resistance in T. urticae showed that, under laboratory conditions, such resistance was unstable in the absence of a selection pressure. The aim of this study was to evaluate the possible fitness costs associated with milbemectin resistance in T. urticae. Comparison of biological traits between resistant and susceptible strains indicated the occurrence of fitness costs associated with milbemectin resistance. The resistant strain showed a longer juvenile development period for females, lower fecundity and a higher proportion of males among the progeny. The figures for net reproductive rate (R ₀), intrinsic rate of natural increase (r _m) and finite rate of increase (λ) were higher in the susceptible strain. The instability of milbemectin resistance can be exploited in resistance management programmes.     

Esterase-mediated bifenthrin resistance in a multiresistant strain of the two-spotted spider mite, Tetranychus urticae

A field-collected multiresistant strain of Tetranychus urticae Koch exhibiting high resistance to bifenthrin was investigated in comparison with a susceptible laboratory strain. The esterase inhibitor S,S,S-tributyl-phosphorotrithioate (DEF) was able strongly to synergise bifenthrin toxicity in the resistant strain. Optimal conditions for determining esterase activities in T. urticae were determined, and a higher esterase activity towards several artificial substrates was found in this resistant strain, which had a preference for hydrolysing 4-nitrophenyl butyrate. Bifenthrin was able to bind the active centres of T. urticae esterases in vitro, as was determined after competition experiments by a Dixon plot, revealing a higher affinity of bifenthrin in the resistant strain. Bifenthrin-hydrolysing activity in the resistant and susceptible strains was examined in vitro and quantified with gas chromatography. A 7.2-fold higher metabolising rate was found in the resistant strain.     

Resistance to bifenthrin and resistance mechanisms of different strains of the two-spotted spider mite (Tetranychus urticae) from Turkey

Nine different strains of the two-spotted spider miteTetranychus urticae Koch (Acari: Tetranychidae) were collected on cotton from Adana, Antalya, Izmir, Manisa and Urfa in Turkey. Their responses to bifenthrin were investigated using conventional bioassay and biochemical assays. LC₅₀ and LC₉₀ values of bifenthrin were determined for all strains by using a residual bioassay with a petri dish-spray tower. Resistance ratios were determined by comparing the samples with a standard susceptible strain, GSS. The resistance ratios of the strains ranged from <1 to 669-fold (at LC₅₀). Of the investigated field strains, only three (two from Adana and one from Urfa) were resistant to bifenthrin. There was a correlation between esterase enzyme activity and bifenthrin resistance according to polyacrylamide gel electrophoresis and microtiter plate assays in the three resistant strains. http://www.phytoparasitica.org posting May 17, 2005.     

Effects of far-red light on tritrophic interactions between the two-spotted spider mite (Tetranychus urticae) and the predatory mite Phytoseiulus persimilis on tomato

BACKGROUND

The use of light-emitting diode (LED) lights in horticulture allows growers to adjust the light spectrum to optimize crop production and quality. However, changes in light quality can also influence plant–arthropod interactions, with possible consequences for pest management. The addition of far-red light has been shown to interfere with plant immunity, thereby increasing plant susceptibility to biotic stress and increasing pest performance. Far-red light also influences plant emission of volatile organic compounds (VOCs) and might thus influence tritrophic interactions with biological control agents. We investigated how far-red light influences the VOC-mediated attraction of the predatory mite Phytoseiulus persimilis to tomato plants infested with Tetranychus urticae, and its ability to control T. urticae populations.

RESULTS

Far-red light significantly influences herbivore-induced VOC emissions of tomato plants, characterized by a change in relative abundance of terpenoids, but this did not influence the attraction of P. persimilis to herbivore-induced plants. Supplemental far-red light led to an increased population growth of T. urticae and increased numbers of P. persimilis. This resulted in a stronger suppression of T. urticae populations under supplemental far-red light, to similar T. urticae numbers as in control conditions without supplemental far-red light.

CONCLUSION

We conclude that supplemental far-red light can change herbivore-induced VOC emissions but does not interfere with the attraction of the predator P. persimilis. Moreover, far-red light stimulates biological control of spider mites in glasshouse tomatoes due to increased population build-up of the biocontrol agent. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Biology and seasonal abundance of the two-spotted spider mite, Tetranychus urticae, on orchids and rose

Biology of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) was studied on five orchids and one rose species under laboratory conditions. The duration of developmental stages of this mite was the shortest on rose (7.17 ± 0.20 days) followed by Cymbidium (10.49 ± 1.50 days), Oncidium (11.60 ± 1.32 days), Dendrobium (12.67 ± 0.21 days), Phalaenopsis (14.47 ± 1.21 days) and Coelogyne (17.10 ± 1.29 days). The number of eggs/female laid was maximum on rose, whereas the minimum was on Phalaenopsis under the most suitable temperature (26 ± 2°C) and relative humidity (65 ± 5%) conditions. The five orchid farms (three conventionally sprayed and two unsprayed) in the northeastern region of India were surveyed during 2009 and 2010 for mite incidence. Twenty-three species and 11 hybrids of orchids were encountered as the most preferred host, 12 species as moderately preferred, and 28 species and one hybrid were found to be the least preferred orchid host for T. urticae. The mite’s incidence was recorded on orchids all year round, indicative of overlapping generations; however, two distinct population peaks were recorded during April and May. Subsequently its population declined at the start of the rainy season and remained at extremely low levels in the winter. Maximum and minimum temperatures had a significant positive correlation with mite incidence; daylight had a non-significant positive correlation; and rainfall and relative humidity had non-significant negative correlations with mite incidence. The results are discussed in relation to the most susceptible stage on orchids and suitable management practices for the two-spotted spider mite in India.     

Incidence and inheritance of resistance to METI-acaricides in European strains of the two-spotted spider mite (Tetranychus urticae) (Acari: Tetranychidae)

A strain of Tetranychus urticae (Koch; Acari: Tetranychidae), collected from hops (Humulus humuli L; Cannabaceae) in England with a short history of tebufenpyrad use, exhibited resistance to four METI (mitochondrial electron transport inhibitor)-acaricides; tebufenpyrad, pyridaben, fenazaquin and fenpyroximate. Resistance factors for these compounds in a microimmersion assay were 46, 346, 168 and 77 respectively, and corresponded to those exhibited by a Japanese METI-acaricide-resistant reference strain. Levels of resistance remained stable without further selection, and selection with tebufenpyrad did not increase them. The UK strain was also resistant (c 6-fold) to bifenthrin. Crosses of homozygous, diploid females with hemizygous, haploid males showed that, in the UK strain, METI-acaricide resistance was paternally and maternally inherited, and was an incompletely dominant trait. Another tebufenpyrad-resistant strain from the UK, originating from a chrysanthemum nursery (Chrysanthemum foeniculaceum Giseke; Asteraceae) was collected eight months later at a site c 210 km distant from the first. These are the first published incidences of METI-acaricide resistance in Europe and implications for the future use of these compounds are discussed.     

New developments in insecticide resistance in the glasshouse whitefly (Trialeurodes vaporariorum) and the two-spotted spider mite (Tetranychus urticae) in the UK

A recent survey of insecticide resistance in two of the most problematic pests in UK glasshouses revealed some new developments. At least some individuals in all UK samples of Trialeurodes vaporariorum that were tested resisted the insect growth regulator (IGR) buprofezin. The most strongly resistant strains were unaffected by the field application rate of this compound, and even samples from populations that had never been exposed to buprofezin contained individuals that survived the highest concentration applied (10,000 mg litre-1). The field rate of buprofezin was shown to select for resistance through vapour action alone. The benzophenylurea teflubenzuron, an unrelated IGR, was cross-resisted by buprofezin-resistant individuals. There was no evidence of resistance to imidacloprid, but all T vaporariorum strains tested, regardless of origin, exhibited a high innate tolerance to nicotine, when compared with another whitefly species, Bemisia tabaci. Marked resistance to fenbutatin oxide and tebufenpyrad was found in single glasshouse populations of Tetranychus urticae, but these compounds and abamectin appeared to remain highly effective against all other strains collected.     

Biological control of two-spotted spider mite (Tetranychus urticae) by Phytoseiulus persimilis on strawberries grown in walk-in' plastic tunnels, and a simplified method of spider mite population assessment

During 1980 and 1981, a large-scale trial of the biological control of two-spotted spider mite ( Tetranychus urticae Koch) on protected strawbenies, using the predatory'mite Phytoseiulus persimilis Athias-Henriot, was done in 52 'walk-in' plastic tunnels on a commercial nursery in southern England. Introductions of predatory mites in March or early April at a rate of one per plant were consistently successful. In 1980, when predators had not been introduced the previous year (so enabling large numbers of spider mites to overwinter) peak mite populations were large, causing slight foliar damage in some tunnels before control was achieved. In 1981, only a small residual population of spider mites had survived from the previous year and peak numbers were small; the crop appeared healthy and there was no visible damage by mites. For jdequate control, reintroduction of predators was found to be necessary when CTops were replanted in the summer following soil cultivation and sterilization with methyl bromide.
A population assessment method for two-spotted spider mite based on counting aggregations of the mites was devised. The mean number of spider mites (all stages) per leaf was found to be approximately the same as the number of leaves with five or more mites present in a 25-leaf sample.     

Synthesis and juvenile hormone activities of some new ether derivatives of hydroquinone

A new class of compounds, derived from hydroquinones, has been synthesised and bioassayed for juvenile hormone activity on yellow mealworm (Tenebrio molitor), confused flour beetle (Tribolium confusum), and mediterranean flour moth (Anagasta kuehniella). Structure-biological activity relationships of the most significant products are tabulated and discussed. Two of the new compounds, 1, 4-bis(5-chloropent-4-ynyloxy) benzene (I) and 1-(5-chloropent-4-ynyloxy)-4-phenoxybenzene (II), showed outstanding activity in morphogenetic assay with T. molitor, and good field persistence. Product II is of particular interest for the control of various Homopteran species, mosquitoes, stored product pests and fire ants.     

东亚小花蝽对西花蓟马、二斑叶螨和桃蚜的捕食能力及捕食选择性研究

室内研究了东亚小花蝽对西花蓟马、二斑叶螨和桃蚜的捕食能力及在3种害虫共存条件下的捕食选择性。试验结果表明,东亚小花蝽对西花蓟马、二斑叶螨和桃蚜均具有捕食能力。捕食能力最初随着猎物数量的增加而增加,当猎物数量不断增加时,其捕食量趋于恒定值。在猎物数量充足时,东亚小花蝽对于二斑叶螨、蚜虫和蓟马的日均捕食量分别为17、12.5头和12头。3种猎物共存时,东亚小花蝽对西方花蓟马的捕食选择性均强于对二斑叶螨和桃蚜。选择性依次为西方花蓟马桃蚜≈二斑叶螨。猎物数量相同时取食西花蓟马的数量为12.6头,二斑叶螨和桃蚜的数量分别1.2头和2.4头。     

伪钝绥螨对二斑叶螨的捕食作用

室内条件下研究了伪钝绥螨对二斑叶螨的捕食作用。结果表明：伪钝绥螨雌成螨对二斑叶螨卵、幼螨、若螨和雌成螨的功能反应均符合HollingⅡ型方程,搜寻效率a′与处理时间Th值分别为0.5902、1.0025、0.9697、0.3146和0.0150、0.0240、0.0520、0.1681。伪钝绥螨的雌成螨喜食二斑叶螨的卵、幼螨和若螨,而对二斑叶螨雌成螨的捕食能力较弱。伪钝绥螨捕食率随着自身密度的增加而下降。捕食者密度低时,捕食率下降较快;随着捕食者密度进一步增加,捕食率下降缓慢,干扰反应方程拟合为E=0.3101P~（-0.412）。     

Contradictions in host plant resistance to pests: spider mite (Tetranychus urticae Koch) behaviour undermines the potential resistance of smooth-leaved cotton (Gossypium hirsutum L.)

BACKGROUND: Two‐spotted spider mites (Tetranychus urticae Koch) oviposit near leaf veins or in leaf folds on the undersides of cotton (Gossypium hirsutum L.) leaves where the humid boundary layer offers protection from desiccation. The authors predicted that the boundary layer of glabrous cotton leaves should be shallower than that of hairy leaves, providing some resistance to mites. The dynamics of mite populations, leaf damage, leaf gas exchange and crop yield on two leaf hair isolines (smooth versus hairy) in two genetic backgrounds was assessed. RESULTS: Mite colonies developed faster on the hairy leaf isolines, but leaf damage per mite was higher in smooth leaf isolines, indicating more intense damage. A 50% reduction in photosynthesis on the hairy isolines required 1.8 times more mites than smooth leaves. The yield of cotton was reduced in + mite treatments, but the magnitude of reduction was similar for hairy and smooth isolines. CONCLUSION: Paradoxically, the relative inhospitality of glabrous leaves may have induced mites to concentrate in protected leaf sections, causing more localised and more severe damage, negating the yield benefits from fewer mites. These results highlight interactions between leaf microenvironment, pest behaviour and plant productivity that may have implications for other instances of plant resistance. Copyright © 2010 Society of Chemical Industry     

Chlorfenapyr resistance in the spider mite Tetranychus urticae: stability, cross-resistance and monitoring of resistance

The two-spotted spider mite, Tetranychus urticae Koch, is a key pest of many agricultural crops. Studies of stability of resistance, cross-resistance relationships and monitoring of chlorfenapyr resistance were carried out with T. urticae to provide basic information necessary to define effective acaricide resistance management strategies for this pest. Chlorfenapyr resistance was shown to be stable in the absence of selection pressure under laboratory conditions. The activities of seven different acaricides against chlorfenapyr-resistant and -susceptible strains of T. urticae were evaluated. The results indicated possible positive cross-resistance between chlorfenapyr and the acaricides abamectin, propargite and etoxazole. No cross-resistance was detected for the acaricides milbemectin, fenpyroximate and diafenthiuron. A possible negatively correlated cross-resistance was observed between chlorfenapyr and spiromesifen. The evaluation of 21 T. urticae populations from several crops in the States of São Paulo, Mato Grosso, Goiás, and Bahia, in Brazil, indicated that the susceptibility of mites to chlorfenapyr was variable, with percentages of resistant mites ranging from 0.0 to 86.5%. The highest resistance frequencies were observed in ornamental plants in the State of São Paulo. Some populations from cotton and papaya also presented high frequencies of chlorfenapyr resistance. This is the first report on chlorfenapyr resistance in T. urticae on cotton and papaya in Brazil. Strategies for the management of acaricide resistance are discussed.