scholarly journals Within-Plant Distribution of Two-Spotted Spider Mites, Tetranychus urticae Koch (Acari: Tetranychidae), on Strawberries: Decision of an Optimal Sampling Unit

Insects ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 55
Author(s):  
Yong-Seok Choi ◽  
Min-Jung Kim ◽  
Sunghoon Baek
Keyword(s):  
Tetranychus Urticae ◽  
Leaf Age ◽  
Plant Distribution ◽  
Sampling Unit ◽  
Optimal Sampling ◽  
Trifoliate Leaf ◽  
Significant Difference ◽  
Major Pest ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch

It is known that two-spotted spider mite (Tetranychus urticae), a major pest of strawberry, is difficult to manage. This study was conducted to determine the optimal sampling unit to increase management efficiency of T. urticae in strawberries. The sampling unit was determined by characterizing within-strawberry distribution of T. urticae and by comparing coefficient of variation (CV) and correlation coefficient (r2) among potential sampling units. There was a significant (p < 0.05) difference in densities within a strawberry according to the leaf age. However, there was no significant difference in its density within a trifoliate leaf. More T. urticae were found on young-fully-opened (moderately old) leaves than on young and old ones. Moreover, these leaves had lower CV and r2 values than others. More specifically, optimal sampling units of T. urticae were fifth, fifth or sixth, and sixth oldest leaves for motiles (immatures and adults), all stages (motiles and eggs), and eggs, respectively. The required sampling number should be determined depending on the density. However, for management purposes, one and two leaflets would be acceptable for eggs and motiles, respectively. By using this small number of suitable sampling unit, the sampling and management for T. urticae in strawberries could be more efficient than before.

scholarly journals Soybean (Glycine max L Merr) host-plant defenses and resistance to the two-spotted spider mite (Tetranychus urticae Koch)

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258198
Author(s):  
Ian M. Scott ◽  
Tim McDowell ◽  
Justin B. Renaud ◽  
Sophie W. Krolikowski ◽  
Ling Chen ◽  
...  
Keyword(s):  
Glycine Max ◽  
Tetranychus Urticae ◽  
Spider Mite ◽  
Weather Conditions ◽  
Specialized Metabolites ◽  
Significant Difference ◽  
Depth Analysis ◽  
Glycine Max L ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch

In southern Ontario, Canada, the two-spotted spider mite (Tetranychus urticae) is an emerging pest of soybean (Glycine max) due to the increasing incidence of warmer, drier weather conditions. One key strategy to manage soybean pests is breeding resistant cultivars. Resistance to pathogens and herbivores in soybean has been associated with isoflavonoid phytoalexins, a group of specialized metabolites commonly associated with root, leaf and seed tissues. A survey of 18 Ontario soybean cultivars for spider mite resistance included evaluations of antibiosis and tolerance in relation to isoflavonoid and other metabolites detected in the leaves. Ten-day and 4-week trials beginning with early growth stage plants were used to compare survival, growth, fecundity as well as damage to leaves. Two-spotted spider mite (TSSM) counts were correlated with HPLC measurements of isoflavonoid concentration in the leaves and global metabolite profiling by high resolution LC-MS to identify other metabolites unique to the most resistant (R) and susceptible (S) cultivars. Within 10 days, no significant difference (P>0.05) in resistance to TSSM was determined between cultivars, but after 4 weeks, one cultivar, OAC Avatar, was revealed to have the lowest number of adult TSSMs and their eggs. Other cultivars showing partial resistance included OAC Wallace and OAC Lakeview, while Pagoda was the most tolerant to TSSM feeding. A low, positive correlation between isoflavonoid concentrations and TSSM counts and feeding damage indicated these compounds alone do not explain the range of resistance or tolerance observed. In contrast, other metabolite features were significantly different (P<0.05) in R versus S cultivars. In the presence of TSSM, the R cultivars had significantly greater (P<0.05) concentrations of the free amino acids Trp, Val, Thr, Glu, Asp and His relative to S cultivars. Furthermore, the R cultivar metabolites detected are viable targets for more in-depth analysis of their potential roles in TSSM defense.

scholarly journals The effect of spiromesifen on the reproductive potential of Tetranychus urticae koch (Acari: Tetranychidae)

2009 ◽  
Vol 24 (3) ◽  
pp. 203-209 ◽  
Author(s):  
Dejan Marcic ◽  
Irena Ogurlic ◽  
Slavka Mutavdzic ◽  
Pantelija Peric
Keyword(s):  
Tetranychus Urticae ◽  
Sublethal Effects ◽  
Reproductive Potential ◽  
Instantaneous Rate ◽  
Control Value ◽  
Rate Of Increase ◽  
Significant Difference ◽  
L 51 ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch

Laboratory bioassays were conducted to evaluate the effects of spiromesifen on the fecundity, fertility and population growth of two-spotted spider mite (Tetranychus urticae Koch) after treatment of pre-ovipositing females with five acaricide concentrations: 180 mg/l (maximum recommended concentration for use in glasshouses against spider mites), 18 mg/l, 1.8 mg/l and 0.18 mg/l (the last one was discriminative for eggs and immatures in preliminary studies, i.e. produced 100% mortality of those stages) and 0.018 mg/l. After 24h exposure, the percentages of females surviving treatment without visible symptoms of poisoning were 50% (180 mg/l), 45% (18 mg/l), 51% (1.8 mg/l), 74% (0.18 mg/l), 96% (0.018 mg/l) and 98% (0 mg/l). Over the first four days after treatment, the females that survived 180 mg/l and 18 mg/l laid no eggs. The total number of eggs laid after treatment with these two concentrations was reduced to less than 2% against the control by the end of the trial. The females that survived 1.8 mg/l laid 50% less eggs, compared to the control, while the number of eggs laid by the females treated with 0.18 mg/l and 0.018 mg/l were 19% and 4% lower, respectively. Over the initial four days, egg hatch rates in treatments were 73-87%, and 92-93% in the control. Significant statistical differences between gross fecundity (FCg) and gross fertility (FTg) values in the control and treatments were detected for females surviving 180 mg/l, 18 mg/l and 1.8 mg/l. On the other hand, only the net fertility (FTn) value of females treated with 0.018 mg/l showed no statistically significant difference from the control value. Treatments with 180 mg/l and 18 mg/l significantly reduced the instantaneous rate of increase (ri) 6, 8 and 10 days after treatment, compared to the control. The negative ri values in those treatments indicated a declining population. Sublethal effects of spiromesifen and its impact on T. urticae management are discussed.

Ethyl formate and phosphine fumigations on the two-spotted spider mite, Tetranychus urticae and their biochemical responses

2019 ◽  
Vol 62 (1) ◽  
Author(s):  
Kyeongnam Kim ◽  
Yong Ho Lee ◽  
Gayoung Kim ◽  
Byung-Ho Lee ◽  
Jeong-Oh Yang ◽  
...  
Keyword(s):  
Tetranychus Urticae ◽  
Respiratory Chain ◽  
Spider Mite ◽  
Ethyl Formate ◽  
Treated Group ◽  
Effective Control ◽  
Molecular Approaches ◽  
Significant Difference ◽  
Target Sites ◽  
Two Spotted Spider Mite

Abstract Two spotted spider mite, Tetranychus urticae, is a polyphagous pest to a variety of plants and they are hard to be controlled due to occurrence of resistance to acaricides. In this study, biochemical evaluation after ethyl formate (EF) and phosphine (PH3) fumigation towards T. urticae might help officials to control them in quarantine purposes. PH3 fumigation controlled eggs (LC50; 0.158 mg/L), nymphs (LC50; 0.030 mg/L), and adults (LC50; 0.059 mg/L) of T. urticae, and EF effectively affected nymphs (LC50; 2.826 mg/L) rather than eggs (LC50; 6.797 mg/L) and adults (LC50; 5.836 mg/L). In a longer exposure time of 20 h, PH3 fumigation was 94.2-fold more effective tool for control of T. urticae than EF fumigant. EF and PH3 inhibited cytochrome c oxidase (COX) activity differently in both nymphs and adults of T. urticae. It confirmed COX is one of target sites of these fumigants in T. urticae and COX is involved in the respiratory chain as complex IV. Molecular approaches showed that EF fumigation completely down-regulated the expression of cox11 gene at the concentration of LC10 value, while PH3 up-regulated several genes greater than twofold in T. urticae nymphs treated with the concentration of LC50 value. These increased genes by PH3 fumigation are ndufv1, atpB, para, and ace, responsible for the expression of NADH dehydrogenase [ubiquinone] flavoprotein 1, ATP synthase, and acetylcholinesterase in insects, respectively. Lipidomic analyses exhibited a significant difference between two fumigants-exposed groups and the control, especially an ion with 815.46 m/z was analyzed less than twofold in the fumigants-treated group. It was identified as PI(15:1/18:3) and it may be used as a biomarker to EF and PH3 toxicity. These findings may contribute to set an effective control strategy on T. urticae by methyl bromide alternatives such as EF and PH3 because they have shared target sites on the respiratory chain in the pest.

scholarly journals Effects of local isolates of Beauveria bassiana (Balsamo) Vuillemin on the two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae)

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Cenk Yucel
Keyword(s):  
Tetranychus Urticae ◽  
Beauveria Bassiana ◽  
Spider Mite ◽  
Lethal Effect ◽  
Probit Analysis ◽  
Plant Feeding ◽  
Wide Range ◽  
Two Spotted Spider Mite ◽  
Short Time ◽  
Tetranychus Urticae Koch

Abstract Background The two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae), is a widely distributed plant-feeding pest that causes significant yield losses in a wide range of crops. Newly developed or improved environmentally friendly biocontrol agents serve as an alternative to traditional pest control tools. Experiment of the effects of 2 local fungal isolates of Beauveria bassiana (BGF14 and BCA32) was carried out against T. urticae under laboratory conditions. Results Both tested isolates had lethal effect in a short time after application, and this effect increased as time progressed. BGF14 and BCA32 isolates caused T. urticae mortality rates ranging from 25.88 to 61.92 and 32.36 to 62.03% when applied at the concentrations between 1×105 and 1×108 conidia/ml, respectively. According to the Probit analysis performed on the effect of fungi on T. urticae adults, the LC50 values of BGF14 and BCA32 isolates on the 7th day after inoculation were 2.6×106 and 6.3×104 conidia/ml, respectively, and the LT50 values for both fungi applied at a concentration of 108 conidia/ml were 2.14 and 2.23 days, respectively. Conclusions The 2 isolates of B. bassiana (BGF14 and BCA32) had the potentials to suppress T. urticae population and can be recommended as promising biocontrol agent candidates for control of T. urticae.

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