Gender-Specific Acaricidal Properties and Sexual Transmission of Spirotetramat in Two-Spotted Spider Mite (Tetranychidae: Acariformes)

2019 ◽  
Vol 112 (5) ◽  
pp. 2186-2192
Author(s):  
Sergei Ya Popov ◽  
Andrei Alyokhin

Abstract Two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae: Acariformes), is one of the most important agricultural pests in the world. Their populations have a tendency of rapidly developing resistance to acaricides, making it necessary to have a variety of active ingredients for sustainable chemical control of this pest. We investigated acaricidal properties of a relatively new insecticide spirotetramat using its commercial formulation, Movento Energy. Spirotetramat applied at concentrations equivalent to the field rates of 78 and 90 g ai/ha had a strong negative effect on the survival of the treated T. urticae, with ca. 95% of females and ca. 65% of males dying after the treatment. Spirotetramat appeared to interfere with female reproductive system. Many of the dead treated females had eggs stuck in the oviduct and protruding from their bodies. Surviving treated females did not lay eggs. Furthermore, untreated females that mated with treated males did not produce female offspring and displayed the symptoms of spirotetramat poisoning. Toxic effects continued manifesting themselves after female mites were transferred from treated onto untreated plant culture. Contrary to previous studies, contact toxicity was also detected. None of the treated immature stages survived to adulthood. Based on these results, spirotetramat may be a good option for integrated pest management in crops that are simultaneously affected by sucking insects and spider mites and in pesticide rotation sequences that are a part of integrated resistance management programs.

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Mohamed E. Osman ◽  
Amany A. Abo Elnasr ◽  
Mohamed A. Nawar ◽  
Gohyza A. Hefnawy

Abstract Fungi are a promising source for bioactive secondary metabolites against various agricultural pests. Soil samples were collected from the rhizosphere of various plants at El-Khatatba, Egypt, in May 2016. Sixty-two fungal isolates were locally isolated and screened against Tetranychus urticae Koch (Acari: Tetranychidae). Four fungal strains, showed potent control activities, were morphologically identified. Laboratory evaluation of the crude extracts of the selected strains, Aspergillus melleus, A. terreus, Emericella nidulans, and Chaetomium globosum, exhibited LC50 values of 10.27, 33.05, 14.68, and 22.40 mg/ml against females of T. urticae, respectively. Correspondent LC50 values that exhibited on eggs were 8.81, 23.17, 11.66, and 11.05 mg/ml. Consequently, secondary metabolites of A. melleus were separated by liquid chromatography/mass spectrometry. Compounds separated from the active fraction were identified as mellamide, ochratoxin C, nodulisporic acid, 7-Oxocurvularin, and 6-(4′-hydroxy-2′-methyl phenoxy)-(−)-(3R)-mellein. Obtained secondary metabolites are promising sources for biopesticides to be used in bio-rationale control of T. urticae.


Revista CERES ◽  
2012 ◽  
Vol 59 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Renato Suekane ◽  
Paulo Eduardo Degrande ◽  
Elmo Pontes de Melo ◽  
Thiago Ferreira Bertoncello ◽  
Izidro dos Santos de Lima Junior ◽  
...  

Among phytophagous spider mites, the two-spotted spider mite Tetranychus urticae Koch, 1836 is one of the most important agricultural pests, not only because of the damage it causes, but also because it has a wide host range, infesting many commercial crops such as leafy greens, cotton, beans, and soybeans, among others. This study was carried out in a greenhouse of the Faculdade de Ciências Agrárias (FCA) of the Universidade Federal da Grande Dourados (UFGD), located in the city of Dourados, state of Mato Grosso do Sul. The experiment was arranged in a randomized block design with 5 treatments and 4 replicates. The treatments consisted of 5 levels in percentage of chlorotic symptoms (indicating mite damage): 0%, 25%, 50%, 75%, and 100%. All of the characteristics evaluated, except for number of pods per plant, the number of seeds per plant, the total weight (productivity), and the weight of 1000 seeds, were significantly influenced by the different levels of chlorotic symptoms. The economic damage level for the two-spotted spider mite Tetranychus urticae, according to the equation y = 66.63-0.51 x, based on the price of US$ 11.00 per bag of soybeans and a control cost of US$ 16.00, would be 15.80% chlorotic symptoms. At a price of US$ 29.00 per bag with the same control cost, the economic damage level would be 13% of chlorotic symptoms.


2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Cenk Yucel

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.


Author(s):  
Theodoros I. Stathakis ◽  
Eleftheria V. Kapaxidi ◽  
Georgios Th. Papadoulis ◽  
Nikos E. Papanikolaou

Predation ability is a key component determining the suppression of agricultural pests by natural enemies. The aim of this study is to evaluate the effect of prey density and developmental stage on the predation of Euseius scutalis (Acari: Phytoseiidae) on the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) and the oriental red mite, Eutetranychus orientalis (Acari: Tetranychidae). For this purpose, laboratory functional response experiments were conducted using female adults of E. scutalis. Results indicated that the predator causes an inverse density dependent mortality to larvae, nymphs and adults of the two-spotted spider mite, as well as the oriental red mite. The random predator equation was used to fit the data. E. scutalis handling time increased significantly with T. urticae and E. orientalis developmental stage. The maximum number of T. urticae prey consumed was 48.3 larvae, 28.5 nymphs and 11.0 adults, where the corresponding values for E. orientalis were 48.8, 32.2 and 18.2 larvae, nymphs and adults, respectively. Estimated handling times and attack rates of E. scutalis on larvae, nymphs and adults of T. urticae were 0.4970 h and 0.1058 h-1, 0.8435 h and 0.1395 h-1, and 2.1834 h and 0.0835 h-1, respectively. The corresponding values on larvae, nymphs and adults of E. orientalis were 0.4920 h and 0.1166 h-1, 0.7452 h and 0.1361 h-1, and 1.3186 h and 0.0597 h-1, respectively. The results of this study may be indicative of the predation ability of adults of E. scutalis on these notorious pests, providing a basis for determining release rates appropriate for various pest densities.


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