scholarly journals Relative toxicity of some acaricides to the predatory mite, Amblyseius womersleyi and the twospotted spider mite, Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae).

2001 ◽  
Vol 36 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Sang Soo Kim ◽  
Sang Gi Seo
1981 ◽  
Vol 113 (5) ◽  
pp. 371-378 ◽  
Author(s):  
H. J. Herbert

AbstractThe threshold temperature of development, life table, and innate capacity for increase of the twospotted spider mite, Tetranychus urticae Koch, were established from life stage development studies at constant temperatures. The threshold for development was determined to be 10.0°C. The durations in degree-days above 10°C from the beginning of the egg stage to adult for females were 141.3, 152.3, and 139.8; for males 134.2, 144.7, and 135.2 at 15°, 18°, and 21°C, respectively. Life tables were constructed and innate capacity for increase was .069, .156, and .372; net reproduction rate 20.8, 38.4, and 58.1; and mean generation time 44.0, 23.4, and 10.9 at 15°, 18°, and 21°C, respectively.


1990 ◽  
Vol 25 (1) ◽  
pp. 158-169 ◽  
Author(s):  
D. J. Donahue ◽  
R. M. McPherson

The oviposition response of the twospotted spider mite (TSSM), Tetranychus urticae Koch, to direct treatment and residues of fenvalerate and permethrin on soybean was examined in the laboratory. Contact with pyrethroid residues (120 ppm) reduced eggs per mite-day for 72 h, then oviposition rates returned to normal. Most eggs (99%) on the control leaflets were oviposited directly on the leaf surface, while 83% and 78% of the eggs in the fenvalerate and permethrin treatments were suspended off the leaf surface onto trichomes, cage walls or in the silk webbing. Oviposition rate on untreated soybean foliage following five days on pyrethroid residues was essentially the same for all TSSM; however, the mites previously exposed to fenvalerate or permethrin residue still oviposited 85% and 37% of their eggs off the untreated leaf surface, respectively. A 120 ppm concentration of fenvalerate directly applied to TSSM resulted in 83% and 100% mortality after 24 h and 48 h and no oviposition. A similar direct exposure to permethrin (120 ppm) resulted in 54% mortality after 48 h, and a 58.5% reduction in eggs per mite-day. Direct exposure to a lower dosage rate (12 ppm) caused little mortality but significantly reduced the number of eggs produced in both fenvalerate and permethrin treatments for 48 h. Oviposition returned to normal after 72 h.


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