Seasonal abundance of spider mite Tetranychus urticae Koch on vegetable and ornamental plants in Rajshahi

The seasonal abundance of spider mite T. urticae on twenty vegetable and twenty four ornamental plants in Rajshahi was conducted during August 2010 to January 2011. The mite was present on joscpks coat, kathua, lady’s finger, cucumber, brinjal, tomato, bottle gourd, bean, loofah, spinach, bitter melon, pointed gourd, radish, and cowpea but no mite was recorded on other six plants. But all the ornamental plants bagan-bilash, bottlebrush, nayantara, morog-jhuti, hasnahena, chandramallika, dalia, krisno-chura, togor, joba, madhobilata, rongon, beli, daisy, sondhamaloti, kamini, musanda, rakto-karobi, shewli, kath-golap, rajanigandha, golap, ganda, zinia contained mites. The pick population was prevailed during August. The increase of mite number is directly related with the increase of temperature. DOI: http://dx.doi.org/10.3329/ujzru.v30i0.10745Univ. j. zool. Rajshahi Univ. Vol. 30, 2011 pp. 37-40

Effect of Selected Insecticide/Acaricides on Twospotted Spider Mite in Virginia Peanut, 1995

Selected insecticide/acaricides were evaluated for efficacy against TSSM in cv. ‘NC 7’ Virginia-type peanut in Isle of Wight County, VA. Peanuts were planted on 4 May using a 36-inch row spacing. All treatments were applied on 28 Jul. The Comite + 5 d treatment was applied again on 5 Aug. Karate, at the 0.025 and 0.04 lb (AI)/acre rates, Capture C, and Danitol were applied again on 9 Aug. All were applied using a CO2 pressurized backpack sprayer calibrated to deliver 14.5 gpa at 50 psi through three D2-13 disc-core hollow cone spray nozzles per row, 1 over the top and 1 on each side. A RCB experimental design was used with 4 replicates; plots were 4 rows by 15 ft. Treatments were evaluated on 28, 31 Jul and on 3, 7, 11, 16, 22 and 29 Aug by comparing the number of live mites in a 1.5 cm diam area on 2 randomly selected leaflets per plot. Mite counts were made in the field using 10x magnification lenses. Data were analyzed using ANOVA and LSD statistical procedures. Cumulative mite-days (CMD) were calculated for each treatment over the entire test period using Σ(Xi+1 – Xi)[(Yi + Yi+1)/2], where Xi and Xi+1 are adjacent sample dates and Yi and Yi+1 are corresponding points of mean mite number per leaflet.

Control of Twospotted Spider Mite in Peanut, 1993

Selected pesticides were evaluated for control of TSSM in cv. ‘NC-10’ Virginia-type peanut in Suffolk, VA. Peanuts were planted using a 36-inch row spacing. Treatments were applied on 28 Jul and again on 10 Aug using a CO2-pressurized back-pack sprayer calibrated to deliver 14.5 gal formulation per acre at 50 psi through three D2-13 disc-core hollow cone spray nozzles per row, 1 over the top and 1 on each side. A RCBD was used with 4 replicates; plots were 4 rows × 20 ft. Treatments were evaluated on 28, 30 Jul and on 3, 5, 10, 13, 20, and 29 Aug by comparing the number of live mites in a 1.5 cm diam area on 4 randomly-selected leaflets per plot. Mite counts were made in the field using 10X magnification lenses. Data were analyzed using ANOVA and LSD statistical procedures. A cumulative index (CI) was calculated for each treatment using ∑(Xi+1 - Xi)[(Yi + Yi+1)/2], where Xi, and Xi+1, are adjacent sample dates and Yi and Yi+1, are corresponding points of total mite number.

EFFECT OF TWO-SPOTTED SPIDER MITE FEEDING ON GAS EXCHANGE AND CHLOROPHYLL CHARACTERISTICS OF RED RASPBERRY LEAVES

At two-week intervals from 17 June to 15 July, three groups of `Meeker' red raspberry plants were infested with two-spotted spider mites (Tetranychus urticae) in a greenhouse. While populations on individual plants were allowed to develop freely, control plants were kept free of mites with a chemical miticide. Gas exchange measurements were made on 27 July prior to visible mite damage, and on 7 October after injury was apparent. The relationships between mite populations and leaf gas exchange and chlorophyll characteristics were described using a logarithmic function.Physiological responses to mite feeding were observed prior to visible leaf injury. On both dates, CO2 assimilation rates decreased (p ≤ 0.001) with increasing mite numbers per leaflet. On 27 June, a significant relationship (R2 = 0.61***) was found between mite number and mesophyll conductance (gm). On 7 October, significant relationships (p ≤ 0.001) were also observed with gm, stomatal conductance (gs), and transpiration (E). Total chlorophyll content of leaves decreased with increasing mite populations, but chlorophyll a/b ratio and dry weight per leaf unit area were unchanged.

Abnormalities in somite segmentation following heat shock to Xenopus embryos

The typical abnormality induced by a 15 min shock at 37 °C is a single discrete length along the so mite file within which segmental boundaries are absent or irregular. The two sides of the same embryo present a similar but not necessarily identical appearance. Usually all the embryos in a treated batch show abnormalities of similar severity. Survival of treated embryos, the details of the visible malformations, and temporal aspects of the phenomenon have been studied. The results indicate a temperature sensitive period that traverses the neurula, from head to tail at about the same rate as the so mites form, but some hours beforehand. The temperature sensitive process is not associated with cell determination and differentiation, and there are reasons for thinking that the specification of the normal so mite number occurs independently. The results are discussed in relation to Cooke & Zeeman's model of a wave front inter-acting with an oscillator.