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1.
The responses of Tetranychus urticae Koch from Australian cotton to chlorfenapyr has been monitored since the 1997–1998 growing season. Resistance was first detected in the 2001–2002 season and then increased quickly in both level and proportion of resistant strains detected. In response, the resistance management strategy for chlorfenapyr use in cotton was altered and now recommends a further restriction of use from two to one spray per season. There was no evidence of negative cross-resistance to the pyrethroid bifenthrin, but chlorfenapyr was associated with an undefined negative cross-resistance. 相似文献
2.
The management of Tetranychus urticae, a key pest of clementine trees, is mainly based on the use of acaricides. However, more environmentally safe measures, such
as biological control, are being encouraged. Life-history traits of the three most abundant phytoseiid mites associated with
T. urticae on this crop ( Euseius stipulatus, Phytoseiulus persimilis and Neoseiulus californicus) were studied. The experiments were performed under laboratory conditions (25°C, 80 ± 5% RH and 16:8 h (L:D)) on clementine
leaves and T. urticae as prey. Euseius stipulatus could not complete its life cycle, whereas P. persimilis and N. californicus completed it satisfactorily. The estimated intrinsic rate of increase ( r
m) was significantly higher for P. persimilis (0.344 day −1) than for N. californicus (0.244 day −1) and both were higher than the r
m value of T. urticae on clementine leaves. Implications of these results for the biological control of T. urticae in this crop are discussed. 相似文献
3.
AbstractThe two-spotted spider mite, Tetranychus urticae Koch is one of the most common pests of agricultural crops. The use of sublethal doses can reduce the need of pesticides and prevent pests’ resistance, which is an important step in integrated pest management and safely controlling this pest. The sublethal effects (LC 5, LC 15 and LC 35) of spirodiclofen on demographic parameters of T. urticae based on the age-stage, two-sex life table theory were investigated under laboratory conditions [25?±?2?°C, 60?±?5% RH and 16:8 (L:D) h]. The longevity, total life span, oviposition period and total fecundity reduced after exposure to LC 15 and LC 35. Oviposition period ranged from 5.64 to 10.92?days. The gross reproduction rate ( GRR), net reproductive rate ( R0) and the finite rate of increase ( λ) of the mites treated with LC 15 and LC 35 were inferior to the results when treated with LC 5, and control. The values of intrinsic rate of increase ( r) was 0.2209?day ?1 in the control and this was reduced to 0.1714?day ?1 in LC 35. Based on these results, considering the negative impact of spirodiclofen on the population growth of T. urticae, this acaricide can be helpful to achieve an efficient control for T. urticae in frame of integrated pest management. 相似文献
4.
A total of 49 groundcover plant species representing 47 genera in 22 families were identified from a survey of 5 pear orchards. Density of twospotted spider mite ( Tetranychus urticae Koch) inhabiting these plants was estimated visually several times during the field season. Plants were ranked in 1 of 3 categories depending on mite densities found on these plants during the summer. T. urticae was found to be highly abundant (category 3) on 26 species, at lower densities on 10 species (category 2), and was rarely or never found on the remaining 12 species (category 1). Dispersal of mites from groundcover plants into trees was found to be highly variable within and between orchards. Within orchard dispersal appeared to be related to the distribution and abundance of category 3 host plants in the orchard. Variability between orchards may also be affected by groundcover management techniques and levels of acaricide resistance in T. urticae. The use of herbicides to control groundcover plants significantly increased the dispersal of T. urticae into the orchard trees. 相似文献
5.
[目的]丁氟螨酯是一种新型酰基乙腈类非内吸性杀螨剂,对害螨的各个螨态都有很高活性,具有较高的应用价值.本文评价了丁氟螨酯对二斑叶螨生长发育的影响,以期为合理用药和二斑叶螨的综合防治提供理论依据.[方法]采用浸叶法测定丁氟螨酯对二斑叶螨成螨与卵的致死中浓度、雌成螨产卵量、各螨态存活率以及各发育历期的影响.[结果]经丁氟螨... 相似文献
6.
A survey for natural entomopathogenic fungi of two spotted spider mite ( Tetranychus urticae) adults was made in Erzurum, Turkey, during the period 2006. Tetranychus urticae (65.8%) infected with a strain of the fungus Cladosporium cladosporioides were found. Thirteen isolates of C.
cladosporioides were assessed against T. urticae, in a single dose (8 × 10 6 conidia ml −1), laboratory bioassay on bean leaflets. The total mortality percentage caused by C. cladosporioides isolates varied from 50.95 to 74.76% and LT 50 values ranged from 2.34 to 3.90 days. The results revealed that isolates of C. cladosporioides were effective against two spotted spider mite. This is the first record of natural infection of T. urticae by C.
cladosporioides. 相似文献
7.
Tetranychus evansi Baker and Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are important pests of Solanaceae in many countries. Several studies have demonstrated that T. urticae is an acceptable prey to many predatory mites, although the suitability of this prey depends on the host plant. T. evansi, has been shown to be an unfavorable prey to most predatory mites that have been tested against it. The predator Phytoseiulus fragariae Denmark and Schicha (Acari: Phytoseiidae) has been found in association with the two species in Brazil. The objective of
this work was to compare biological parameters of P. fragariae on T. evansi and on T. urticae as prey. The study was conducted under laboratory conditions at 10, 15, 20, 25 and 30°C. At all temperatures, survivorship
was lower on T. evansi than on T. urticae. No predator reached adulthood at 10°C on the former species; even on the latter species, only about 36% of the predators
reached adulthood at 10°C. For both prey, in general, duration of each life stage was shorter, total fecundity was lower and
intrinsic rate of population increase ( r
m
) was higher with increasing temperatures. The slower rate of development of P. fragariae on T. evansi resulted in a slightly higher thermal requirement (103.9 degree-days) on that prey than on T. urticae (97.1 degree-days). The values of net reproduction rate ( R
0), intrinsic rate of increase ( r
m
) and finite rate of increase ( λ) were significantly higher on T. urticae, indicating faster population increase of the predator on this prey species. The highest value of r
m
of the predator was 0.154 and 0.337 female per female per day on T. evansi and on T. urticae, respectively. The results suggested that P. fragariae cannot be considered a good predator of T. evansi. 相似文献
8.
Tetranychus urticae Koch (Acari: Tetranychidae), twospotted spider mite, is a major secondary pest of strawberry and can cause significant yield loss. Tetranychus urticae is typically controlled using miticides, which has led to rapid resistance development. In South Carolina (USA), extension agents and growers have reported field failures of miticides (inadequate pest suppression), but resistance has not been quantitatively determined. In 2018, we determined the level of miticide resistance of six T. urticae populations found on strawberry across South Carolina. We examined efficacy of all miticides registered for use on US strawberry by conducting an initial diagnostic bioassay at 20% of the maximum labeled field rate. Any population?×?active ingredient combination resulting in?<?55% mortality was identified as ‘potentially resistant’ and concentration–response bioassays were then conducted to calculate LC50 values for an individual population. These values were compared with those of a known-susceptible laboratory population to calculate resistance ratios (RR). Our results indicate that examined South Carolina populations of T. urticae from strawberry were highly resistant to bifenthrin (RR?=?100–60,000) and there was reduced susceptibility to fenbutatin-oxide (RR?=?25–123). The 'Sardinia' population had decreased abamectin susceptibility (RR?=?25). No resistance to hexythiazox, etoxazole, acequinocyl, bifenazate, fenpyroximate, spiromesifen, or cyflumetofen was found. Based on available data, it appears that miticide resistance is not a likely cause of field failures and issues related to application error and coverage should be investigated. Overall, this work supports the need to reduce the use of broad-spectrum pesticides and older products, in favor of newer miticide chemistries due to resistance issues. 相似文献
9.
The spatial distribution of motile life stages of the two-spotted spider mite Tetranychus urticae Koch in Kenyan small-scale tomato fields was described by Taylor’s power law and an enumerative sampling plan was designed for research purposes. The exponential increase of T. urticae populations during three growing seasons permits the development and use of a simple exponential model for the design of a threshold-based chemical control system. For this purpose, a critical threshold of 440 motile mites per sample unit at the end of the growing season (12 weeks after transplanting) was translated into a proportion of 0.83 infested units in sample 3, i.e. five weeks after transplanting. A sequential binomial sampling plan with respect to the proportion of 0.83, five weeks after transplanting, was designed. The exponential model was extended to account for the influence of weather and host plant species. Model development and parameter estimation were based on three data sets (Kenyan tomato fields, Italian and Californian strawberry fields). The model satisfactorily predicted a positive influence on growth rates by ( i) changing the host plant from tomato to strawberry, and ( ii) temperature, while a negative effect resulted from ( iii) rainfall; both ( ii) and ( iii) are controlled by temperature–rainfall interactions. In contrast, the estimated parameter values did not satisfactorily describe the expected responses at specific temperature and rainfall values. Nevertheless, the model allowed the rating of host plant species in the field. A fourth data set from Swiss apple orchards was used to test the model, and population build-up on the apple host plant appeared to be higher than on tomatoes but lower than on strawberry. 相似文献
10.
This study aimed to monitor the present and future developments of the resistance of Tetranychus urticae Koch to fenpyroximate and pyridaben, using the relationship of the LC 50 and slope of the concentration-mortality line in a probit model, for the provision of reliable resistance management tactics.
Tetranychus urticae populations were collected from 16 commercial greenhouses, where various crops were cultivated, as well as from 10 apple
orchards throughout Korea. The resistance to fenpyroximate and pyridaben of each population was estimated by calculating the
median lethal concentration (LC 50), resistance ratio (RR) and slope of the concentration-mortality regression. Most of the greenhouse populations exhibited
moderate levels of resistance, whereas the apple orchard populations showed only low levels, indicating that T. urticae populations in greenhouses were more strongly selected than those in apple orchards. Four population groups were established
based on either the habitats (greenhouse and apple orchard) or acaricides (fenpyroximate and pyridaben). To test the hypothesis,
“the slope is greatest at low and high levels of resistance,” the slopes were regressed as a function of the LC 50, and fitted to a polynomial regression. The polynomial regression model explained this relationship well for the four population
groups ( p < 0.05), indicating that the development of resistance toward fenpyroximate or pyridaben was consistent with the gradient.
A laboratory selection study agreed with the results from both acaricide field populations. These results suggest that the
gradient was a good indicator of the susceptibility of T. urticae to genetic variations, which was related to the LC 50. The application of these findings is also discussed in relation to the resistance management of T. urticae. 相似文献
11.
Field experiments (20 m 2 plots) were conducted to compare Azolla and urea as N sources for rice ( Oryza sativa L.) in both the wet and dry seasons. Parallel microplot (1 m 2) experiments were conducted using 15N. A total of approximately 60 kg N ha -1 was applied as urea, Azolla, or urea plus Azolla. Urea or Azolla applied with equal applications of 30 kg N ha -1 at transplanting (T) and at maximum tillering (MT) were equally effective for increasing rice grain yields in both seasons. Urea at 30 kg N ha -1 at T and Azolla 30 kg N ha -1 at MT was also equally effective. Urea applied by the locally recommended best split (40 kg at T and 20 kg at MT) gave a higher yield in the wet season, but an equal yield in the dry season. The average yield increase was 23% in the wet season, and 95% in the dry season. The proportion of the N taken up by the rice plants which was derived from urea (%NdfU) or Azolla (%NdfAz) was essentially identical for the treatments receiving the same N split. Recovery of 15N in the grain plus straw was also very similar. Positive yield responses to residual N were observed in the succeeding rice crop following both the wet and dry seasons, but the increases were not always statistically significant. Recovery of residual 15N ranged from 5.5 to 8.9% for both crops in succeeding seasons. Residual recovery from the urea applications was significantly higher than from Azolla in the crop succeeding the dry season crop. Azolla was equally effective as urea as an N source for rice production on a per kg N basis. 相似文献
12.
Banks grass mite, Oligonychus pratensis (Banks), from three Texas maize fields were assayed for bifenthrin resistance following poor field control in 1995. Laboratory
bioassays showed the field mites to be 3- to 23-fold more tolerant to bifenthrin than the susceptible laboratory culture.
Comparison of LC 50 values to assays with bifenthrin from 1985 to 1993 indicated no statistically significant changes in mite resistance. However,
high LC 90 values in 1995 suggest possible resistance development. The percentages of resistant mites from the three fields in 1995
were calculated to be 4.7%, 17.9%, and 30.9%. The Banks grass mite population exhibiting the highest level of tolerance to
bifenthrin was further assayed to evaluate tolerance levels to other insecticides alone and in combination with synergists
and insecticides. A high level of tolerance existed in the 1995 ‘bifenthrin–selected’ Banks grass mite strain to bifenthrin,
dimeothate, and amitraz. The combination of bifenthrin or dimethoate with a synergist indicated changes in the ability of
the more resistant 1995 mites to detoxify insecticides. The activity of a dimethoate + bifenthrin mixture and a three way
mixture of dimethoate, bifenthrin, and piperonyl butoxide caused 5- and 38-fold increase in toxicity against the more resistant
Banks grass mite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
Using susceptible and resistant reference strains and standard bioassay methods a new miticide product was screened for efficacy and cross-resistance against two-spotted spider mite, Tetranychus urticae Koch. Experimental product NN1 850.0 EW (fenpyroximate and propargite 3:10 ratio) was significantly (P<0.05) more toxic than either compound tested alone (co-toxicity index 1029). Non-overlapping 95% CIs at the LC 50 and LC 99 level suggest that there is no cross-resistance to NN1 850.0 EW from existing organophosphate and pyrethroid resistance. NN1 850.0 EW is worthy of further development for T. urticae control. 相似文献
14.
Seasonal courses of leaf CO 2 gas exchange in a growing season were examined in saplings of Thujopsis dolabrata var. hondai and Quercus mongolica var. grosseserrata in a cool temperate deciduous forest. Between the two tree species there were no large differences in the light compensation
point of leaf photosynthesis, except for the season of new leaf expansion. However, light-saturated rates of net photosynthesis
were obviously high in T. dolabrata var. hondai. Evergreen T. dolabrata var. hondai saplings had large photosynthetic production in two seasons, before the emergence of new foliage and after foliage fall of
the overstory deciduous trees, because of the significantly high solar radiant energy penetrating under the forest canopy
during the seasons. Saplings of deciduous Q. mongolica var. grosseserrata were heavily shaded throughout the growing season by foliage of the overstory trees, which resulted in a low daily surplus
production. The annual surplus production of leaves in the growing season was estimated to be 2300 mmol CO 2 m −2 in T. dolabrata var. hondai and −100 mmol CO 2 m −2, slightly negative, in Q. mongolica var. grosseserrata. These results supported the high survivability of T. dolabrata var. hondai saplings and the high mortality of Q. mongolica var. grosseserrata in the deciduous forest. 相似文献
15.
Two-spotted spider mite, Tetranychus urticae Koch, is one of the most important pests of agricultural products that have a global distribution. Now, the control is dependent on the use of chemical pesticides. The effects of the sublethal concentrations (LC 10 and LC 25) of the essential oil of Cinnamomum zeylanicum were evaluated on some parameters of the life table of the pest, at the constant temperature of 30?°C, relative humidity of 40?±?5% and photoperiod of 16L: 8D. Our results showed that the essential oil of cinnamon is effective on female adult stage. Lethal concentration at which 50% mortality (LC 50) for the essential oils is from C. zeylanicum on female adult mite was 23.39?μl/L air. Sublethal concentrations of the essential oil of C. zeylanicum also impair the natural biology of the mite. Concentrations of sublethal of essential oil decreased age-specific fertility ( mx) of T. urticae compared with the control. Sublethal concentrations (LC 10 and LC 25) have reduced the life expectancy ( ex) in egg stage. Sublethal effects of the essential oil of C. zeylanicum and its impact on T. urticae management are discussed. 相似文献
16.
Sublethal effects of the growth inhibitor, clofentezine, on life-table parameters of Tetranychus urticae Koch females treated at different developmental stages with a concentration causing ≥90% mortality were investigated. Females
which survived treatment as ‘early’ (0–24 h old) eggs produced 12% more offspring than the untreated females during the first
five days of oviposition. This resulted in a significant rise in the intrinsic rate of increase ( r
j
): 0.324, compared to 0.299 in the untreated females. This effect may be interpreted as hormoligosis. Clofentezine treatment
at any other developmental stage of T. urticae significantly decreased both longevity and fertility of female survivors. Females which survived treatment either as ‘late’
(72–96 h old) eggs or larvae had 2.6 times lower net reproductive rate ( R
0) than the untreated females, and the r
j
values were significantly lower: 0.242 and 0.215, respectively (0.285 in the untreated females). Females which survived treatment
either as protonymphs or deutonymphs had 3.9 times and 6 times lower R
0, respectively. Corresponding r
j
values were 0.178 and 0.146, respectively (0.247 in the untreated females). The clofentezine treatment at all stages influenced
the age distribution of survivors. The sublethal effects of clofentezine and their impact on T. urticae management are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
以导入大肠杆菌过氧化氢酶基因KatE的T3代转基因棉花为供试材料,经卡那霉素检测和PCR鉴定,将筛选出的阳性转基因植株与对照棉花进行整个生育期的持续水分胁迫处理直至收获,比较材料间的生理生化指标的差异,鉴定转基因植株的耐旱能力。结果显示:(1)干旱胁迫持续至初蕾期时,转基因棉花与对照植株间各项抗旱生理指标差异均未达到显著水平。(2)水分胁迫持续至盛蕾和盛花期时,转基因棉花叶片相对含水量、光系统Ⅱ最大光化学效率(Fv/Fm)、CAT活性,以及叶片的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著或极显著高于对照植株,叶绿素含量也都明显高于对照植株。干旱胁迫持续至吐絮期时,转基因棉花的株高、果枝数和铃数均显著或极显著高于对照植株,且转基因棉花和对照的籽棉产量分别比正常灌溉处理降低57.5%和60.1%,全生育期的水分胁迫严重影响了棉花籽棉产量,但转基因棉花的籽棉产量仍显著高于对照。研究表明,在新疆石河子当地自然降水(干旱胁迫)条件下,转KatE基因棉花表现出了较好的生理和生长优势,KatE基因有助于提高棉花的抗旱性。 相似文献
18.
Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted
spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C.
The lethal time to 50% mortality (LT 50) and lethal time to 90% mortality (LT 90) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates
at 30 and 35°C; however, significant differences were observed at 20 and 25°C. 相似文献
19.
Competitive displacement is considered the most severe consequence of interspecific competition; if a superior competitor invades the habitat of an inferior species, the inferior species will be displaced. Most displacements previously reported among arthropods were caused by exotic species. The lack of investigation of displacement among native species may be due to their apparently harmonious coexistence, even if it is equivalent to an outcome of interspecific association. A seasonal change in the species composition of spider mites, from Panonychus ulmi to Tetranychus urticae, is observed in apple trees worldwide. Previous laboratory experiments have revealed amensal effects of T. urticae on P. ulmi via their webs. Using manipulation experiments in an orchard, we tested whether this seasonal change in species composition occurred as the result of interspecific competition between these spider mites. Invasion by T. urticae prevented an increase in P. ulmi densities throughout the experimental periods. Degree of overlap relative to the independent distribution on a leaf-surface basis ( ω
S) changed from positive to negative with increasing density of T. urticae. T. urticae invasion drove P. ulmi toward upper leaf surfaces (competitor-free space). The niche adjustment by P. ulmi occurred between leaf surfaces but not among leaves. Our findings show that asymmetrical competition between T. urticae and P. ulmi plays an important role in this unidirectional displacement and that the existence of refuges within a leaf produces the apparently harmonious coexistence of the mites and obscures their negative association. 相似文献
20.
From 1995 to 1999, four experiments were conducted on greenhouse roses to assess the effectiveness of the nC24 petroleum spray oil (PSO), D-C-Tron Plus, against two-spotted mite, Tetranychus urticae Koch (Acarina: Tetranychidae), and to determine how the oil could be most efficiently and effectively used in combination with the predatory mite Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) in an integrated pest management program. The results showed that 0.5% PSO applied fortnightly to roses gave excellent protection from T. urticae infestation when the mite population was not already established. However, PSO applied after roses were infested with T. urticae above the economic threshold only stabilised populations without reducing them below that threshold. Populations of P. persimilis in the upper and lower canopies were unchanged after two sprays of PSO at 7-day intervals, and application of PSO to the upper canopy was as effective in controlling T. urticae in the presence of P. persimilis as spraying the entire plant. Combining PSO with P. persimilis gave better control of T. urticae than using P. persimilis alone. The most cost-effective use of PSO in the presence of P. persimilis is, therefore, to apply spray only to the upper canopy. This will not affect control of powdery mildew with PSO. Comparison of a control program for T. urticae based on the monitored use of synthetic miticides with that based on calendar application of PSO revealed that both gave equally effective control. The benefits of combining PSO and P. persimilis in an integrated pest management program for T. urticae on roses over a program based on synthetic fungicides are discussed. 相似文献
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