scholarly journals Effects of spirodiclofen on the reproductive potential of two-spotted spider mite (Acari: Tetranychidae) ovipositing females

2009 ◽  
Vol 61 (4) ◽  
pp. 777-785 ◽  
Author(s):  
D. Marcic ◽  
Irena Ogurlic ◽  
P. Peric
Keyword(s):  
Spider Mite ◽  
Population Decline ◽  
Survival Rates ◽  
Reproductive Potential ◽  
Adult Emergence ◽  
Egg Laying ◽  
Instantaneous Rate ◽  
Rate Of Increase ◽  
Survival And Reproduction ◽  
Two Spotted Spider Mite

A laboratory bioassay was conducted to evaluate the effects of spirodiclofen on the survival and reproduction of young and mated females of two-spotted spider mite (Tetranychus urticae Koch). The females were sprayed with a series of acaricide concentrations (96, 48, 24, 12, and 6 mg/l) 24-30 h after adult emergence, i.e., at the age most likely to exhibit dispersal behavior and close to their reproductive maximum. The proportions of T. urticae females that survived treatment without symptoms of poisoning were concentration-dependent, ranging between 0.41 and 0.88 (0.96 in the control). With the exception of females that survived 6 mg/l, fecundity of the treated female mites was strongly affected during the exposure, compared to the control. The mean daily fecundity (EL) and mean daily fertility (EH) of surviving females, transferred daily to new leaf disks over the following five days, significantly decreased as spirodiclofen concentrations increased. In treatments with 6 mg/l and 12 mg/l, only the latter concentration significantly reduced both EL and EH, compared to the control. In females that survived 24 mg/l and 48 mg/l, these life history parameters were reduced by over 90%, while treatment with 96 mg/l completely terminated egg-laying. The treated females lived for a significantly shorter time than untreated ones, with the exception of females that survived 6 mg/l. Compared to the control females, gross fecundity (GL) and gross fertility (GH) of the treated females were strongly reduced on the first and second day; from the third day onward, females treated with the lowest concentrations achieved marked recovery, their GL and GH going even above the values in the control. However, net fecundity (NL) and net fertility (NH) of all treated females decreased considerably throughout the trial, indicating that survival rates of these females were lower, compared to the control. Calculated as total sums of gross and net daily schedules within five days, fecundity and fertility significantly decreased as spirodiclofen concentration increased. The two lowest concentrations failed to achieve a significant reduction of GL, while GH, NL, and NH were significantly lower than control values starting with the females treated with 6 mg/L. A high percentage of unhatched eggs, especially during the initial two days after treatment (35-100%), further contributed to the significant reduction in fertility of the females treated with spirodiclofen. All concentrations of spirodiclofen significantly reduced the instantaneous rate of increase. Regression analysis showed a linear population decline with increased acaricide concentrations (y = 1.13 - 0.24x; R2 = 0.91, p < 0.05).

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.

scholarly journals Experts correctly describe demography associated with historical decline of the endangered Indiana bat, but not recent period of stationarity

2017 ◽  
Author(s):  
Wayne Thogmartin ◽  
Carol Sanders-Reed ◽  
Jennifer Szymanski ◽  
Lori Pruitt ◽  
Michael Runge
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Clear Understanding ◽  
Myotis Sodalis ◽  
Indiana Bat ◽  
White Nose Syndrome ◽  
Demographic Behavior ◽  
Pup Survival ◽  
Survival And Reproduction ◽  
Reproductive Rates

Demographic characteristics of bats are often insufficiently described for modeling populations. In data poor situations, experts are often relied upon for characterizing ecological systems. In concert with the development of a matrix model describing Indiana bat (Myotis sodalis) demography, we elicited estimates for parameterizing this model from 12 experts. We conducted this elicitation in two stages, requesting expert values for 12 demographic rates. These rates were adult and juvenile seasonal (winter, summer, fall) survival rates, pup survival in fall, and propensity and success at breeding. Experts were most in agreement about adult fall survival (3% Coefficient of Variation) and least in agreement about propensity of juveniles to breed (37% CV). The experts showed greater concordance for adult ( mean CV, adult = 6.2%) than for juvenile parameters ( mean CV, juvenile = 16.4%), and slightly more agreement for survival (mean CV, survival = 9.8%) compared to reproductive rates ( mean CV, reproduction = 15.1%). However, survival and reproduction were negatively and positively biased, respectively, relative to a stationary dynamic. Despite the species exhibiting near stationary dynamics for two decades prior to the onset of a potential extinction-causing agent, white-nose syndrome, expert estimates indicated a population decline of -11% per year (95% CI = -2%, -20%); quasi-extinction was predicted within a century ( mean = 61 years to QE, range = 32, 97) by 10 of the 12 experts. Were we to use these expert estimates in our modeling efforts, we would have errantly trained our models to a rapidly declining demography asymptomatic of recent demographic behavior. While experts are sometimes the only source of information, a clear understanding of the temporal and spatial context of the information being elicited is necessary to guard against wayward predictions.

scholarly journals Maize plants produce direct resistance elicited by Tetranychus urticae Koch (Acari: Tetranychidae)

2017 ◽  
Vol 78 (1) ◽  
pp. 13-17 ◽  
Author(s):  
P. D. Paulo ◽  
C. G. Lima ◽  
A. B. Dominiquini ◽  
M. A. M. Fadini ◽  
S. M. Mendes ◽  
...  
Keyword(s):  
Tetranychus Urticae ◽  
Spider Mite ◽  
Resistance Mechanisms ◽  
Adult Survival ◽  
Female Adult ◽  
Protective Mechanisms ◽  
Survival And Reproduction ◽  
Maize Plants ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch

Abstract Plants can be attacked by a wide variety of herbivores. Thus, developing protective mechanisms for resistance against these agents is an advantage for survival and reproduction. Over the course of evolution, many resistance mechanisms against herbivory have been developed by the plants. Induced direct and indirect resistance mechanisms can manifest in plants after herbivore attack. The two-spotted spider mite Tetranychus urticae is not a pest of maize crops (Zea mays), despite being reported infesting plants that may have resistances against this herbivore. We tested the hypothesis that maize plants would be able to induce direct resistance against T. urticae after, evaluating the effect of T. urticae infestation in maize plants on the development and reproduction of conspecifics. We tested induced direct resistance performing infestation and measuring biological parameters upon a second infestation. Maize plants, 40 days after sowing, were divided into two groups: 30 not infested by T. urticae (clean plants clean) and, 30 infested by the spider mite. Infestation of maize plants by T. urticae reduced the conspecific female adult survival. However, no change in the survival of immature or reproduction was observed. These results suggest the induction of induced direct resistances in maize by T. urticae. This is first report of direct resistance induction in Z. mays by the two-spotted spider mite T. urticae.

scholarly journals Effects of B-azolemiteacrylic on life-history traits and demographic parameters of two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

2021 ◽  
Author(s):  
Suqin Shang ◽  
Yun Chang ◽  
Wei-Zhen Li ◽  
Wang Chang-Qing ◽  
Nie Peng-Cheng
Keyword(s):  
Tetranychus Urticae ◽  
Spider Mite ◽  
Sublethal Effects ◽  
Oviposition Period ◽  
Population Doubling ◽  
Intrinsic Rate Of Increase ◽  
Population Doubling Time ◽  
Developmental Duration ◽  
Rate Of Increase ◽  
Two Spotted Spider Mite

AbstractThe present study was conducted to evaluate sublethal effects of B-azolemiteacrylic on the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Female adults of T. urticae were exposed to LC10 and LC30 of the acaricide, and the effects on treated females and their offspring were evaluated. The results showed that the fecundity of F0 female adults treated with LC10 and LC30 of B-azolemiteacrylic was reduced by 30.9 and 39.2%, respectively. Longevity and oviposition period of the females were significantly reduced as well. The developmental duration of egg and deutonymph stage of the F1 generation were not significantly different from that of the control. The protonymph stage after LC30 treatment lasted significantly longer, whereas the larva, deutonymph and female stage were significantly shorter than the control. The oviposition period of the F1 generation was significantly shortened, the fecundity of each female decreased significantly, and the ratio of female-to-male was reduced too. Moreover, the average generation period of T. urticae after LC10 and LC30 treatments was shorter than that of the control, and the net production rate (R0), intrinsic rate of increase (rm) and finite rate of increase (λ) were all reduced by 33.3, 7.5 and 1.9% (LC10 treatment) and by 51.3, 14.8 and 3.6% (LC30 treatment), respectively. The population doubling time was prolonged by 7.5 and 14.8% after LC10 and LC30 treatments, respectively, compared with the control. These results indicate that B-azolemiteacrylic may effectively inhibit the development rate of the F0 and F1 populations of T. urticae, which will help design integrated strategies for the comprehensive control of T. urticae and rational use of pesticides in the field.

scholarly journals Experts correctly describe demography associated with historical decline of the endangered Indiana bat, but not recent period of stationarity

2017 ◽  
Author(s):  
Wayne Thogmartin ◽  
Carol Sanders-Reed ◽  
Jennifer Szymanski ◽  
Lori Pruitt ◽  
Michael Runge
Keyword(s):  
Population Decline ◽  
Survival Rates ◽  
Clear Understanding ◽  
Myotis Sodalis ◽  
Indiana Bat ◽  
White Nose Syndrome ◽  
Demographic Behavior ◽  
Pup Survival ◽  
Survival And Reproduction ◽  
Reproductive Rates

Demographic characteristics of bats are often insufficiently described for modeling populations. In data poor situations, experts are often relied upon for characterizing ecological systems. In concert with the development of a matrix model describing Indiana bat (Myotis sodalis) demography, we elicited estimates for parameterizing this model from 12 experts. We conducted this elicitation in two stages, requesting expert values for 12 demographic rates. These rates were adult and juvenile seasonal (winter, summer, fall) survival rates, pup survival in fall, and propensity and success at breeding. Experts were most in agreement about adult fall survival (3% Coefficient of Variation) and least in agreement about propensity of juveniles to breed (37% CV). The experts showed greater concordance for adult ( mean CV, adult = 6.2%) than for juvenile parameters ( mean CV, juvenile = 16.4%), and slightly more agreement for survival (mean CV, survival = 9.8%) compared to reproductive rates ( mean CV, reproduction = 15.1%). However, survival and reproduction were negatively and positively biased, respectively, relative to a stationary dynamic. Despite the species exhibiting near stationary dynamics for two decades prior to the onset of a potential extinction-causing agent, white-nose syndrome, expert estimates indicated a population decline of -11% per year (95% CI = -2%, -20%); quasi-extinction was predicted within a century ( mean = 61 years to QE, range = 32, 97) by 10 of the 12 experts. Were we to use these expert estimates in our modeling efforts, we would have errantly trained our models to a rapidly declining demography asymptomatic of recent demographic behavior. While experts are sometimes the only source of information, a clear understanding of the temporal and spatial context of the information being elicited is necessary to guard against wayward predictions.

Cucumber cultivar responses to two tetranychid mites, two-spotted spider mite and strawberry spider mite in greenhouses

2019 ◽  
Vol 24 (8) ◽  
pp. 1383-1393
Author(s):  
Seyed Saeid Modarres Najafabadi ◽  
Abdoolnabi Bagheri ◽  
Majeed Askari-Seya Hooei
Keyword(s):  
Spider Mite ◽  
Block Design ◽  
Evaluation Criteria ◽  
Injury Rate ◽  
Egg Laying ◽  
Cucumis Sativus L ◽  
Cultivar Responses ◽  
Two Spotted Spider Mite ◽  
Tetranychus Turkestani ◽  
Tetranychus Urticae Koch

Cultivating resistant host plants has been considered as an important strategy for sustainable pest management of mites. The current study was conducted to evaluate the response of 43 cucumber (Cucumis sativus L.) cultivars against two important tetranychid species, two-spotted spider mite (Tetranychus urticae Koch.) and strawberry spider mite (Tetranychus turkestani Ugarov & Nikolski). The experiment was implemented in a Randomized Complete Block design (RCB) with 43 treatments replicated 4 times in a greenhouse during 2015-2016. Two main evaluation criteria, cultivar injury rate (from 1 to 5) and number of eggs/female/day (EFD) on each cultivar, were used to compare responses. The results revealed that the highest number of eggs/female/day (EFD) for both mites was observed on Taha cultivar (9.0±0.40 and 9.5±0.28 for T. urticae and T. turkestani, respectively). The highest injury rate was also observed on this cultivar (4.8±0.26 and 5.0±0.0 for T. urticae and T. turkestani, respectively). In contrast, the lowest EFD number for T. urticae (2.8±0.47) and T. turkestani (2.5±0.28) was seen on Samer star and Davos cultivars, respectively. However, no host preference for egg-laying was observed on Iver and Samer star cultivars for T. turkestani. These two cultivars had the lowest injury level too (1.2±0.25 for Samer star and 1.5±0.28 for Negeen to T. urticae and T. turkestani, respectively). The obtained results demonstrated that Taha was the most susceptible cultivar colonized easily by both two tetranychid species. In contrast, Samer star and Negeen were the most resistant cultivars, strongly recommended for cultivation in greenhouses.

Negative interaction between twospotted spider mites and aphids mediated by feeding damage and honeydew

2012 ◽  
Vol 103 (2) ◽  
pp. 233-240 ◽  
Author(s):  
C.V. Cédola ◽  
M.F. Gugole Ottaviano ◽  
M.E. Brentassi ◽  
M.F. Cingolani ◽  
N.M. Greco
Keyword(s):  
Spider Mite ◽  
Aphid Species ◽  
Negative Interaction ◽  
Experimental Conditions ◽  
Large Numbers ◽  
Rate Of Increase ◽  
Coincidence Index ◽  
And Performance ◽  
Two Spotted Spider Mite ◽  
Negative Interactions

AbstractAmong the herbivorous arthropods that feed on strawberry, the most important are the two-spotted spider mite (TSSM), Tetranychus urticae Koch, and several species of aphids. Mites and aphids belong to different guilds that coexist in the field and feed on the undersides of strawberry leaflets. However, the occurrence of large numbers of individuals of both species on the same leaflet is rarely recorded. We hypothesize that negative interactions between TSSM and aphids explain the intraplant distribution of these herbivores. We first examined the spatial coincidence of both herbivores in the field. Under experimental conditions, we then analyzed: (i) the rate of increase of TSSM and the aphid Chaetosiphon fragaefolii (Cockerell), growing individually and together; (ii) the effect of honeydew on TSSM preference; and (iii) the effect of previous strawberry leaflet damage by TSSM on C. fragaefolii preference. The proportion of TSSM that coincided with at least one aphid decreased as the percentage of leaflets with TSSM increased. The spatial coincidence index between aphids and TSSM increased together with the percentage of TSSM-infested leaflets. TSSM showed both a lower rate of increase when they shared the same leaflet with C. fragaefolii and lower fecundity on strawberry discs with honeydew. The rate of increase of C. fragaefolii did not change on co-occupied leaves, but the aphid species moved to the other side of leaflets shared with TSSM. Negative interactions resulting in a tendency for species to avoid each other, such as demonstrated herein, can affect distribution and performance of herbivorous arthropods.

scholarly journals Resistance of New Strawberry Genotypes to the Two-Spotted Spider Mite (Acari: Tetranychidae)

2017 ◽  
Vol 9 (8) ◽  
pp. 119
Author(s):  
Fernanda De Cássia Neves Esteca ◽  
Camila Do Nascimento Dainese ◽  
Luis Rodolfo Rodrigues ◽  
André Luiz Lourenção ◽  
Francisco Antonio Passos ◽  
...  
Keyword(s):  
Spider Mite ◽  
Intrinsic Rate ◽  
Reproductive Rate ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Artificial Infestation ◽  
Rate Of Increase ◽  
Two Spotted Spider Mite ◽  
Tetranychus Urticae Koch ◽  
Moderately Resistant

The two-spotted spider mite, Tetranychus urticae Koch, is one of the main strawberry pests in Brazil and many other countries. The objective of this study was to compare the resistance of eight strawberry genotypes (‘Albion’, ‘IAC Guarani’, ‘IAC Princesa Isabel’, ‘Oso Grande’, IAC T-0104, IAC 12, IAC 4 and IAC 1.13) to the two-spotted spider mite, by assessing injury level, biological parameters and host preference of the mite. To facilitate the interpretation of the results, leaf trichomes of each genotype were quantified. Thirty days after the artificial infestation of the genotypes with the mite, IAC T-0104, IAC 12 and ‘IAC Princesa Isabel’ showed the lowest injury levels. ‘IAC Princesa Isabel’, IAC 4 and IAC T-0104 were distinguished from other genotypes by the highest mean generation time (T) of the mite, while ‘IAC Guarani’ was distinguished by the lowest T value. Significantly lower values of intrinsic rate of increase (rm), finite rate of increase (λ) and net reproductive rate (Ro) were determined on ‘IAC Princesa Isabel’ and IAC 1.13. The mite showed preference for ‘IAC Guarani’, as inferred by the larger number of females when offered the chance to select the detached host leaflets. Trichome density was highest on IAC 1.13 and lowest on IAC T-0104, IAC 12, ‘Albion’ and ‘Oso Grande’. The results suggested that ‘IAC Princesa Isabel’, IAC T-0104 and IAC 12 are resistant, IAC 4 and IAC 1.13 are moderately resistant, and ‘IAC Guarani’, ‘Oso Grande’ and ‘Albion’ are susceptible to the mite.

THE EFFECT ON THE TWO-SPOTTED SPIDER MITE, TETRANYCHUS URTICAE, OF DICOFOL CONCENTRATION AND DEPOSIT DISTRIBUTION ON THE LEAF SURFACE

1968 ◽  
Vol 100 (7) ◽  
pp. 777-781 ◽  
Author(s):  
R. W. Fisher ◽  
N. G. Morgan
Keyword(s):  
Field Strength ◽  
Tetranychus Urticae ◽  
Adult Female ◽  
Active Ingredient ◽  
Spider Mite ◽  
Leaf Surface ◽  
Egg Laying ◽  
Low Volume ◽  
Two Spotted Spider Mite ◽  
Toxicity Effects

AbstractDicofol was applied to bean leaf discs in various ways. The number of drops per disc, the concentration of dicofol in each drop, and the size of the drops were related to egg laying and mortality of adult female mites placed on the discs. Under the conditions of the experiment, an increase in concentration above normal field strength (0.046% active ingredient) had little effect, even though the deposits were discontinuous and similar to those expected from low-volume spraying. Repellency of dicofol to mites was reaffirmed and toxicity effects were significant when about one-quarter of the leaf surface was covered by deposit.

An experimental study of declining populations

2005 ◽  
Vol 32 (6) ◽  
pp. 481 ◽  
Author(s):  
Jim Hone ◽  
the late Graeme Caughley ◽  
David Grice
Keyword(s):  
Experimental Study ◽  
Population Decline ◽  
Experimental Studies ◽  
Theoretical Models ◽  
Second Phase ◽  
Population Declines ◽  
Negative Effects ◽  
Instantaneous Rate ◽  
Rate Of Increase ◽  
Declining Populations

Wildlife population declines have been attributed to predation, habitat change, and other agents of decline. An experimental study applied predation (at three levels) and habitat (at two levels) treatments over two years and measured the patterns of decline of populations of a medium-sized mammal (European rabbits). A model of population dynamics and effects of the treatments predicted negative effects of both treatments and an interaction of the treatments. All populations declined during the study including the experimental controls. During the first seven months (first phase of the study) the rate of decline, as estimated by the observed monthly instantaneous rate of increase (r), was more negative (P < 0.05) with increasing predation levels but there was no effect (P > 0.05) of habitat manipulation on r. There were no significant effects of treatments on rabbit abundance, or density, during the first phase of the study. During the second phase of the study, of 12 months’ duration, there were no significant (P > 0.05) effects of treatments on rabbit abundance, density, or r. There were no significant (P > 0.05) interactions of treatments on any response variable during either phase of the study. The interaction predicted by the theoretical model was not supported. Estimated abundance at the end of the study was not related (P > 0.05) to initial abundance (correlation = 0.023). The implications of the results are that such experimental studies can be used to evaluate theoretical models, though such studies may require a larger number of treatment replicates, and treatments at more extreme levels, to more clearly detect the effects of agents of population decline and their interactions.

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