Concentrations Of Acaricides Research Articles

Acaricide resistance in Boophilus microplus ticks collected from two ecological Zones of Khyber Pakhtunkhwa, Pakistan.

Boophilus microplus is a major cattle tick specie causing great economic loss to the dairy industry throughout the globe including Pakistan. Trichlorfon and Deltamethrin are used to control bovine ticks, and their sprays are also used in other pest control programs that exert pressure on ticks to gain resistance. This study is aimed to examine the resistance level of Rhipiciphalus microplus against trichlorfon and deltamethrin. The engorged ticks were collected from two ecological regions of Khyber Pakhtunkhwa, KPK Pakistan i.e., Swat & Dir (zone-1), and Charsadda & Nowshera (zone-2). Four concentrations of acaricides in two-fold and ten-fold ppm with three replicates for each were used in both bioassays. Egg hatch assay and adult immersion tests were used to assess the resistance status. The probit analysis of egg hatch assay showed the highest hatching percentage in zone 1 on both dilutions (67-76% on two-fold and 68-88% on ten-fold dilution) while lethal concentration (LC95) was found to be 2.187 ppm and discriminating dose (DD) as 4.374 ppm for trichlorfon. In zone 2, hatching percentage was 73-84 on two-fold and 72-91% on ten-fold dilution while LC95 was recorded as 0.599 ppm and DD as 1.198 ppm. The same parameters were studied for deltamethrin and in zone 1 the hatching percentage was found as 38-56% on two-fold dilution and 37-80% on ten-fold dilution while LC95 was recorded as 0.001 ppm and DD as 0.002 ppm. In zone 2, the hatchability was recorded as 42-58% on two-fold and 43-85% on ten-fold dilution. The values for LC95 was recorded as 0.001 ppm and DD as 0.002 ppm. Further, analysis of adult immersion test against trichlorfon revealed the values of LC50 as 2.85 ppm and LC95 as 4.71 ppm in zone 1 and in zone 2 as 3.14 ppm and 5.28 ppm, respectively. Similarly, LC50 and LC95 against deltamethrin was recorded as 0.79 ppm & 1.71 ppm in zone 1 and 0.45 ppm & 4.325 ppm in zone 2, respectively. Based on the findings of this study, the isolated Rhipicephalus microplus was found to be more resistant to the widely used acaricides i.e., trichlorfon than deltamethrin. In order to maintain the efficacy of acaricides at country level, the study recommends continuous monitoring of resistance.

The effects of the abamectin and spirodiclofen mixture on life history and population parameters of Amblyseius swirskii

In this study, three sublethal concentrations (LC5, LC15, and LC25) of Envidor®speed (Abamectin and Spirodiclofen mixture, 24% SC, Bayer co.) on the biological parameters of the predatory mite Amblyseius swirskii Athias-Heneroit (Acari: Phytoseiidae) fed on Tetranychus urticae Koch (Acari: Tetranychidae) was assessed based on the Two-sex life table theory under laboratory conditions (25 ± 1°C, 70 ± 5% RH and 16:8 (L: D) hours). The data were analyzed based on a two-sex life table procedure. Increasing the sublethal concentration did have a significant effect on some life table parameters. The total lifespan of both males and females treated mites had a decreasing trend, for the females, it increased from 22.10 days in LC25 treatment to 42.67 days in control. The oviposition days of the predatory mite had the most differences between the LC15 and LC25 treatments compared to LC5 and control. Based on our results, the total fecundity is also affected by the acaricidal doses, which changed from 19.10 eggs per individual in LC25 to 37.17 eggs per individual in control. The net reproductive rate (R0), as well as the gross reproductive rate (GRR), were all significantly reduced with increasing the acaricide concentration. The control treatment had the maximum value, and the higher concentration treatment (LC25) had the slowest value of R0 and GRR. On the contrary, the intrinsic rate of increase (r) and finite rate of increase (λ) showed no significant differences with the increasing concentration of acaricide from the control to LC25 treatments. Eventually, with due attention to the large range value of each LCs for predatory mites concerning recommended concentration for T. urticae based on the active ingredient, the recommended concentration of Envidorspeed in IPM programs is unobstructed.

The toxic effects of some acaricides on the tomato russet mite and its predator Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae)

The tomato russet mite, Aculops lycopersici (Massee, 1937) (Acari: Eriophyidae) is a common pest of tomatoes. The predatory mite, Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae), can control A. lycopersici populations. To integrate biological and chemical control of A. lycopersici, side effects of the lethal concentrations of acaricides, as a predator, on A. swirskii should be considered. The lethal concentrations of 14 acaricides for A. lycopersici were determined under laboratory conditions at Bursa Uludağ University during 2017-2018. To understand the toxic impacts of the acaricides on juveniles and females of A. swirskii, the LC99 values for A. lycopersici of each acaricide were applied to A. swirskii. The reproduction reduction effects of the LC99 values were also assessed. Quite low concentrations of abamectin, milbemectin, pyridaben, azadirachtin and sulphur were found to be toxic for A. lycopersici. Based on the side effect scale, the LC99 values of abamectin, acequinocyl, bifenazate, fenproximate, fenbutatin oxide, hexythiazox, milbemectin and sulphur that killed A. lycopersici were found to be slightly toxic to both females and juveniles of A. swirskii. The results of this comparative toxicological study have showed that more field studies should be conducted to evaluate the effectiveness of using low concentrations of acaricides with A. swirskii in combination for controlling A. lycopersici.

New acaricide toxicity on tetranychus urticae koch, selectivity and side effect evaluations on the predatory mite phytoseiulus persimilis athias-henriot (Acari: Phytoseiidae)

The novel mode of action and newer pesticides product molecules is a promising component for agriculture management programs. For this argument some acaricide toxicity evaluations were completed on the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) in laboratory rearing for two generation under acaricide sublethal effect. Toxicity results showed that chlorfenapyr was the most toxic acaricide for Tetranychus urtica Koch and etoxazole was the lesast and for P. persimilis, etoxazole was the most toxic and fenproxymat was the least. Relative toxicity recorded was higher in etoxazole and fenproxymat (7.916 and 5.058 times) respectively. Selectivity data approved that abamectin was the most selective acaricide and etoxazole was the least (8.24 and 0.268) respectively. Effect on first generation of P. persimilis growth fertility and productivity declined, consequently, R0 and rm values where in LC25 attained values ranged from 0.59 to 0.66 for cyflumetofene and hexythiazox, ri data ranged from 0.29 to 0.36 for fenproxymate and cyflumetofene and R0 ranged from 0.53 to 6.0 for cyflumetofene and hexythiazox respectively. But in the second generation similar results attained because declined toxicity where rm in LC25 was from 0.93 and 1.13 for fenproxymat and etoxazole and in LC50 was 0.90 and 1.18 for cyflumetofene and hexythiazox respectively. A high effect on No of eggs /female/day produced, shortened in total time of the generation at LC50 level of treatment more than LC25, and sex ratio resulted more male number emerged than female. The high acaricide concentrations used can kill more T.urtica than P.persimilis.

THEORETICAL-AND-EXPERIMENTAL STUDY OF ACARICIDE CONCENTRATIONS CHANGING IN THE WORKING EMULSION

The animal and the of sheep production quality (especially wool) largely depends on sheep preventive treatment of against parasitic diseases effectiveness. The reliable disease prevention's determining factor is acaricidal substances' stable concentration in working emulsion during sheep treatment observance. At manual of the bath refueling, with 200-300 sheep bathing is carried out, if the first batches at a normal concentration of acaricides in the working emulsion are processed, then subsequent batches in solutions below the recommended values are processed, which is the cause of infectious diseases appearance. So acaricides low concentration in emulsion can lead to ticks' resistant population emergence that develop the using drug's resistance. The methods of theoretical-and-experimental studies analyzing of the of actual data's field experiments on acaricide concentration reducing in the working emulsion during sheep processing were used. As a result, empirical dependences describe regularities of acaricide concentration reducing in the working emulsion's were obtained. At manual bath refueling, regularity exponent has decreasing, that contradicts the quality requirements of animals' antisoroptotic treatment. At bath refueling with a dispenser intensive method, acaricide stable concentration in the working emulsion during the entire period of bathing sheep is observed. The acaricide solution's refueling mass per sheep is 421,7 ± 77,22 ml, depending on the sex and age of sheep groups.

Laboratory evaluation of chlorfenapyr for control of carmine spider mite, Tetranychus cinnabarinus on tomato in Botswana

The efficacy of chlorfenapyr was studied in the laboratory against the carmine spider mite on tomato. The acaricide was applied at five concentrations, including the label rate, separated on a log 10 scale. Each treatment was replicated three times. LC50 and LC90 values were determined by probit analysis during different periods after application and were used to determine the efficacy of the acaricide. LC90 values were 0.52, 0.50, 0.44 and 0.38 ml/L when treatments were evaluated at 24, 48, 72 and 96 hours after treatment. This indicated that chlorfenapyr was highly effective against T. cinnabarinus adults. Probit line slopes were 8.15, 6.96, 5.50 and 2.96 at 24, 48, 72 and 96 hours after application. This indicates a fast change in spider mite mortality with increasing in acaricide concentrations. This study found that chlorfenapyr can be used to effectively control T. cinnabarinus under Botswana conditions, especially in combination with other control methods in integrated pest management programs.

Acaricide resistance of Rhipicephalus decoloratus ticks collected from communal grazing cattle in South Africa.

Objective:This study aimed to determine acaricide resistance in Rhipicephalus decoloratus ticks collected from grazing cattle between November 2018 and May 2019 in Elundini, Senqu, and Walter Sisulu Local Municipalities in the northeastern region of the Eastern Cape Province.Materials and Methods:A sample of 20–30 adult engorged female R. decoloratus ticks were collected from at least 10 randomly selected cattle (highly tick-infested) at each dip tank and placed into the labelled plastic collection bottles containing absorbent paper and with a perforated lid at a constant room temperature of ±28°C and >70% relative humidity until resistance testing commenced. The Shaw larval immersion test method was used to determine R. decoloratus larvae resistance to various acaricide concentration levels [amidines, organophosphate (OP), and synthetic pyrethroids (SPs)].Results:This study found that most ticks were susceptible to exposure to different acaricide field concentrations of amidines (49% at 250 ppm), OPs (33% and 47% at 300 ppm and 500 ppm, respectively), and SPs (44% and 23% at 150 ppm and 300 ppm, respectively). The resistance testing results showed no resistance to amidines at any localities and no resistance to OP in the Senqu region. However, resistance development of the larvae to amines, OPs, and SPs was extensively observed in Senqu (18%, 6%, and 7%), Elundini (15%, 15%, and 17%), and Walter Sisulu (13%, 19%, and 9%) regions, respectively.Conclusions:The larvae’s resistance is a cause for worry. Hence, the continuous monitoring of tick resistance to commonly used acaricides will help mitigate widespread acaricidal resistance and sustain livestock productivity.

Lethal and sublethal effects of fenazaquin and acequinocyl on demographic and some biochemical parameters of Panonychus citri (McGregor) (Acari: Tetranychidae)

ABSTRACT A major pest of citrus orchards in northern regions of Iran is Panonychus citri which is mainly controlled by using chemical acaricides. Knowledge of the lethal and sublethal effects of pesticides on pests is necessary for successful performance of each control programme. In this study, the toxicities of fenazaquin and acequinocyl as well as the effects of the sublethal concentration LC20 and LC30 on demographic and some biochemical traits of P. citri offspring were studied. The results showed that the toxicity of acequinocyl was 2.18 times higher than that of fenazaquin. The developmental time of females was influenced and prolonged by sublethal concentrations of both acaricides. Sublethal concentration effects of both acaricides considerably decreased the total fecundity. A significant reduction was observed in the net reproduction rate (R0 ), and intrinsic rate of natural increase (r) of the mites exposed to LC20 and LC30 concentrations of both acaricides compared to control. Both acaricides showed a negative impact on the content of lipid, carbohydrate, and glycogen. The LC20 concentration of fenazaquin resulted in an increase in general esterase activity, and both acaricides inhibited glutathione S-transferase (GST) activities. Our findings show that the sublethal doses of both acaricides had adverse effects on the biological and physiological characters of P. citri.

Potential causes of Acaricide Resistance in Rhipicephalus and Amblyomma Ticks (Acari: Ixodidae) in Namwala District, Zambia

Acaricide resistance in ticks poses a great threat to livestock production in many parts of the world where ticks are a problem. The objectives of this study were to screen for acaricide resistance in Rhipicephalus and Amblyomma ticks using phenotypic and molecular assays, and to assess current tick control practices used by cattle farmers in the traditional sector of Namwala District. The larval packet test was used to screen for acaricide resistance in ticks covering concentrations up to twice the discriminatory dose for amitraz, diazinon and cypermethrin. Genetic mutations associated with resistance to amitraz (A22C-T8P and T65C-L22S), and organophosphates/ pyrethroids (G1120A) were screened using polymerase chain reaction and sequencing. Information on tick control practices at the household level was collected using a semi-structured questionnaire. Intermediate resistance (21-50%) to amitraz and cypermethrin was detected in both Rhipicephalus and Amblyomma ticks, with both tick genera showing susceptibility to diazinon (<10%). None of the ticks in this study had the reported acaricide resistance-conferring molecular markers that were screened for. The findings suggest that the resistance detected in the studied tick population may be due to other mechanisms yet to be identified. Tick control practices observed amongst the farmers, such as incorrect use of acaricide concentrations and rotations, could be fuelling the development of acaricide resistance. Considering that acaricide treatment is the mainstay of tick control in the country, it is thus critical to comprehensively unravel the factors contributing to treatment failure as this would allow for the application of appropriate remedial actions for effective tick control in Zambia.

<p class="Body"><strong>The effects of bifenazate on life history traits and population growth of <em>Amblyseius swirskii</em> Athias-Henriot (Acari: Phytoseiidae)</strong></p>

Tetranychus urticae Koch (Acari: Tetranychidae) is a notorious crop pest with a worldwide distribution that has developed resistance to a wide range of acaricides. Combined tactics of pest management have special significance not only for a reduction in pesticide residues but also to maintain the natural enemy activity, which is an objective of IPM programs. Here, we investigated the effect of low-lethal concentrations of bifenazate at LC10, LC20, and LC30 on development and reproduction parameters of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). Lethal and sub-lethal concentrations were estimated using leaf dip bioassay method. The crude data were analyzed based on age-stage, two-sex life table analysis. Toxicological assays showed bifenazate treatments gradually decreased the longevity and total life span of both sexes. Our results indicated that reproductive and total fecundity of the next generation were also affected by sublethal concentrations. All concentrations caused a significant decline in oviposition days, compared to the control. The intrinsic rate of increase (rm) varied from 0.1344 to 0.1151 day-1 for the mites treated with distilled water and LC30 treatments, respectively. The finite rate of increase (λ) was affected by the acaricide concentration (lowest at LC30 concentration: 1.1221 day-1). Bifenazate concentration (LC10, LC20 and LC30) treatments gradually reduced the gross reproduction rate (GRR) and net reproductive rate (R0). Based on obtained results from current study, bifenazate is not a favorable acaricide with A. swiriskii and cannot be recommended to use with this predatory mite in integrated management.

Hyalomma anatolicum resistance against ivermectin and fipronil is associated with indiscriminate use of acaricides in southwestern Balochistan, Pakistan.

Ivermectin and fipronil have been used regularly to control the hard tick Hyalomma anatolicum (Acari: Ixodidae) in domestic ruminants for more than a half-decade in Balochistan, Pakistan. Inappropriate and indiscriminate use of these acaricides has resulted in the development of resistances in tick species. In this work, acaricides (ivermectin and fipronil) resistance was evaluated in H. anatolicum through in vitro and in vivo bioassays in a horse farm of Quetta, Balochistan province, Pakistan. A participatory epidemiological survey was conducted to assess potential risk factors associated with the development of acaricide resistance in H. anatolicum. The results of the epidemiological survey revealed that the horse keepers did not follow the manufacturer's instructions for the use of acaricides and applied indiscriminate doses of acaricides. The results of in vitro bioassays (adult immersion test and larval immersion test) showed that fipronil and ivermectin have protective efficacy against H. anatolicum. The results of in vivo bioassay (adult-tick mortality assay) revealed that fipronil had a higher efficacy (78.16%) than ivermectin (49.94%). More than 80% of tick mortality was not achieved in any bioassays, even for the highest acaricide concentration (100ppm), which suggests the development of acaricide resistance against fipronil and ivermectin. This study highlights the urgency to implement a country-wide awareness about resistance monitoring and effective tick control. Graphical abstract.

Acaricides sublethal effects are more harmful to predatory mite Phytoseiulus macropilis Banks (Acari: Phytoseiidae) than to the pest Tetranychus urticae Koch (Acari: Tetranychidae)

To evaluate the lethal and sublethal effect of the abamectin and dimethoate acaricides on the predator P. macropilis and its prey T. urticae. Scope: Lethal and sublethal effect of acaricides on P. macropilis and T. urticae. Methodology: The lethal and sublethal effect of the abamectin and dimethoate acaricides on the predator P. macropilis and its prey T. urticae was determined in laboratory experiments. Main results: T. urticae was 2.6-fold and 4.2-fold more tolerant than P. macropilis to abamectin and dimethoate, respectively. The instantaneous rate of increase of prey and predator decreased linearly with increasing concentrations of both acaricides. However, the instantaneous rate of increase of the predator population decreased more rapidly than that of the pest, resulting in extinction of predator populations, whereas the pest population persisted. Conclusions: Farmers may achieve better control by not spraying acaricides, but managing the populations of this predator in the field using natural enemy conservation techniques.

Role of the interaction of resistance genes to acaricides of different chemical classes in the posterity of diheterozygous females of the two-spotted spider mite

Background. Information on the change in the correlation of genotypes in arthropod populations after treatment of crops with pesticides is essential for effective insectoacaricide resistance management. Materials and methods. Lines of two-spotted mite the homozygous for the gene of resistance to malathion, bifenthrin, bromopropylate and abamectin were obtained by disruptive selection cycles with treatments diagnostic concentrations of these acaricides. Crossing mites were produced heterozygous females with genes of resistance to malation and one of the other three acaricides, as well as families of their filial generation. Females of the three genotypes were compared the value of the degree resistance when testing mites by diagnostic concentrations of acaricides. Results. Combinations of distribution of alleles of resistance to acaricides of different chemical classes in mites of the filial generation of diheterozygous females did not determine the differences from the parent females in the degree of mortality. Conclusion. Epistatic interaction of alleles of resistance to toxicants of different chemical classes allows be used only two insectoacaricides in turn for resistance management.

Role of the interaction of resistance genes to acaricides of different chemical classes in the posterity of diheterozygous females of the two-spotted spider mite

Background. Information on the change in the correlation of genotypes in arthropod populations after treatment of crops with pesticides is essential for effective insectoacaricide resistance management.
 Materials and methods. Lines of two-spotted mite the homozygous for the gene of resistance to malathion, bifenthrin, bromopropylate and abamectin were obtained by disruptive selection cycles with treatments diagnostic concentrations of these acaricides. Crossing mites were produced heterozygous females with genes of resistance to malation and one of the other three acaricides, as well as families of their filial generation. Females of the three genotypes were compared the value of the degree resistance when testing mites by diagnostic concentrations of acaricides.
 Results. Combinations of distribution of alleles of resistance to acaricides of different chemical classes in mites of the filial generation of diheterozygous females did not determine the differences from the parent females in the degree of mortality.
 Conclusion. Epistatic interaction of alleles of resistance to toxicants of different chemical classes allows be used only two insectoacaricides in turn for resistance management.

Heat shock proteins in Varroa destructor exposed to heat stress and in-hive acaricides.

Varroa destructor is one of the major pests that affect honeybees around the world. Chemical treatments are common to control varroosis, but mites possess biochemical adaptive mechanisms to resist these treatments, enabling them to survive. So far, no information is available regarding whether these pesticides can induce the expression of heat shock protein (Hsp) as a common protective mechanism against tissue damage. The aims of this study were to determine differences in heat shock tolerance between mites collected from brood combs and phoretic ones, and to examine patterns of protein expression of Hsp70 that occur in various populations of V. destructor after exposure to acaricides commonly employed in beekeeping, such as flumethrin, tau-fluvalinate and coumaphos. Curiously, mites obtained from brood cells were alive at 40°C, unlike phoretic mites that reached 100% mortality, demonstrating differential thermo-tolerance. Heat treatment induced Hsp70 in mites 4 × more than in control mites and no differences in response were observed in phoretic versus cell-brood-obtained mites. Dose-response assays were carried out at increasing acaricide concentrations. Each population showed a different stress response to acaricides despite belonging to the same geographic region. In one of them, coumaphos acted as a hormetic stressor. Pyrethroids also induced Hsp70, but mite population seemed sensitive to this treatment. We concluded that Hsp70 could represent a robust biomarker for measuring exposure of V. destructor to thermal and chemical stress, depending on the acaricide class and interpopulation variability. This is relevant because it is the first time that stress response is analyzed in this biological model, providing new insight in host-parasite-xenobiotic interaction.

In vitro evaluation of effectiveness of synthetic pyrethroids against brown dog tick

Rhipicephalus sanguineus, the brown dog tick, is one of the most cosmopolitan ixodid ticks of veterinary and public health importance. The domestic dog is the main host of R. sanguineus, but occasionally, can infest a wide range of domestic and wild hosts, including humans. It causes debilitating effects due to blood losses in affected animals and also transmits several pathogens such as Ehrlichia canis, Babesia canis, Haemobartonella canis and Hepatozoon canis. Engorged female R. sanguineus kept for oviposition. Hatched larvae of Rhipicephalus sanguineus were subjected to larval packet test (LPT) to know its efficacy against deltamethrin and cypermethrin. The LC50 and LC95 concentrations were calculated by plotting regression curve of mortality against different concentrations of acaricides. A dose dependent increase in larval mortality was observed for both cypermethrin and deltamethrin. LC50 and LC95 for both deltamethrin and cypermethrin are calculated to be 9.59, 75.87 and 7.08, 219.85, respectively. The results indicated that R. sanguineus ticks were susceptible for cypermethrin, having high percentage mortality at the recommended concentration (200 ppm). However, deltamethrin produced a lower level of mortality at its market recommended dose (25 ppm).

Chemical tick control practices in southwestern and northwestern Uganda

Tick acaricide failure is one of the leading challenges to cattle production in Uganda. To gain an understanding into the possible drivers of acaricide failure, this study characterized the current chemical tick control practices in the southwestern (Mbarara, Mitooma and Rukungiri districts) and northwestern (Adjumani district) regions of Uganda. A total of 85 farms participated in a survey that utilized a semi-structured questionnaire. Moreover, ticks were collected to determine the most common species on the farms. Tick acaricide failure was mainly encountered in the districts where 95% (60/63) of the farms reared exotic cattle (dairy cross-breeds) under a paddocking (fenced) system. In the northwestern region, local cattle were reared in communal grazing areas. All farms used chemical acaricides for tick control, predominantly amidine (amitraz) (48%, 41/85) and co-formulated organophosphates and pyrethroids (38%, 32/85). The spraying method was the most common (91%, 77/85) acaricide application technique, with cattle crush (81%, 69/85) as a common means of physical restraint. Less than optimal tick control practices encountered included use of substandard equipment for spraying, inappropriate dilutions, frequent interaction between animals in neighboring farms despite lack of synchronized chemical tick control and malpractices in acaricide rotation. Only Rhipicephalus appendiculatus and R. (Boophilus) decoloratus ticks were found in the southwestern region, where 51% (32/63) of the farmers used high acaricide concentrations above the manufacturers’ recommendation. Farmers in the northwestern region used 2.2 times less acaricide volume per cattle than those in the southwestern region, and more diverse tick species were encountered. Toxic effects of acaricide to cattle and workers were reported by 13% (11/85) and 32% (27/85) of the respondents, respectively. All 27 cases of human acaricide toxicity reported were from the southwestern region. Overall, our findings may inform strategies for more prudent chemical tick control and safe acaricide handling to benefit animal welfare, food safety and public health.

Physiological mechanism epistatic interaction of resistance genes to acaricides of various chemical classes in the interline hybrids of two-spotted spider mite

Summary: Background. The presence in interline hybrids two-spotted spider mite Tetranychus urticae Koch two genes determining resistance to acaricides of various chemical classes significantly increases their sensitivity to the action of each these toxicants.
 Materials and methods. The resistant and susceptible to malathion, bifenthrin and abamectin inbred lines of spider mite by disruptive selection cycles were obtained. The toxicological tests were performed by diagnostic concentrations of acaricides. The protein marker gene of resistance to malathion was determined by poliacrylamide disc-electrophoresis.
 Results. The epistatic interaction of resistance genes to different acaricides is not manifestation at the stages of transcription and translation of genetic information.
 Conclusion. The epistatic effect of another gene on the resistance gene to the current acaricide is a different consequence of metabolism processes encoded by each gene at the stage of phenotypic regulation.

Detection of deltamethrin resistance in eggs and larva of Rhipicephalus (Boophilus) microplus

Rhipicephalus (Boophilus) microplus is the most common tick species in India infesting cattle and buffaloes and cause significant economic losses to dairy and leather industries by adversely affecting the milk production and quality of hides. Egg hatch assay and larval packet test were used to evaluate the comparative acaricidal efficacy of the market formulations of deltamethrin, cypermethrin and amitraz on eggs and larval stages of R. (B.) microplus. The regression graphs of probit hatchability, % inhibition of hatching (IH) of eggs and probit mortality were plotted against log concentrations of various acaricides. The results revealed that cypermethrin and amitraz were effective and produced complete inhibition of hatching. LC95 values of cypermethrin and amitraz calculated by larval packet test were estimated to be 244.91 ppm and 369.83 ppm, respectively. On the other hand, deltamethrin failed to completely inhibit the hatching. LC95 values by egg hatch assay and larval packet test were estimated to be 42.27 ppm and 39.36 ppm, respectively. The data on field status of acaricide resistance from the area with diversified animal genetic resources will be helpful to adopt suitable strategy to overcome the process of development of resistance in ticks.

Side Effects of Four Acaricides on the Predatory Mites of <i>Neoseiulus californicus</i> McGregor and <i>Phytoseiulus persimilis</i> Athias-Henriot (Acari: Phytoseiidae)

In the present study determined the side effects of four acaricides of acequinocyl, etoxazole, bifenazate and milbemectin on the predator mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor. Acaricide concentrations were prepared as a two times the field application dose (2T), field application dose (T), and half of the field application dose (T/2) and were then applied on eggs, nymphs and adults of the P. persimilis and N. californicus. The side effects of the acaricidesapplied to the predator mites were determined three, five and seven days afterthe application. While all doses of acequinocyl and etoxazole showed a higher toxic effect on N.californicus eggs, it was found that bifenazate and milbemectin caused similar effects on both predator mite eggs. Furthermore, it was found that the toxic effects of acequinocyl, etoxazole, bifenazate and milbemectin on nymphs and adults of the predator miteswere high seventh day after the application. The results of the study showed that four acaracides frequently used against to pest mites, should be used more carefully in the agricultural areas.