Mite Populations Research Articles

Parasitic behavior of Pyemotes zhonghuajia (Trombidiformes: Pyemotidae) on fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

Fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a destructive, migratory pest that seriously damages corn, sorghum, and other crops. The “insect killer” Pyemotes zhonghuajia (Trombidiformes: Pyemotidae) is an ectoparasitic mite of agricultural and forestry pests in China. To explore the biological control efficiency of P. zhonghuajia on S. frugiperda, we evaluated the parasitic selectivity of P. zhonghuajia on S. frugiperda of different life stages, and distribution of P. zhonghuajia on different body parts of S. frugiperda larvae and pupae, food intake of S. frugiperda larvae affected by P. zhonghuajia density, and field population dynamics of S. frugiperda in relation to the releasing population density of P. zhonghuajia. We found that P. zhonghuajia preferred 4th- to sixth-instar larvae and pupae of S. frugiperda for parasitism, and the ventral part of abdominal segments of fourth-instar larvae and the ventral part of pupal thorax for feeding. Freezing of S. frugiperda 4th instar larvae and pupae had little effect on the distribution of P. zhonghuajia on the surface of these two host stages. The parasitism of P. zhonghuajia regardless of mite population size (i.e., 5, 10, or 20 mites) could significantly decrease the cumulative food intake of fifth-instar larvae of S. frugiperda. Releasing two and three boxes (50,000 mites/box) of P. zhonghuajia significantly suppressed the field population of S. frugiperda on sorghum plants/25 m2 within 7 days. Our results show that P. zhonghuajia may be a potential biological control agent and can be used for biological control of S. frugiperda in the field.

Varroa Control by Means of a Hyperthermic Device

Hyperthermia is the use of heat to control Varroa destructor. Various apparatuses have been proposed to effectively apply heat and recently the Bee Ethic system was developed in Italy. The Bee Ethic system is a technological hive consisting of a set of heated frames and an electronic control unit. Trials were carried out in the years 2018, 2020 and 2021 to compare colony strength and mite infestation in heat-treated and untreated control bee-hives. In addition, the influence of repeated heat treatments on the development of bee colonies and mite populations was verified by means of a mathematical model. Both in apiary and in silica results show that hyperthermia can be effectively used for V. destructor control within an IPM approach, even in the presence of substantial re-infestation phenomena.

Chilli thrips rose management using an Amblyseius swirskii or Amblydromalus limonicus (Acari: Phytoseiidae) pepper banker plant

AbstractBanker plant systems can enhance biological control of arthropod pests in protected agriculture if they facilitate the persistence of beneficial organisms by providing them with persistent habitats or supplemental food such as pollen or nectar. Ornamental pepper banker plants infested with either the predatory phytoseiid mites Amblyseius swirskii (Athias‐Henriot) or Amblydromalus limonicus (Garman and McGregor) were tested under greenhouse conditions in Florida, USA, for management of the chilli thrips, Scirtothrips dorsalis Hood on Double Knock Out® roses. After two 6‐week studies, performed from October to December 2019 and 2020, both mite species reduced populations of S. dorsalis on roses to nearly undetectable levels (<1 thrips/leaf) compared with predator‐free controls. There was no difference in the mean number of thrips on leaves between the two mite species treatments. Lower S. dorsalis numbers observed on roses when mites were present led to significantly reduced foliar damage assessed as the degree of tissue scarring from S. dorsalis feeding compared with the control. This study may provide rose growers in Florida an alternative option for managing S. dorsalis populations on roses, a typically unsuitable plant for maintaining mite populations.

Population dynamics of mites in slow-release sachets used in biological control: a new study methodology.

Predatory mite species (Acari: Phytoseiidae) are essential tools in the biological control of greenhouses pests. The natural enemies can be released directly into a crop. A better, partly preventive system is to place slow-release sachets on the plants. Inside such sachets is a factitious prey's food substrate-which also acts as refuge-and the predator. The objective of this study was to develop a new methodology to evaluate the population dynamics of this sachet system, based on the factitious prey Carpoglyphus lactis and the predatory mite Amblyseius swirskii. Through two tests carried out under laboratory conditions, the sachets were first compared to the traditional extraction method that uses Berlese-Tullgren funnels and an extraction method using flotation in hexane. The latter method proved more effective at sampling the motile states (larvae, nymphs, and adults), both for the predatory species and for the factitious prey, extracting up to 3.7 × more mites than the Berlese-Tullgren funnel. Second, the population dynamics of both mite species was studied in a laboratory test, both inside and outside the sachets. In this way, a positive correlation was demonstrated between the number of predatory mites and the number of prey mites inside the sachets. Conversely, no correlation was found between the interior population of predatory mites and the number that venture outside. We can conclude that hexane extraction is very useful both in quality control of predatory mites and in studying how the sachets behave when faced with various factors.

830 Topical ivermectin modulates the skin microbiome and improves symptoms of rosacea

Rosacea is a chronic inflammatory skin condition that affects 16 million people in the United States, with worldwide prevalence reported as high as 5%. The pathophysiology of rosacea involves an abnormal innate immune response that may include a response to dysbiosis of the skin microbiome, a condition that contributes to inappropriate inflammation in several disease states. Here, we hypothesized that the clinical improvement in rosacea symptoms with topical ivermectin is due not only to a decrease in the Demodex mite population, but also to a change in the population of commensal skin microbes such as coagulase-negative Staphylococcus (CoNS) that contribute to skin health.

Evaluation of Synthetics and Eco-friendly Products against Tetranychus urticae Koch on Cucumber

Tetranychus urticae Koch, is known as a two-spotted spider mite and the most obtrusive polyphagous non-insect pest that causes havoc on horticultural crops. Cucumber cultivation is threatened by a variety of pest infestations, among which two-spotted spider mites cause the most damage to the crop. The efficiency of six different chemical acaricides against T. urticae in cucumber grown in polyhouse was examined. The results of the acaricide evaluation trial revealed that, the cumulative mean mite population recorded was the least 3.82 nos/ 2 cm2 leaf with 76.81 percent reduction in mite population observed in plot sprayed with spiromesifen 240 SC @ 0.8 ml/lit followed by fenazaquin 10 EC @1.5 ml/lit. with 73.35 percent reduction in mite population (4.39 nos/2 cm2). However, the control plot recorded maximum mite population of 16.48 nos/2 cm2. The results of the eco-friendly management trial revealed that, the cumulative mean mite population was recorded was the least 5.24 nos/ 2 cm2 leaf with 69.97 percent reduction in mite population was observed in plot sprayed with spiromesifen 240 SC @ 0.8 ml/lit followed by fenazaquin 10 EC @1.5 ml/lit. (6.09 nos/2 cm2) with 65.13 per cent reduction, azadirachtin 10000 ppm @ 2 ml/ lit. with 66.82 percent reduction in mite population (6.14 nos/2 cm2).

Mechanisms of Plant Resistance to Rice Leaf Mite, Oligonychus oryzae Hirst (Acari: Tetranychidae)

Due to the changing climatic scenario rice leaf mite, Oligonychus oryzae Hirst becoming one of the major pests of paddy and cause severe yield loss. In this context, field experiment was carried out at Tamil Nadu Agricultural University, Coimbatore to screen popular rice varieties for their resistance against O. oryzae. The results revealed that negative correlation existed between the mite population and the leaf morphological characters viz., the number and length of trichomes, thickness of the leaf lamina and leaf area. ADT 53 a resistant variety recorded 28.48 mg/g of total carbohydrates, while TN 1 susceptible variety recorded 79.59 mg/g. As compared to susceptible variety, the resistant varieties have higher phenol content. The resistant variety Ptb 33 (8.107 changes in OD value min/g of fresh leaf tissue) recorded increased peroxidase activity. Both healthy and infested leaves (0.567 and 0.611 changes in OD value/ min/ g of leaf tissue) from the resistant cultivar Ptb 33 had higher levels of Polyphenol oxidase as compared to other varieties.

First data on water mite (Acari, Hydrachnidia) assemblages of Point Rosa Marsh, Harrison Township, Michigan, USA,and their use as environmental bioindicators of aquatic health

Water mites are aquatic arachnids that have been used in Europe and Central America as bioindicators of ecological health in various freshwater ecosystems (including bogs). Water mites can be found in high densities in the Laurentian Great Lakes and adjacent habitats. Although they are abundant, water mites are generally not used in the assessment of aquatic habitats in the Great Lakes and are usually assigned to the “other” category in macroinvertebrate assessments. This is despite evidence of their utility as aquatic bioindicators. In the present study we consider water mites as bioindicators of the environmental health of Point Rosa marsh, a threatened marsh found on the US side of transboundary Lake St. Clair. The abundance of water mites in Point Rosa Marsh increased from 2017 to 2019 as lake water levels increased. Although increasing water levels in Lake St. Clair can be considered a negative event due to loss of irreplaceable coastal habitat by erosion with potential economic impacts, this present study indicates that water mite populations in Point Rosa Marsh increased during the same period (2017 to 2019). As a result of our study we: update the biodiversity of water mites from Lake St. Clair with new records compared to the last report from the lake over 45 years ago, first report on water mite assemblages at Point Rosa marsh at the Lake St. Clair Metropark on Lake St. Clair and the first demonstration of water mites used as bioindicators in the habitats of the Laurentian Great Lakes.

Seasonal abundance and impact of abiotic factors on major sucking pests of brinjal

The study was carried out to find out the seasonal abundance and impact of abiotic factors on major sucking pests of brinjal. Brinjal variety BR-112 was transplanted on first fortnight of July, 2020 at Research Farm of the Department of Entomology, CCS Haryana Agricultural University, Hisar. The results revealed that the population of whitefly adults and nymphs, jassids, aphids and red spider mite on brinjal was initiated in 28th and 30th, 31st, 48th and 30th Standard Meteorological Week (SMW), respectively. The population build-up of whitefly adults arrived at peak in 42nd SMW when temperature (maximum and minimum) and relative humidity (morning and evening) were 34.2 and 13.7 0C and 76.4 and 22.2 per cent, respectively. The adults of whitefly showed significant positive correlation with maximum temperature while significant negative correlation with morning and evening relative humidity. Whereas jassid population attained its peak in 44th SMW when maximum and minimum temperature was 30.4 and 9.8 0C with 85.4 and 24.0 per cent morning and evening relative humidity, respectively. The peak of aphid population was recorded in 51st SMW when maximum and minimum temperature was 19.7 and 3.0 0C with 91.9 and 42.1 per cent morning and evening relative humidity, respectively. The correlation matrix indicated a significant negative correlation of jassid and aphid minimum temperature while jassid and aphid population recorded non-significant negative correlation with sunshine hours and rainfall. Red spider mite population attained its peak in 40th SMW when maximum and minimum temperature was 36.6 and 18.2 0C with 78.7 and 28.7 per cent morning and evening relative humidity, respectively. The temperature (maximum and minimum) and sunshine hours showed positive non-significant effect, while relative humidity exhibited significant negative correlation with on population build-up of red spider mite.

Biology and Population Dynamics of Two Spotted Spider Mite (Tetranychus urticae Koch) in Cucumber (Cucumis sativus Linnaeus) Under Protected Cultivation

Two spotted spider mite, Tetranychus urticae Koch is the major polyphagous pest on crops and cause considerable yield loss. Cucumber cultivation become possible throughout the year in closed condition with improved agronomic practices. The cultivation of cucumber under controlled condition is threatened by the occurrence of various pests, of which mites occupied greater importance in yield reduction. The influences of weather parameters on population dynamics of T. urticae were studied under protected condition during autumn season of 2021 and continued till last week of April. The observations revealed that the mite population was significantly increased under closed condition and the recorded total developmental period of mites was 6.47 ± 0.003 days, these changes in the biology might resulted from variation in the weather parameters in closed conditions. The population dynamics of two spotted spider mites differed significantly under the protected cultivation compared to the open field condition and a peak population of mites were observed during the second fortnight of march (16th standard meteorological week) and the lowest population was observed during month of November and December as the results of unfavorable environmental condition.

Foliar application of natural products reduces population of two-spotted spider mite, Tetranychus urticae Koch on parthenocarpic cucumber (Cucumis sativus L.) under protected environment

The indigenously prepared natural products namely; cow urine, Darekastra, fermented buttermilk, Panchgavya, Tamarlassi, vermiwash and biopesticide formulations i.e. Azadirachtin 0.15 EC and Eupatorium 5 EC possessing acaricidal activity were evaluated for their bioefficacy against Tetranychus urticae and their effects on cucumber fruit yield under protected environment. After 85 days of transplanting, preventive spray of bioacaricides, vermiwash (15.36 mites/leaf) and Darekastra (16.22 mites/leaf) resulted into lower mite population per leaf whereas curative spray of Darekastra significantly reduced mite population levels (112.53 mites/leaf). The effect of bioacaricide application in the form of spray was also quantified in terms of cucumber fruit yield. The bioacaricides applied as preventive sprays enhanced the cucumber fruit yield. High fruit yield was observed after preventive spray of bioacaricides viz. Tamarlassi (1660.67 g/plant), vermiwash (1656.50 g/plant) and Darekastra (1626.0 g/plant). As curative spray, Darekastra resulted into high fruit yield (1446.33 g/plant). Among the biopesticide checks, Azadirachtin 0.15 EC performed best in managing mite population levels and enhancing the fruit yield under both management measures.

Efficacy of Nicotiana tabacum L. (Solanaceae), Allium sativum L. (Amaryllidaceae) and soft soap for controlling Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae)

The toxicity of bulb extract of garlic, Allium sativum L. (Amaryllidaceae), the leaf extract of tobacco, Nicotiana tabacum L. (Solanaceae), soft soap and the mixtures of soft soap with the garlic and tobacco extracts on Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae) were investigated in the Plant Protection Department of Ordu University between 2014 and 2018 under controlled conditions. The ovicidal and adulticidal effects were tested against 0-24-h-old eggs and newly emerged adult females (1-2 days old) of P. latus, respectively at five concentrations of each extract. The efficacies of the same solutions in controlling the P. latus population were investigated on potted Barbunia bean, Phaseolus vulgaris L., 1753 cv. Barbunia (Fabaceae) plants in a climatic room as well. The results demonstrated that the soft soap and the garlic bulb extract+soft soap mixture are promising for controlling P. latus. The ovicidal effects of soap at 10% and garlic+soap mixture at 20% were 100% and 97.8%, respectively. Additionally, the adulticidal effects of soap at 7.5 and 10% and garlic+soap mixture at 10% were not significantly different and ranged between 90-100%. Also, the soap (10%) and garlic+soap (20%) treatments were able to keep the mite population on bean plants below the economic threshold for 1 week.

ОЦЕНКА УСТОЙЧИВОСТИ СОРТОВ ЗЕМЛЯНИКИ К БОЛЕЗНЯМ И ВРЕДИТЕЛЯМ В ПРЕДУРАЛЬЕ БАШКОРТОСТАНА

When growing strawberries, the susceptibility of plants to diseases and pests is of particular importance. The article presents the results of the study of varieties of garden strawberries for resistance to pests and diseases in the growing seasons of 2017-2020 in the forest-steppe zone of Bashkortostan. The research was conducted in the Kushnarenkov breeding center of the BNIISKH. The material for the study was 26 introduced varieties of wild strawberries of domestic selection. As a control, the zoned variety Orletz was taken. Diseases and pests have a negative effect, reducing the yield of the current and next year. Of particular relevance is the cultivation of varieties with complex resistance to diseases and pests. The degree of harmfulness of pathogens depends on the genotype of the variety and varies with the weather conditions of the growing season. At high humidity and moderate temperature, favorable conditions for the development of diseases arise. The varieties Duet, Rosinka, Slavutich, Solovushka, Naidena, Osokoryanka, and Pervoklassnitsa showed resistance to white and brown leaf spots over the years of study. The group of resistant varieties to gray rot includes the varieties Darenka, Duet, Emelya, Mishutka, Rosinka, Slavutich, Solovushka, Studencheskaya, Troitskaya, Urozhainaya TSGL, Feierverk (yield losses of less than 10%). The varieties Duet, Dewdrop, Studentskaya and Solovushka showed a stable character of resistance to diseases. Low humidity and high temperature lead to an increase in the number of pests. During the study period, the least damage to the raspberry - strawberry weevil was caused by the Bova variety and the control Orlet variety (about 16% of the buds). In arid conditions, strawberry mite populations are small. Signs of stability of the studied varieties can be used in further breeding of strawberries in the conditions of the Pre-Urals of Bashkortostan.

The relation between columbiform birds (Columba livia) age and gender and infection indices of rhinonyssid and ereynetid mites.

Respiratory systems of birds may be parasitized by rhinonyssid and ereynetid mites, which are commonly found in their nasal cavities. Levels of infection caused by mites in relation to maturity and gender of birds have been poorly investigated. Although Columba livia is the host of both Tinaminyssus and Trispeleognathus species worldwide, there are no data on prevalence and mean intensity of infection by mites in immature and adult males and females. Therefore, this study aims to analyze infections in relation to characteristics of hosts in southern Brazil. In the sample of 160 birds under study, 24.38% were parasitized by rhinonyssid mites (Tinaminyssus melloi and Tinaminyssus columbae) while 5.0% were infested with ereynetid ones (Trispeleognathus striatus). Infections by rhinonyssid mites in immature and adult birds, as well as in male and female ones, were similar and there were no significant differences in prevalence and mean intensity of infection. However, when infections were analyzed separately, prevalence of T. melloi was significantly higher in immature (19.77%) than in adult (6.76%) birds (p = 0.021). Ereynetid mites, which parasitized only males, were more prevalent in adult (9.46%) than in immature (1.16%) birds (p = 0.025). Reproductive and behavioral characteristics of C. livia (e.g., year-round breeding and social behavior) may enable transmission and maintenance of mite populations, since direct contact among hosts and the presence of mites in their nests are considered forms of transmission. Even though information on the life history of mites is important to understand parasite-host relations, there is a gap in the biology of species commonly found in C. livia, which constitutes an area to be explored.

Elevated CO2 Increases Overwintering Mortality of Varroa destructor (Mesostigmata: Varroidae) in Honey Bee (Hymenoptera: Apidae) Colonies.

Indoor storage of honey bees (Apis mellifera L.) during winter months has been practiced for decades to protect colonies from the adverse effects of long, harsh winter months. Beekeepers have recently employed indoor storage to reduce labor, feeding costs, theft, and woodenware degradation. Despite the growing number of colonies stored indoors, national survey results still reveal high losses. Varroa mites (Varroa destructor Anderson and Trueman) are the most critical threat to colony winter survival and health of colonies because they contribute to the transmission of viruses and colony mortality. To investigate the effect of high CO2 on varroa mites during the indoor storage of honey bees, 8-frame single deep colonies were stored in two separate environmental chambers at 4°C each. One environmental chamber was set at 8.5% CO2 (high CO2), while the other was set at low CO2 (0.12%). Dead and falling mites were collected and counted from the bottom of individual colonies weekly during the experiment. There was a significant difference in mite mortality of colonies with high CO2 compared to colonies held at low CO2. These results indicated that high CO2 could increase mite mortality during the period of indoor storage, potentially improving honey bee health coming out of the winter months. Our research offers a critical addition to beekeepers' tools for managing varroa mite populations.

Lethal concentrations of Cymbopogon nardus essential oils and their main component citronellal on Varroa destructor and Apis mellifera

Varroosis is a disease caused by the mite Varroa destructor, and it is considered one of the biggest threats to honey bee populations globally. Mite control is centered on the use of synthetic acaricides, such as amitraz and flumethrine. However, high usage of these chemicals is associated with a wide variety of undesirable effects on bee colonies, including the development of resistance and persistence of harmful residues of acaricides in hive products used by humans. Botanical extracts have been identified as a potentially suitable organic alternative to synthetic acaricides. Essential oils, such as clove, eucalyptus, lemongrass, and oregano, have been found to exhibit acaricidal activity against V. destructor. The main goal of this work was to assess the bioactivity of the Cymbopogon nardus essential oil from two different locations (Argentina and India), and the activity of its major component the monoterpene citronellal. According to our results, complete essential oil from India is more effective in controlling parasitosis than the isolated citronellal component. The essential oil of C. nardus from Argentina demonstrated promise for the control of varroosis, as well as exhibiting low toxicity against bees (LC50 = 11.84 μL/mL). In addition, this essential oil may avoid the problems caused by synthetic acaricides, such as the emergence of resistance foci in Varroa and residues in hive products. Future research needs to investigate the delivery of volatile essentials oils to target mite populations.

Development and Evaluation of a New Effective Tool and Method for Assessing Varroadestructor (Acari: Varroidae) Mite Populations in Honey Bee Colonies.

A new device for assessing Varroa destructor (Anderson-Truman) mite infestations in honey bee colonies was designed, tested, and evaluated against the sugar roll method, a widely used method by beekeepers. The Varroa Shaker Device (VSD) is constructed of polyvinyl chloride (PVC) pipe that separates into three parts. Inside the shaker there are two mesh sizes; the larger mesh separates the bees from the mites, and the smaller mesh captures the mites. The VSD can be used by shaking bees with only water as the wash solution. The recovery of mites using the VSD is >90%, which is such as that recorded for using the sugar roll method. Our tests demonstrated that the VSD accurately assessed mite loads when fewer than 250 bees were sampled and shaken with 250 mL of water for one minute. To assure accurate mite counts are achieved with any sampling device, honey bees should be taken from frames with an open and/or capped brood where the mites are more likely located. The VSD can be used in both laboratory and field settings to accurately assess honey bee colonies for levels of mite infestation or for collecting live mites for research purposes.

Population Dynamics of Predatory Mites on Chilies and their Efficacy Against Whitefly (Aleyrodidae) Under Laboratory Conditions

Almost 160 plant species are being infested by whiteflies (Aleyrodidae) throughout South Asian countries including Pakistan. Whiteflies are tiny, sap-sucking insects that may become an abundant pest in vegetable and ornamental plantings, especially during warm weather. Whitefly was initially controlled by using different synthetic chemicals, but now resistance is developed in sucking pests against different groups of chemicals, so the trend has now lifted towards the use of biological control agents. Predatory mites are voracious predators that can feed on all instars of whiteflies including adults. The objective of this trial was to check the population fluctuation of predatory mites on chilies in relation to metrological factors and to know the feeding rates of predatory mites against whiteflies instars under laboratory conditions. According to the results, the maximum population (3.49) of a predatory mite on chilies leaves was observed in the last week of March, while the minimum population (1.34) was observed during 3rd week of February and March which was mainly due to heavy rainfall (34mm in February and 46mm in March). Overall, there was also a small increase in the population with the temperature rise. To evaluate the predatory potential, four treatments (T1, T2, T3, T4), were considered by using different instars of mites in each cell as prey with a predator and T4 as control. Fifteen individuals of each stage of whitefly from eggs to 4th instar were provided in different cells of each predatory mite. The results showed that predatory behavior tends to decrease while feeding against the egg stage to the 4th instar. As in the case of Treatment # 3 (T3), the feeding was gradually reduced against prey from 7.33 to 5.00 while feeding on the 1st to 4th instar. The predatory potential of T1 was less than T3 due to fewer mites in T1 (2/cell). Thus, it is concluded that predatory mites can be used as potential biocontrol agents against all stages of Bemisia species.

Warmer temperatures reduce chemical tolerance in the redlegged earth mite (Halotydeus destructor), an invasive winter-active pest.

BACKGROUNDQuantifying how chemical tolerance of pest arthropods varies with temperature is important for understanding the outcomes of chemical control, for measuring and monitoring resistance, and for predicting how pesticide resistance will evolve under future climate change. We studied the redlegged earth mite, Halotydeus destructor (Tucker), a winter‐active invasive agricultural pest in Australia. Using a replicated block experiment, we tested the effect of different thermal conditions on the expression of chemical tolerance to a pyrethroid and two organophosphates. Our chemical bioassays were conducted on two redlegged earth mite populations: one possessed organophosphate resistance, whilst the other was susceptible to pesticides. Mites were first acclimated at cool (4 °C) and warm (14 °C) conditions and then exposed to pesticides in both cool (11 °C) and warm (18 °C) test conditions.RESULTSWarm test conditions generally reduced chemical tolerance to all pesticides relative to cool test conditions. Median lethal dose (LD50) values of mites tested under cool conditions were 1.12–3.57‐fold greater than of mites tested under warm conditions. Acclimation had a variable and small impact on chemical responses. Thermal factors (ratio between test temperatures) were similar between populations for each active ingredient. Despite reduced chemical tolerances under warm test conditions for individual mite populations, resistance factors (ratio between resistant and susceptible mite populations) were relatively consistent.CONCLUSIONOur data provides context for prior theoretical work demonstrating climatically constrained pesticide resistances in Australian redlegged earth mites. Estimates of temperature dependent toxicity measured in this study may be useful in parameterizing models of redlegged earth mite control under an increasingly warm and more variable climate. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sex and age‐class differences in feather mite loads in white wagtailsMotacilla alba lugenssuggest self‐regulation of feather mites by birds

In order to investigate the relationship between feather mites and their hosts taking into account host ecology I examined relationships among feather mite load, and sex, age, wing length and body‐condition in the white wagtailMotacilla alba lugens. I captured 288 wagtails in January (the first period) 2002 at a communal roost in Osaka, central Japan. All the wagtails were ringed individually, aged as yearlings (first‐winter) or adults (older) and sexed. I measured wing length, tarsus length and body mass, calculated a body condition index (BCI) and determined the feather mite loads (FML) of each individual by visual examination of the flight feathers of one wing, giving a score using the range 0–5. I recaptured 121 wagtails after an average of 45 days (the second period), and redetermined their FML. FML was not correlated with wing length or body‐condition. Yearlings had higher FML than adults in both periods. Males had greater FML than females in the second period. No significant differences in FML between the first and second periods were detected among yearling females, or adult males, but adult females had significantly lower FML and yearling males had significantly higher FML than the other age–sex classes in the second period. The sexual difference was caused by the lower FML of adult females and the higher FML of yearling males. The BCI of yearling males was the lowest among the four combinations of sex and age‐class. I conclude that wagtails may be able to prevent overpopulation of feather mites on their own plumage. The ability to control mite populations may be related to the condition of the host.