Contact action of diethylstilbestrol (DES)-impregnated paper strips on pregnant Levant voles: Effect of alteration of DES concentration and of total strip area

Placement of paper strips impregnated with a suspension of diethylstilbestrol (DES) in soybean oil into the cage of a pregnant Levant vole (Microtus guentheri [D. & A.]) causes disruption of pregnancy in almost all cases, provided the DES concentration is at least 0.062 mg/cm² and the total area of the strips is at least 100 cm². When the total strip area is 50 cm² or the DES concentration is 0.031 mg/cm², the activity of the strips is markedly reduced.     

Exposure of females and pups of the levant vole to diethylstilbestrol (DES)-treated nesting material: Effect on the breeding capacity of the female offspring

Adult Levant vole (Microtus guentheri) females, which at the age of 1 or 4 days had been in direct contact for 2 h with filter paper impregnated with a suspension of diethylstilbestrol dipropionate (DES) in soybean oil (0.125 mg DES/cm²), or whose nursing mothers had been in similar contact with DES during that period, were found to be sterile in the overwhelming majority of cases. Females slightly older (5–6 days old) at the time of such contact with DES (direct, or through their nursing mothers) retained their fertility.     

Effect of diethylstilbestrol concentration and duration of contact with nursing Levant voles,on the reproduction of their female offspring

A 5-minute contact of nursing mothers of the Levant vole,Microtus guentheri, with paper impregnated with a DES suspension in soybean oil (125 μg/cm² ) caused sterilization of 60% of the newborn female offspring. A 1-hour contact was sufficient to sterilize more than 90% of them. When the DES concentration was decreased to 1 μg/cm² only 44% of the newborn female offspring were sterile although their nursing mothers had been exposed to contact with the treated paper for a period of 2 hours. The concentration of 0.1 μg/cm² was totally ineffective in causing sterilization. Treatment of nesting material with DES offers a promising means of reproductive suppression in Levant voles.     

Effect of diethylstilbestrol treatment of the Levant vole female during lactation,on the reproduction of her female offspring

Reproduction of 105 females of Levant vole (Microtus guentheri), which ingested diethylstilbestrol (DES) with their mothers’ milk at the age of 0–12 days, and of 62 control females, was studied. In most cases ingestion of DES did not cause sterility, but delayed sexual maturity by 1.5–2 months. This delay was observed in all of the females which ingested DES when they were newborn and 1 day old, in 50% of those that received it at the age of 2 days, and in only 30–40% of those that received it at an older age. Ingestion of DES had no effect on litter size or sex ratio. The total pup production of females which were given DES through their mothers’ milk was about half that of control females.     

A mixed indicator strip for phosphine detection

A rapid, sensitive and reliable mixed indicator paper strip impregnated with dimethyl yellow (0.05%), cresol red (0.1%) and mercuric chloride (1.0%) in methanol has been developed for the detection of phosphine (PH₃) in air at the permissible level (TLV). The paper strip turns red in the presence of phosphine. It is highly sensitive and has better shelf-life than indicator strips impregnated with dimethyl yellow plus mercuric chloride or cresol red plus mercuric chloride.     

From biology to management of Savi's pine vole (Microtus savii)

Savi's pine vole (Microtus savii) is a rodent species of the Cricetidae family, inhabiting southern European agroecosystems. It is considered to be the main cause of rodent‐attributed damage in Italy. To achieve an effective management, detailed knowledge of this species is needed. However, the available information about this species is fragmentary and incomplete. In this paper, the existing knowledge of Savi's pine vole taxonomy, reproduction, population dynamics, habitat and food preferences is reviewed in order to organise available information and identify priority areas of future research. Some of the changes in farming practices that have occurred in recent decades may have increased the impact of Savi's pine vole populations in crop fields. To manage this pest species effectively, an integrated strategy is recommended (involving habitat management, trapping and, when appropriate, the use of rodenticides). The apparent lack of cyclical population outbreaks and the relatively small litter size and long gestation and interpartum period of this species suggest that it could be more manageable than other vole species, while its strict herbivorous diet, stable population size in open habitats and wide distribution seem to indicate it as an ideal model species for risk assessment studies. © 2015 Society of Chemical Industry     

Diethylstilbestrol as a reproduction inhibitor in the Levante vole

Diethylstilbestrol (DES) at 0.019–0.025 mg/g body weight, fed with grain baits to Levante voles (Microtus guentheri [D. & A.]) of different age, sex and physiological condition, suppressed gestation for the first 10 days after mating. These doses, which are consumed voluntarily, also caused sterility in daughters of females which received DES at the end of pregnancy, and sterility or a significant delay (2–3 months) in sexual maturity of females which received it in their mother’s milk during the first days of life. DES had no significant effect on adult nonpregnant females or on males of any age, even if administered 3 days before mating.     

Prognose von Wühlmaussch?den in Forstkulturen

Zusammenfassung  In den Jahren 1980–1990 wurden auf insgesamt 100 Probefl?chen Wühlmausf?nge für die Schadensprognose in Forstkulturen durchgeführt. Die gefangenen Tiere wurden im Labor eingehender untersucht und verschiedene Parameter mit der Dichteentwicklung der Schadnager verglichen. Für einen beschr?nkten Zeitraum von etwa 3 Monaten war die ?u?erlich me?bare L?nge der m?nnlichen Gonaden mit der Populationsentwicklung korreliert. Bei einer mittleren L?nge der Testes über 3,5 mm wurde eine Zunahme der Populationsdichte beobachtet (Gradation). Bei einer geringeren Gonadenl?nge war die Populations-entwicklung rückl?ufig (Retrogradation). Dieser Zusammenhang kann für eine Schadensprognose bedeutsam sein.

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Predicting damages of voles in forest cultivations

Voles like the Field VoleMicrotus agrestis, the Common VoleM. arvalis, the Bank VoleClethrionomys glareolus and the Water VoleArvicola terrestris can cause severe damages in forest cultivations by gnawing the trunks and the roots of the young trees. Damages occur during winter time when the population density of these species is high and food resources are limited. The forecast of the development of vole populations is needed to prepare countermeasures against vole damages. The increase or decrease of a vole population can be predicted, if the fertility of the caught specimens is observed. The gonadal size of the males was a suitable predictor for the trend of the development of a vole population. The change of population density of the Bank Vole in a time interval of 3 month (September–December) was highly correlated (r=0.86) with the gonadal index of males. The percentage of pregnant or lactating femals was also a good indicator, but less suitable for practical use. It is assumed, that the hormones of the hypophysis like FSH, LH and Prolactin rule the growth of the gonads, the fertility and the reproduction in a vole population. Testis size is an indicator for the activity of these fertility hormones and for the reproductive process. It can be used to predict the development of vole populations for a limited time interval.

     

Effect of plant elicitors on the reproduction of the root-knot nematode Meloidogyne chitwoodi on susceptible hosts

Sustainable strategies for plant-parasitic nematode control are required to reduce dependence on chemical nematicides. Foliar application of various compounds can induce a systemic defence response that reduces nematode infestation. The effects of benzothiadiazole (BTH), β-aminobutyric acid (BABA), jasmonates (cis-jasmone and methyl jasmonate) and salicylic acid (SA) in the development and reproduction of the root-knot nematode Meloidogyne chitwoodi in tomato plants were assessed. The effects of BTH and of the jasmonates were further tested on potato plants. Pot assays were conducted using tomato plants cv. Tiny Tim or potato cv. Désirée treated with foliar sprays and inoculated with 300 second stage juveniles. Nematode development and reproduction were assessed 21 and 45 days after inoculation. Treatment with SA had a negative effect on nematode development in tomato plants but did not affect reproduction and methyl jasmonate treatment was the most effective in reducing nematode penetration (58 %). Nematode development was significantly affected in potato plants sprayed with cis-jasmone. Nematode penetration was reduced by 90, 67 and 81 % in plants treated with BTH, cis-jasmone and methyl jasmonate respectively, although the reproduction factor (Rf) was only significantly lower in the BTH treatment (Rf?=?7.6) when compared to the control (Rf?=?18.1). Our results suggest that both the SA and JA pathways play an important role in plant defence mechanisms against root-knot nematode development and reproduction for both plants, and should be considered in the design of integrated pest management approaches.     

Dietary effects upon biological performance and lambda-cyhalothrin susceptibility in the multicolored Asian lady beetle, Harmonia axyridis

Considered a generalist species among the coccinellids, the multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) feeds upon small arthropods and non-prey plant products, a practice which might enhance its ability to colonize various ecosystems but carries the potential to expose it to prey quality variation and insecticide use. Thus, we examined the effect of four different diets on the development, reproduction, and response to the insecticide lambda-cyhalothrin in this species. Three groups of larvae received laboratory-reared diets: (i) eggs of Anagasta kuehniella (Zeller) (Ak); (ii) eggs of Sitotroga cerealella (Olivier) (Sc); and (iii) eggs of A. kuehniella + S. cerealella at the proportion 1:1; and one group received wild-caught cotton aphids, Aphis gossypii Glover (Ag). Notwithstanding the generalist feeding behavior of H. axyridis, development and reproduction results were superior with diets of Ag or Ak compared with the diet combining 1:1 Ak + Sc or the diet of Sc eggs only. Furthermore, the Sc diet did not result in satisfactory development and reproduction. Despite this significant variation in biological responses, insecticide susceptibility studies using adults that had been reared on these diets showed no statistically significant differences in susceptibility to the lambda-cyhalothrin.     

Population Dynamics of the Field Vole (Microtus agrestis [L]): a Model1

The basic hypothesis underlying a population dynamics model for the field vole (Microtus agrestis [L.]) in central Scandinavia is described and discussed. The hypothesis is that most aspects of population dynamics of the field vole may be understood by analyzing the nutritional (energy and matter) balance of individual animals and their differential allocation of available nutrients. Digested nutrients are assumed to be utilized for maintenance cost, M; growth, A S; reproduction, R; and dispersion behaviour (including dispersal), D. The simulation model whose main ideas are described verbally is being developed at present. The model is intended to simulate density, age structure, reproductive activity of different categories of the population and spatial distribution; grazing impact apportioned among the most important potential food species (or group); interaction with sympatric rodents, their predators and parasites. Special emphasis is placed on the spatial heterogeneity of the landscape. The population dynamics model is of the Monte Carlo type and considers the realization of a series of events by calculating average probabilities and “drawing” random numbers. The model simulates individual animals in a large heterogeneous area. Qualitative predictions based on our basic hypothesis are discussed and compared with available field information.     

Effects of a formulation of neem extract on six species of cockroaches (Orthoptera: Blaberidae,Blattidae and Blattellidae)

Margosine-0®, a commercial preparation of neem seed extract, was tested for its effects as a toxicant, growth inhibitor, or repellent against six species of cockroaches —Blatta orientalis L.,Blattella germanica (L.),Byrsotria fumigata Guérin-Méneville,Gromphadorhina portentosa (Schaum),Periplaneta americana (L.), andSupella longipalpa (F.) (Orthoptera: Blaberidae, Blattidae, and Blattel-lidae). Last-instar nymphs of these species fed Lab-Chow® pellets impregnated with neem extract at a rate of 0.5 ml/pellet showed increased mortality and retarded development. All lst-instar nymphs ofB, orientalis, B. germanica andS. longipalpa died after consuming treated Lab-Chow pellets. Topical application of 2 μl of Margosine-0 to the abdomens of last-instarB. orientalis nymphs, as well as injection of 0.5 μl, resulted in reduction of growth and increased mortality. Placing lst-instarB. orientalis nymphs on a surface treated with the neem extract had no notable effect. In a choice test,P. americana adults immediately preferred the pellets treated with 0.5 ml of neem extract, but pint cardboard cartons treated with 1.5 ml extract repelled them.     

Impact of the Common Vole,Microtus arvalis (Pallas) on Winter Wheat and Alfalfa Crops1)

Impact of the common vole, Microtus arvalis (Pallas), upon the winter wheat and alfalfa crops was determined. Net-bottomed coops were used for estimating the effect of vole grazing. Exposure of winter wheat to vole grazing at the stages of earing and flowering was the most harmful. Losses were up to 91% of the potential crop yield, while the proportion of the best grain size fraction (2.8 mm) dropped to a minimum level. Coefficients reflecting the influence of vole grazing on the crop were determined. The coefficient TOTAL is an index of the total impact of consumption. The impact, I_t, at time t equals the consumption, Ct, at this time multiplied by the value of TOTAL. For alfalfa, these coefficients range from 1.28 to 11.73. The results obtained in this study have made it possible to determine the effective rodent pressure on crop yield.     

Plant Damage by Bank Voles (Clethrionomys glareolus [Schreber]) and Related Species in Europe1

A survey of the ecological adaptations of the bank vole, Clethrionomys glareolus (Schreber), indicates that this species is a potential pest, particularly to forest tree seeds and bark. Observations from most parts of Europe show clear cases of damage to seeds, young shoots and buds and bark of young trees above the snow level. Worst losses appear in central and eastern Europe. The bank vole may also attack a few year old seedlings (either bark or complete consumption). Widespread seedling attacks, which are economically very important in some countries, have, however, not been definitely proven for this species. In northern Europe, the bank vole may also cause damage to hay in barns. Bank vole populations show greatest fluctuations in eastern and northern Europe. The cycle length is variable. Damage (except, possibly, seed consumption) appears mainly during or just after the appearance of peak populations. Baits with zinc phosphide seem to be the most efficient control method. A number of other preparations have been tried more or less successfully. In summary, knowledge of the economic importance of the bank vole is very restricted. Specific studies are suggested for improving such an evaluation.     

棕色田鼠种群预测预报研究

１９９２年４月￣１９９５年４月作者在河南灵宝程村黄土塬农作区对棕色田鼠种群数量进行了逐月调查。结果表明,春季３、４月份种群数量高,夏季７、８月份数量低,而秋季１０月份数量又高,然后又降低,呈典型的双峰型。在对棕色田鼠种群年龄结构、繁殖强度等研究的基础上,探讨了种群消长机理和种群调节因子。发现３个月前的成亚比、２个月前的繁殖强度、温度指数、降雨量指数分别和密度呈显著相关,用以上因子建立多元回归方程预     

Common vole (Microtus arvalis) ecology and management: implications for risk assessment of plant protection products

Common voles (Microtus arvalis) are common small mammals in some European landscapes. They can be a major rodent pest in European agriculture and they are also a representative generic focal small herbivorous mammal species used in risk assessment for plant protection products. In this paper, common vole population dynamics, habitat and food preferences, pest potential and use of the common vole as a model small wild mammal species in the risk assessment process are reviewed. Common voles are a component of agroecosystems in many parts of Europe, inhabiting agricultural areas (secondary habitats) when the carrying capacity of primary grassland habitats is exceeded. Colonisation of secondary habitats occurs during multiannual outbreaks, when population sizes can exceed 1000 individuals ha^?1. In such cases, in‐crop common vole population control management has been practised to avoid significant crop damage. The species' status as a crop pest, high fecundity, resilience to disturbance and intermittent colonisation of crop habitats are important characteristics that should be reflected in risk assessment. Based on the information provided in the scientific literature, it seems justified to modify elements of the current risk assessment scheme for plant protection products, including the use of realistic food intake rates, reduced assessment factors or the use of alternativee focal rodent species in particular European regions. Some of these adjustments are already being applied in some EU member states. Therefore, it seems reasonable consistently to apply such pragmatic and realistic approaches in risk assessments for plant protection products across the EU. © 2013 Society of Chemical Industry     

Primer pheromones in the levant vole (microtus guentheri): activation of reproduction in the female by male-related stimuli

Virgin females of the Levant vole (Microtus guentheri), 2–4 months old and raised from weaning in an all-female group, responded to nonvisual male stimuli by an open vagina; the response fluctuated between 5–15% and 30–60%, depending on the stimulation. The priming effect of male-related stimuli on the activation of the female reproductive system was examined using uterine weight as a parameter. In unstimulated virgin females 55–75 days of age raised in an all-female group, the uterine weight showed a temporary spontaneous increase in weight of approximately 45%. Induced increase in uterine weight in such females following stimulation by licking a drop of urine from an intact experienced male was also the strongest at this age. This showed a special sensitivity of the female reproductive system to male stimulation soon after sexual maturation, occurring at the age of about 50 days. Females 55–75 days of age responded with a significant increase in uterine weight already after 1.5 min with an intact experienced male in a cage. The increase in uterine weight was similar whether it was caused by smelling an experienced male’s urine, by chewing a dry filter paper previously impregnated with the urine, or by licking a drop of it. Licking a mixture of fresh male feces in water had no effect. The involvement of the vomeronasal organ in the pheromonal perception was discussed.     

Characterization of the hepatic mixed function oxidase system in endrin-resistant and -susceptible pine voles

Studies were conducted to assess the contribution of the hepatic microsomal mixed function oxidase system to a 7.2-fold difference in susceptibility to the lethal effects of endrin between endrin-resistant and -susceptible pine voles, Microtus pinetorum. Evaluations of microsomal enzyme systems were conducted for basal and endrin-treated pine voles of both strains. The microsomal activity of ICR white mice was investigated to provide a species comparison. Maximal microsomal mixed function oxidase activities were determined in in vitro incubations for the model substrates ethylmorphine, aniline, and benzo(a)pyrene. V_max values were estimated for the rate of disappearance of benzo(a)pyrene in in vitro incubations. No significant strain differences in basal microsomal enzyme activity were found for the model substrates investigated, although activity was invariably higher in the resistant strain. The concentration of cytochrome P-450 was significantly higher in the resistant vole though actually less than 20% different. The occurrence of significant strain differences in the levels of microsomal enzyme activity induced by endrin were rare. Significant endrin treatment effects on the levels of microsomal enzyme activity for the pine vole were observed but the degree and direction of change depended on the substrate used. A marked species difference in microsomal mixed function oxidase activity was noted between pine voles and white mice. This was particularly evident for endrin-treated animals. The microsomal activity of endrin-treated white mice was greatly induced relative to basal levels. The degree of induction depended on the substrate used. The small strain differences in microsomal enzyme activity for the systems investigated were judged to be insufficient to explain the strain difference in susceptibility to endrin.     

Repellence of the red bud borer Resseliella oculiperda from grafted apple trees by impregnation of rubber budding strips with essential oils

The red bud borer Resseliella oculiperda (Rübs.) is a pest insect of apple trees when rootstocks are grafted with scion buds by 'shield budding'. The female midges are attracted to the wounds of the grafted buds where they lay their eggs. The larvae feed on the cambium and destroy the buds completely or partially, leading to bad union of the buds with the rootstocks. Budding strips are used very often by growers to bind scion buds to rootstocks. These strips cannot prevent midges from reaching the damaged tissue. Chemical treatments applied to the grafts and other types of strip do not provide better protection against the pest and may cause other risks for growers. In orchard experiments in 2000 and 2001, the authors evaluated the repellent action provided by three essential oils and five compounds of plant origin against the midges by impregnating budding strips with them. The essential oils of lavender, Lavandula angustifolia (P. Mill.), and alpha-terpineol decreased the infestation of buds by more than 95 and 80% respectively. The other potential repellents tested [the essential oil of Juniperus virginiana (L.), citronellal, the essential oil of Cinnamomum camphora (L.) J. Presl, R-carvone, linalool and R-fenchone] decreased infestation by 67, 66, 51, 45, 37 and 25% respectively. The formulation and commercial development of budding strips impregnated with lavender oil is discussed.     

Effects of different treatment methods of the fungicide jinggangmycin on reproduction and vitellogenin gene (Nlvg) expression in the brown planthopper Nilaparvata lugens Stål (Hemiptera:Delphacidae)

Jinggangmycin is an antibiotic fungicide against the rice sheath blight, Rhizoctonia solani, in China. Previous investigations have shown that jinggangmycin leaf spray stimulated the fecundity of Nilaparvata lugens Stål (Hemiptera:Delphacidae), but the effects of different application methods and concentrations of jinggangmycin on the reproduction of N. lugens have not been investigated. Here, we investigated three treatment methods (foliar and stem sprays and topical treatment) and four concentrations (100, 200, 400 and 800 ppm) of jinggangmycin on the reproduction of adult female N. lugens. The results showed that leaf spray significantly stimulated the fecundity of N. lugens and increased the vitellin content in female ovaries and the gene expression level of vitellogenin (Nlvg), but there was no significant effect on reproduction found for stem spray. In four concentrations of jinggangmycin, leaf sprays at concentrations of 100, 200 and 400 ppm and topical treatments of 100 and 200 ppm significantly increased the number of eggs laid, the vitellin content and the gene expression level of Nlvg compared to the control. Therefore, we suggest that stem spray at high concentration should be applied (if possible) when jinggangmycin is used against rice sheath blight to facilitate harmonious control of rice pests.