Clofentezine toxicity and fate in the bulb mite Rhizoglyphus echinopus (Acari: Acaridae)

Clofentezine was toxic to bulb mite, Rhizoglyphus echinopus (Fumouze and Robin), eggs and larvae; however, it was not toxic to adults alone or in the presence of piperonyl butoxide. When adults were exposed to radioactive clofentezine, the acaricide was absorbed, metabolized and excreted. After 48 h exposure, 49.8% of the recovered radiocarbon was parent compound with 37.1, 9.1 and 3.6% detected in the container rinse, mite rinse and internal fraction, respectively. Homogenates of adults extensively metabolized clofentezine. The most active fraction was the 12 000 g supernatant plus glutathione followed in decreasing order by the supernatant, supernatant plus NADPH and the whole homogenate, each of which metabolized at least 16% of the acaricide. In the presence of piperonyl butoxide, in vitro metabolism of clofentezine by each of these active fractions was increased approximately 10%. Although it is possible that rapid metabolism could have contributed to the lack of toxicity of clofentezine to bulb mite adults, it is more likely that another major mechanism was involved. Perhaps adult bulb mites lack the sensitive target found in immature mites.     

Toxicological studies of the carbamates methomyl and bendiocarb in the bulb mite Rhizoglyphus echinopus (Acari: Acaridae)

Methomyl was 15 and 31.3 times more toxic than bendiocarb to bulb mites at the LC50 and LC90 values respectively. However, methomyl (pI50 3.0) was at least 126 times less active than bendiocarb (pI50 5.1) as an inhibitor of bulb mite cholinesterase in vitro. The disparity between the high toxicity of methomyl and its extremely low activity as an inhibitor of mite cholinesterase in vitro indicated that another mechanism was likely involved in its toxic action. Pharmacokinetic studies of methomyl and bendiocarb showed that penetration and metabolism were rapid and that there were no substantial differences in the internal levels of the respective parent carbamates during the 24 h test period. However, volatile radioactive material(s), some of which was carbon dioxide, was produced in appreciably greater amounts from methomyl than from bendiocarb. We speculate that the production of volatiles, such as carbon dioxide, acetonitrile and/or methylamine, may contribute to the toxicity of methomyl to bulb mites. © Rapid Science Ltd. 1998     

食物对刺足根螨生长发育、繁殖及休眠体产生的影响

在(25±1)℃、(95±5)%RH、全黑暗条件下,研究了4种食物对刺足根螨生长发育、繁殖及休眠体产生的影响。结果表明:取食马铃薯、马铃薯淀粉及鱼粉后,刺足根螨能完成世代发育,但其取食滤纸不能完成世代发育;在适宜的温湿度条件下,供试的4种食物对刺足根螨休眠体的产生无影响。     

Heritability of male morph in the bulb mite, Rhizoglyphus robini (Astigmata, Acaridae)

In several species of Acaridae (Astigmata), heteromorphic males, possessing a sharply terminated third pair of legs which they use to mortally stab other males, coexist with scrambler males with unmodified legs. Previous research showed that in the bulb mite, Rhizoglyphus robini (Claparède), the male morph is heritable. In this study I used a different population and carried out selection in both downward and upward direction in order to change the proportion of morphs. Starting from the proportion of about 0.2 homeomorphs in the population, I obtained a significant response to 8–10 generations of selection in two repetitions. The response was asymmetrical (stronger in upward direction). Realised heritabilities were in the range of 0.3 (downward) and 0.8 (upward).     

Procrustean analysis of fluctuating asymmetry in the bulb mite Rhizoglyphus robini Claparede (Astigmata: Acaridae)

We studied fluctuating asymmetry (FA) in two generations of the bulb mite Rhizoglyphus robini . We used Procrustes analyses, which allow the comparison of dimensionless shapes of body sides. We found little (<4%) directional asymmetry in either sex. Of the two morphs occurring in this species, fighters, which possess a thickened third pair of legs, exhibited higher FA than did scramblers, the morph with unmodified legs; this may reflect the costliness of the fighter developmental pathway. There was a negative relationship between FA and female fecundity, but the regression slope of mid-offspring on mid-parent FA was not significantly greater than zero. We propose that heritability estimates can be biased downwards if highly asymmetric individuals produce fewer viable offspring. However, we found no significant association between parental FA and the proportion of viable embryos in their broods. Furthermore, we hypothesized that parental FA might indicate the presence of largely recessive mutations deleterious to developmental homeostasis that would cause increased embryo mortality under inbreeding. However, we found no significant association between FA of parents that were mated to their full sibs and the proportion of viable embryos in their inbred progeny.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 499–505.     

Bulb mite,Rhizoglyphus robini (Astigmata: Acaridae) as an experimental animal

Rhizoglyphus robini Claparède (Acari: Astigmata: Acaridae) is proposed as a model laboratory animal for biological, ecological, physiological and toxicological studies. The mite is easy and inexpensive to rear, quite fecund, convenient to manipulate, and may rapidly be raised to gram quantities. Examples are presented of its use in soil pest ecology and control studies, and in physiological, biochemical and toxicological investigations. Efforts to explore the induction of detoxification systems by various chemicals, and a demonstration of its control by solarization, are also described.     

Penetration of pesticides into the bulb miteRhizoglyphus echinopus (Acari: Acaridae)

Bulb mites,Rhizoglyphus echinopus (Fumoze and Robin), were exposed for 10 min in vials precoated with 23 radiocarbon-labeled pesticides, and the kinetics of penetration were assessed following post-exposure periods of 320 min or 24h, depending upon the compound. With all pesticides, penetration was biphasic and consisted of a rapid initial component (alpha phase) followed by a much slower secondary component. The alpha phase of penetration was analyzed with a linear model, and the entire penetration curve was analyzed with a non-linear model. Correlation analyses of ten mass balance and penetration parameters and partition coefficients yielded 14 combinations that were significant atP<0.05. It was found that compounds with the fastest penetration rates had the highest dosing coefficients and the lowest octanol-water partition coefficients. Thus, fastest penetration was associated with relatively polar compounds such as oxythioquinox, promecarb, methomyl, aldicarb, and chlordimeform, whereas slowest penetration was observed with lipophilic compounds such as DDT, diflubenzuron, di-2-ethylhexyl phthalate, and the pyrethroids. However, the polar formetanate hydrochloride penetrated very slowly and was an exception to this generalization. These results provide a basis for suggesting that pesticide penetration proceeded at a faster rate in bulb mites than in two-spotted spider mites,Tetranychus urticae Koch, in other studies.     

Properties of choline acetyltransferase from the bulb miteRhizoglyphus echinopus (Acari: Acaridae)

In the presence of exogenous acetyl coenzyme A¹⁴-C and choline, the 20 000 g supernatant fraction of whole bulb-mite homogenates synthesized a radioactive product that chromatographed with authentic acetylcholine (ACh). ApparentK _m values were 0.12 and 1.14 mM for acetyl coenzyme A and choline, respectively, and the average rate of ACh synthesis was 2.06 mol h^–1 g^–1 equivalent of mite tissue (wet weight). Choline acetyltransferase (ChAT) activity was inhibited by 5,5-dithiobis(2-nitrobenzoic acid), suggesting the presence of functionally important sulfhydryl groups. However, ChAT activity was not inhibited by 27 acaricides from several different chemical classes, except for the thiazolidine flubenzimine which gave a pI₅₀ of 3.5 mol l^–1.Contribution from the Missouri Agricultural Experiment Station, Columbia, Missouri, Journal Series No. 11 157.     

Biology, ecology, and management of the bulb mites of the genus Rhizoglyphus (Acari: Acaridae)

Bulb mites of the genus Rhizoglyphus (Claparède) (Acari: Acaridae) have been identified as pests of many crops and ornamentals in storage, in the greenhouse, and in the field. The most importanthosts are species in the family Liliaceae (e.g. Allium spp.), but bulb mites will often attack otherimportant crops such as potatoes (Solanum sp.) and carrots (Daucus carota). Despite their economicimportance and broad distribution, the systematics of the genus remains in a state of confusion and is inneed of a comprehensive revision. In addition, the field biology and ecology of these mites is not wellunderstood, and methods for sampling, monitoring, and loss assessment are limited. Management of bulbmites is complicated by their short generation time, high reproductive potential, broad food niche,interactions with other pests and pathogens, and unique adaptations for dispersal. Historically, control ofthese acarine pests has relied on the use of synthetic miticides and insecticides, but this option is nowlimited due to documented resistance and withdrawal of registration of some products. Alternativecontrol strategies, including cultural and biological control, have shown limited success, but need to befurther developed and implemented.     

Sexual selection and conflict in the bulb mite, <Emphasis Type="Italic">Rhizoglyphus robini</Emphasis> (Astigmata: Acaridae)

Whether benefits of mate choice accrued by females outweigh costs associated with sexual selection remains largely unresolved. The ‘good genes’ perspective, posing that mate choice benefits females genetically has been challenged by the arguments that sexual selection is driven mostly by direct costs and inter-sexual conflict. Here, I present an overview of experimental tests of predictions of good genes and sexual conflict mechanisms in the bulb mite Rhizoglyphus robini.     

Cholinesterase inhibition in the bulb miteRhizoglyphus echinopus (Acari: Acaridae) in relation to the acaricidal action of organophosphates and carbamates

The 5000-g supernatant fraction of whole-bulb-mite homogenates was shown to possess a cholinesterase (ChE) that hydrolyzed acylcholine esters in the order acetyl>propionyl>butyryl. Acetyl--methylcholine, but not benzoylcholine, also was hydrolyzed as were acetylthiocholine and acetyl--methylthiocholine. No inhibition by excess substrate was observed at cholinester concentrations as high as 30mM. Cholinesterase activity was markedly insensitive to eserine and to certain other carbamates and organophosphates. Only organophosphates of the dimethylphosphate type generally were active ChE inhibitors. It was concluded that the inability of carbamates such as eserine, and organophosphates such as those with alkyl groups larger than dimethyl, to inhibit the bulb-mite ChE was probably a consequence of the nature of the esteratic site. The data suggested that ChE inhibition was likely involved in the toxicity to bulb mites of some of the toxic carbamates and organophosphates, but that it might not be the only mechanism involved, at least with several of the compounds.Contribution from the Missouri Agricultural Experiment Station, Columbia, MO, Journal Series No. 10 924.     

Toxicity of Acaricides to the Bulb Mite Rhizoglyphus Echinopus (Acari: Acaridae)

Using a continuous exposure technique, the toxicity of 35 compounds to the bulb mite, Rhizoglyphus echinopus (Fumouze and Robin) was examined after 48 h. Sixteen acaricides yielded an LC₅₀ of <1.0 mg cm². The highest toxicity was exhibited by cyclodiene GABA antagonists (dieldrin, endrin and aldrin), some organophosphate (chlorpyrifos, diazinon and azinphosethyl) and carbamate (carbofuran) anticholinesterases and a thiazolidine flubenzimine. Oxythioquinox, fenazaflor, fenazaquin and amitraz were less toxic than the cyclodienes, organophosphates and carbamates. The sodium channel agonists (DDT and pyrethroids) and several specific acaricides with other modes of action were inactive (LC₅₀ >11.0 mg cm^-2).     

Amplification of single bulb mites by nested PCR: Species-specific primers to detect Rhizoglyphus robini and R. setosus (Acari: Acaridae)

A major problem of using molecular amplicons for DNA amplification in mite systematics is that sufficient template cannot always be acquired from an individual mite. To solve this problem, we developed a nested PCR for DNA amplification of single Rhizoglyphus robini and R. setosus bulb mites. A dilution up to 10⁵ of the DNA from a single egg, larva, nymph or adult contained enough templates for amplification of the target ribosomal region. However, the use of specific primers in the second PCR is necessary to reduce the generation of non-target DNAs from symbiotic organisms. Identification of bulb mites collected from seven sampling locations in Taiwan or of bulb mites that were used in simulated experiments in the presence of host plant tissues was unambiguous with specific PCR primers.     

Energy budget of the grain mite,Acarus siro (Acari: Acaridae)

Immature individuals ofAcarus siro L. ingest a total of 0.1408 J of food energy, 58.5% of which is consumed by the deutonymph, 27.1% by the protonymph and only 14.1% by the larva. The total ingestion is much greater (2.8169 J±0.0981se). Much energy, 0.7031 J±0.0231se, is used for egg production, which is concentrated in the first 20 days of adult life. Assimilation efficiency during this period varies from 63 to 71%. Most energy ingested between the 20th and 40th days of adult life is used in biomass production, and biomass increases significantly up to th 30th day. Afterwards, old individuals expend a large amount of assimilated energy on respiration due to the increased cost of maintenance.Present address: Biology Dept., LB 8042, Georgia Southern University, Statesboro, GA 30460, U.S.A.     

根螨属螨类进境风险分析

通过对根螨进境风险进行定性分析,初步认为花叶芋根螨(Rhizoglyphus caladii)、小根螨(R.minutus)、长毛根螨(R.setosus)和单列根螨(R.singularis)为检疫性有害生物;刺足根螨(R.echinopus)和罗宾根螨(R.robini)为限定的非检疫性有害生物。     

A new genus and species of mite (Acari: Acaridae) from Mexico

Comerinia chuetolamina gen. & sp. nov. was collected from a cargo of dried Daphnia imported to Britain from Mexico. Females can be distinguished from all others described in the family Acaridae in that setae 14, 15 and d5 are flattened dorsoventrally over most of the basal half. This region appears blade-like, bearing numerous strong pectinations along the ventral side. Males may be recognized by a series of characters, some of which reflect a close relationship with Forcellinia Ouds., 1924 and others with Tyrophagus Ouds., 1924. The position of the new genus in a commonly used key to adults of the family Acaridae is indicated.     

Transformation of hypopodes ofRhizoglyphus robini (Acari: Astigmata: Acaridae) on cultures of three soil fungi

Cultures of three soil plant pathogens were tested for their influence on transformation of hypopodes ofRhizoglyphus robini Claparede to the tritonymphal stage. Potato-dextrose agar (PDA) substrate was used to growBotrytis gladiolorum Timmermans,Curvularia trifolii f. sp.gladioli Parmelee and Latterell, andFusarium oxysporum f. sp.perniciosum (Hepting) Toole. Hypopodes were placed directly on the agar cultures of these fungi and on plain PDA. No significant differences were found in total number of hypopodes transformed or in rate of transformation.Research supported in part by United States—Israel BARD Project No. I-140-79.     

Epoxide hydrolase in the bulb mite Rhizoglyphus robini: properties and induction

Using styrene oxide as substrate, most of the epoxide hydrolase (EH) activity monitored in the bulb mite Rhizoglyphus robini was associated with the microsomal compartment. The microsomal and cytosolic EHs did not display any significant preference in hydrating trans stilbene oxide (TSO) and cis stilbene oxide (CSO). The microsomal EH, which has a Km value of 5×10^-5M and pH optimum of 7.8, was sensitive to ethanol and its activity was inhibited to a moderate extent by 4-fluorochalcone oxide, TSO, CSO and trans-chalcone oxide at a level of 10^-4M. Microsomal EH was considerably induced (4–5-fold) in mites feeding garlic and onion, or ingesting TSO-impregnated filter papers. Other epoxides like CSO, 2,4-dichlorostilbene oxide, methyl chalcone oxide and heptachlor epoxide displayed moderate induction levels (1.4–2.6-fold). Of the toxicants assayed only sodium phenobarbital was a potent inducer. Lindane, malathion and DDT did not stimulate EH activity and 3-methyl-cholanthrene was even inhibitory. A decrease in EH activity was observed with a number of phytochemicals tested such as sinigrin, flavone, menthol, trans--carotene, chalcone, allyl sulphide and trans-cinnamic acid.     

Trophic determinants of hypopus induction in the stored-product mite Lepidoglyphus destructor (Acari: Astigmata)

A unique (synapomorphic) characteristic of astigmatic mites is the heteromorphic deuteronymph also called hypopus. It is a non-feeding and facultative instar between protonymph and tritonymph. The hypopus is adapted for dispersal and sometimes also for dormancy, as in Lepidoglyphus destructor. The experiments reveal a correlation between the composition of the foodstuff, the duration of development of homomorphic instars, the mortality of protonymphs and the production of hypopodes. As food quality decreases, development lasts longer, mortality increases and hypopodes are produced in greater numbers. Disadvantageous trophic conditions of varied chemical nature favour the induction of hypopodes. The experimental data show that hypopus incidences (as percentage individuals of a population) depend on the relative proportions of constituents of an ingested foodstuff. What matters is the ratio between nourishing foodstuff components and those that are of little or no nutritional value. When a certain ratio does not meet a presumed metabolically required level of nutrients a nutritional deficiency results and hypopus induction is triggered, provided that adequate genetic propensities for hypopus production are present (L. destructor is highly polymorphic for hypopus production). Specific key substances are apparently not involved, and composite properties of a foodstuff are crucial for hypopus induction. Decrease of food quality (not poor food per se) during the hypopus-inducible period (late larval to early protonymphal phase) promotes hypopus induction. The interpretation matches the ecological scene. When trophic deterioration of a patch habitat sets in, often as a result of overcrowding, conditions will eventually become untenable. As a response to incurring nutritional deficiencies the mites will induce hypopodes, which provide for escape from or survival at the decaying habitat patch. Experiments support the threshold model of quantitative genetics for hypopus expression as previously inferred from other experiments with L. destructor.     

Four new feather mite species of the genus Proctophyllodes Robin(Astigmata:Proctophyllodidae) from China

Four new species of the feather mite genus Proctophyllodes are described from the birds of the order Passeriformes in China:P.flexuosa sp.nov.from Eophona migratoria Hartert(Chongqing),P.brevis sp.nov.from Passer montanus(Linnaeus)(Anhui and Chongqing),P.garrula sp.nov.from Garrulax poecilorhynchus Gould(Anhui),P.canora sp.nov.from Garrulax canorus(Linnaeus)(Guizhou).