Mating competitiveness and the effect of X-rays and ageing on males of Tetranychus urticae (Acarina, Tetranychidae) in relation to genetic control

Males of Tetranychus urticae Koch were irradiated with X-ray doses of 4, 8, 24 and 32 krad (were applied to 0–1 day-old adult virgin males) and tested in mating competition with one-day-old nonirradiated males. A non-significant excess of parental females were mated to the unirradiated males. This consistent trend in favour of females, mated with unirradiated males was highly significant, when the results of all the experiments were bulked. This indicated that radiation impaired the mating competitiveness of males of T. urticae. Ageing of irradiated males resulted in a significant decrease of male-mating competitiveness at least within 2 days after irradiation. When 24 krad X-rays irradiated males were tested in mating competition at different ages, with unirradiated males of equal age, it was demonstrated that the reduction in mating competitiveness of ageing irradiated males is caused by accelerated agein, due to the irradiation treatment.

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Zusammenfassung Männchen von Tetranychus urticae wurden mit Röntgenstrahlendosen von 4, 8, 24 and 32 krad bestrahlt (angewendet bei 0–1 d alten adulten jungfräulichen Männchen) und in Paarungskonkurrenz mit l-d alten, nicht bestrahlten Männchen getestet. P-Weibchen wurden—nicht signifikant—häufiger von nicht bestrahlten Männchen begattet; dieser durchgängige Trend war jedoch hoch signifikant, wenn die Ergebnisse aller Versuche zusammengefaßt wurden. Dies zeigt an, daß die Bestrahlung die Paarungskonkurrenzfähigkeit der Männchen verschlechtert. Das Altern von bestrahlten Männchen ergab eine signifikante Abnahme der Paarungskonkurrenzfähigkeit, zum mindesten innerhalb von zwei Tagen nach der Bestrahlung. Wurden Männchen nach 24 krad-Röntgenbestrahlung auf Paarungskonkurrenz in verschiedenem Alter, verglichen mit unbestrahlten entsprechenden Alters, getestet, so zeigte sich, daß die Abnahme der Paarungskonkurrenzfähigkeit von alternden bestrahlten Männchen verursacht wird durch beschleunigtes Altern, das durch die Bestrahlung bewirkt wird.

     

Induction of chromosome mutations by X-irradiation in Tetranychus urticae (Tetranychidae) with respect to a possible method of genetic control

Searching for a method of genetic control to eradicate spider mite populations in glass-houses, the possibility of establishing reproductive incompatibility between a mother colony of Tetranychus urticae Koch and derivative subcolonies, due to the induction of chromosome mutations, was investigated. If it is possible to build up complete reproductive incompatibility, males of the chromosome mutation strains can be used to control the original population.It appeared that X-irradiation at a dosage of 2250 r induced a considerable number of chromosome mutations in the sperm of T. urticae. Some of these chromosome mutations were made homozygous, by following a particular crossing-scheme. In this way thirteen different chromosome mutation strains were established. When outcrossing these strains to the original colony the degree of mortality in the haploid F₂ ranged from 53.4 to 92.8%. After outcrossing the various chromosome mutation strains to each other the degree of mortality in the haploid F₂ was between 61.6 and 99.8%. These findings show that in some cases induction of two different chromosome mutations can result in nearly complete reproductive incompatibility.It is not known what sort of chromosome mutations were involved.

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Résumé Recherchant une méthode de lutte génétique, en vue d'éliminer les populations d'acariens dans les serres, on a étudié la possibilité de provoquer une incompatibilité entre géniteurs par irradiation de mâles et sélection dans la descendance d'individus suspectés d'être porteurs de mutations léthales récessives. Il est possible d'aboutir à une incompatibilité complète de la reproduction, des mâles haploïdes porteurs de la mutation pouvant être produits par parthénogenèse arrhénotoque et utilisés pour introduction dans la population d'origine.Il s'est révéle que l'irradiation par rayons X à une dose de 2250 r induit un nombre considérable de mutations dans les spermatozoïdes de Tetranychus urticae. Quelques-unes de ces mutations chromosomiques furent obtenues à l'état homozygote en adoptant un schéma particulier de croisements. De cette façon 13 lignées portant des mutations chromosomiques différentes ont été obtenues. Quand on croise ces lignées avec la colonie d'origine le degré de mortalité dans la descendance haploïde en F² est de 53.4 à 92.8%. Après avoir réalisé une série de croisements entre les diverses lignées mutantes, le degré de mortalité en F² a atteint 61.6 à 99.8%. Ces résultats montrent que dans quelques cas l'induction de deux mutations chromosomiques différentes peut avoir pour conséquence une incompatibilité génétique presque totale dans la reproduction.On ne sait pas quelle sorte de mutations chromosomiques sont en cause.

     

Toxicity and anticholinesterase activity of carbamates towards the mite Tetranychus urticae

Contact toxicity of three carbamates to a susceptible and an organophosphate resistant strain of T. urticae was determined by topical application. Temik was more toxic than Tranid or paraoxon, and carbaryl was non-toxic. The 10 X paraoxon resistant strain was 2 X and 3 X cross-resistant to Temik and Tranid, respectively. The inhibition and recovery rates of erythrocyte and susceptible mite ChE were determined for the three carbamates.

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Zusammenfassung Die Kontaktgiftwirkung von 3 Carbamaten gegenüber einem anfälligen und einem organophosphatresistenten Stamm von T. urticae wurde durch topische Applikation bestimmt. Temik war giftiger als Tranid oder Paraoxon, und Carbaryl war ungiftig. Der 10fach paraoxon-resistante Stamm war gegenüber Temik und Tranid 2- bzw. 3fach resistent. Für die 3 Carbamate wurden Hemmung und Erholungsraten der Erythrocyten und der Cholinesterase der anfälligen Milben bestimmt.

     

Geographic variations and combining abilities in the two-spotted spider mite, Tetranychus urticae

Geographic variations and combining abilities of three fitness traits: the mean number of offspring, and the mean number and proportion of female offspring, in the two-spotted spider mite were investigated using four widely separated strains of Tetranychus urticae Koch. Analyses of data obtained from a complete set of diallel crosses, involving the four strains, revealed large and highly significant specific combining abilities and reciprocal effects in all the fitness characteristics examined. It was concluded that the whole chain of reproductive events, from egg production of parental females to the fertility of hybrid daughters could be severely affected by incompatibility between parental populations.

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Résumé L'étude a porté sur les différences géographiques et les combinaisons de trois caractères adaptatifs—nombre moyen de descendants, nombre moyen et proportion de femelles dans la descendance—sur quatre souches différentes de Tetranychus urticae. L'analyse des données obtenues à partir d'un lot complet de croisements dialléliques, sur les quatre souches, révèle pour tous les caractères adaptatifs examinés une forte aptitude à l'association et aux effets réciproques. On peut en conclure que la chaîne totale des événements intervenant dans la reproduction—de la production d'oeufs par les mères jusqu'à la fécondité des filles hybrides—pourrait être fortement modifiée par l'incompatibilité entre populations parentales.

     

Male lures and male mating competitiveness in a genetic sexing strain of the melon fly (Diptera: Tephritidae)

The Sterile Insect Technique (SIT) has been used to suppress or eradicate populations of the melon fly, Zeugodacus cucurbitae (Coquillett), a pest of various fruits and vegetables throughout Asia, Africa, and South Pacific Islands. The success of the SIT depends largely on the ability of released, sterile males to compete successfully with wild males for copulations with wild females. Unfortunately, both the sterilization process (via gamma irradiation) and artificial selection under mass-rearing conditions generally reduce the biological competence, including the mating competitiveness, of the released males. However, previous data on Z. cucurbitae show that irradiation has minimal adverse effects and prolonged mass-rearing may or may not result in decreased mating ability. The present study first confirms that neither irradiation nor mass-rearing had deleterious effects on male mating ability of males from a pupal-color, genetic sexing strain (termed T1). Then, the influence of male lures (cue-lure and its natural analogue raspberry ketone) on the mating success of sterile T1 males was measured as a potential pre-release procedure to improve the effectiveness of SIT. Feeding on cue-lure enhanced male mating success, but the effect was short-lived (1 d but not 3 d post-feeding). Feeding on raspberry ketone boosted mating success over a longer time, i.e., at least 5 d but not 10 d post-feeding. However, mixing raspberry ketone into the adult diet had no detectable effect on male mating performance. The implications of these results for SIT against Z. cucurbitae are discussed.     

Genetic variability of photoperiodic response in an arrhenotokous mite (Tetranychus urticae)

Starting with a population of Tetranychus urticae, a number of lines were inbred by sibmating for seven generations. When these inbred lines were exposed to different photoperiodic regimens, a diversity of response curves was obtained. This indicated that great genetic variability of photoperiodic response existed in the original colony.From reciprocal mass-crosses between one line, characterized by a low level response (LR), and several lines which showed a nearly saturated photoperiodic response (HR), it was concluded that HR was dominant over LR. From a study of the backcrosses to LR-males, it appeared that the transmission of the character was different in the two types of F₁-hybrids. The difference could be explained by assuming a cytoplasmic determinant. The possibility that the difference in inheritance resulted from a peculiar haplo-diploid sex-determination was also considered.

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Zusammenfassung Von einer Wildpopulation der Spinnmilbe Tetranychus urticae von Sambucus ausgehend, wurden durch Geschwisterpaarung über 7 Generationen eine Anzahl Inzucht-Linien gezüchtet. Wenn diese Inzucht-Linien verschiedenen Tageslängen ausgesetzt wurden, ergaben sich unterschiedliche photoperiodische Wirkungskurven bezüglich der Diapause-Reaktion. Diese weisen auf das Vorhandensein einer großen genetischen Variabilität in der photoperiodischen Reaktion der Ausgangspopulation hin.Aus reziproken Massenkreuzungen zwischen einer durch einen niedrigen Reaktionsspiegel (LR) gekennzeichneten Linie mit verschiedenen Linien mit hahezu vollständiger, photoperiodisch bedingter Diapause-Reaktion (HR) wird geschlossen, daß HR (hohe Diapause-Auslösung) über LR (schwache Diapause-Auslösung) dominant ist. Aus einer Untersuchung von Rückkreuzungen der weiblichen Hybriden mit LR-Männchen ergibt sich, daß die Weitergabe der Reaktionseigenschaft bei den beiden Typen der F₁-Bastarde (HR x LR bzw. LR x HR) anscheinend verschieden ist. Der Unterschied könnte mit der Annahme eines cytoplasmatischen Vererbungsfaktors erklärt werden. Doch wird auch die Möglichkeit erwogen, daß der Unterschied im Erbgang durch die Besonderheit einer geschlechtsgebundenen haplo-diploiden Vererbung bedingt sei.

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The study is a part of an International Biological Programme Project in the Netherlands.     

The Effects of Clofentezine on Life-table Parameters in Two-spotted Spider Mite Tetranychus urticae

Sublethal effects of the growth inhibitor, clofentezine, on life-table parameters of Tetranychus urticae Koch females treated at different developmental stages with a concentration causing ≥90% mortality were investigated. Females which survived treatment as ‘early’ (0–24 h old) eggs produced 12% more offspring than the untreated females during the first five days of oviposition. This resulted in a significant rise in the intrinsic rate of increase (r _j ): 0.324, compared to 0.299 in the untreated females. This effect may be interpreted as hormoligosis. Clofentezine treatment at any other developmental stage of T. urticae significantly decreased both longevity and fertility of female survivors. Females which survived treatment either as ‘late’ (72–96 h old) eggs or larvae had 2.6 times lower net reproductive rate (R ₀) than the untreated females, and the r _j values were significantly lower: 0.242 and 0.215, respectively (0.285 in the untreated females). Females which survived treatment either as protonymphs or deutonymphs had 3.9 times and 6 times lower R ₀, respectively. Corresponding r _j values were 0.178 and 0.146, respectively (0.247 in the untreated females). The clofentezine treatment at all stages influenced the age distribution of survivors. The sublethal effects of clofentezine and their impact on T. urticae management are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Movement of the twospotted spider mite, Tetranychus urticae, among hosts in a corn-peanut agroecosystem

A 3 year study of spider mites in a corn-peanut agroecosystem indicated that the persistance and pest status of mite populations depended on dispersal among a succession of temporarily suitable cultivated and non-cultivated hosts. In the spring, mites crawled from overwintering sites in vegetation along field margins into both peanut and corn fields, but became established only in corn. Initiation of aerial dispersal from corn was coincident with and appeared dependent upon mites moving to the top of the corn canopy, where they were exposed to the wind. Mites were first observed in peanut immediately following the onset of aerial dispersal from corn, and these aerial dispersers were the primary source of subsequent mite infestations in peanut. As populations grew in peanut, mites dispersed into vegetation along peanut field margins and became the nucleus of populations which persisted over the winter. This pattern of host utilization was reinitiated in the spring if corn was planted adjacent to infested field borders. This pattern commonly occurs since corn is planted following peanut in the predominant crop rotation sequence in this area.

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Résumé Des populations d'acariens ont été étudiées pendant 3 ans sur maïs, arachide et végétation spontanée, dans 7 fermes commerciales de Chowan Co., Caroline du Nord. Les déplacements d'acariens parmi ces plantes ont été notés en fonction de la croissance de la population et de la phénologie des hôtes. Un schéma cohérent de croissance de la population d'acariens et de leurs mouvements en découle, dont seule la taille change suivant les fermes et les années. Les acariens provenant de populations hivernantes sur la végétation spontanée bordant les champs migrèrent dans les champs cultivés adjacents quelle qu'en soit la nature de la culture. Cependant, à cette époque, les populations d'acariens ne s'établissaient que dans le maïs. Dans le maïs, les acariens se répandirent à travers le champ et se multiplièrent sur des pieds particuliers jusqu'à ce qu'ils eussent atteint le sommet de la canopée du maïs. Les premiers acariens transportés par le vent ont été capturés la semaine suivant la première apparition d'acariens au sommet de la canopée du maïs et aussitôt après la découverte des premiers acariens dans les arachides voisines. Ceci suggère que les acariens dispersés par le vent sont à l'origine des contaminations ultérieures des arachides voisines. Plus tard dans la saison, les acariens se dispersèrent à partir de l'arachide vers les sites d'hibernation dans la végétation spontanée poussant autour du champ d'arachide. Puisque des champs semés en arachides sont généralement semés en maïs l'année suivante, les acariens se dispersant au printemps depuis les sites d'hibernation rencontrèrent souvent du maïs qu'ils colonisèrent. Ce cycle répétitif d'utilisation de l'hôte et de dispersion est considéré comme fortement responsable de la pérennité des acariens et de leur danger potentiel dans les agroécosystèmes à maïs-arachide, caractéristiques du canton de Chowan (N.C.).Les problèmes potentiels posés par les acariens sur arachide ont paru être liés à l'intensité de l'attaque d'acariens sur le maïs voisin, qui sert de réservoir pour les populations d'acariens. Ceci suggère que le contrôle des populations d'acariens sur maïs peut être une stratégie viable pour limiter les infestations ultérieures sur arachide et, en dernier lieu, les populations hivernantes.

     

Population response of the twospotted spider mite,Tetranychus urticae, to host phenology in corn and peanut

In northeastern North Carolina, outbreaks ofTetranychus urticae Koch on commercial corn and peanut plantings were observed to coincide with flowering and fruiting of the crop host. In greenhouse studies, when equal mite numbers were started on plants in either vegetative or reproductive growth stages, populations increased significantly more after 3–4 weeks on reproductive plants of both corn and peanut. This direct response of mite populations to differences in plant phenology appears to be an important component in the population dynamics ofT. urticae. The importance of this effect in understanding mite outbreaks on corn and peanut is discussed, especially in reference to the corn-peanut agroecosystem in North Carolina.

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Réponse de populations deTetranychus urticae Koch., aux phénologies du maïs et de l'arachide

Résumé Les populations de tétraniques sont souvent associées à la floraison et à la fructification des plantes attaquées. Dans les agrosystèmes maïsarachide du N.E. de la Caroline du Nord, l'augmentation rapide de populations deT. urticae a été observée lors de la maturation des épis mâles du maïs et du maximum de floraison de l'arachide. Bien que ces observations suggèrent une relation causale avec la phénologie des plantes hôtes, il est difficile de déterminer dans les conditions de la nature si l'augmentation des populations d'acariens sur les stades reproducteurs des plantes est due à une réponse à la phénologie des cultures ou à une autre cause, comme le passé de la population ou une immigration. Des expériences ont été réalisées dans une serre pour mettre en évidence l'action de la phénologie du maïs et de l'arachide sur les populations d'acariens en maîtrisant ces autres hypothétiques facteurs. Des effectifs identiques d'acariens femelles ont été libérés sur des plantes à des stades tant végétatifs que reproductifs, et ensuite laissés sans interventions pendant plusieurs semaines, au bout desquelles les effectifs sur chaque plante ont été dénombrés. Sur les deux hôtes, les populations sur plante à un stade reproducteur avaient augmenté significativement plus que sur les plantes de même espèce à un stade végétatif. Ces résultats montrent queT. urticae répond directement à des différences entre plantes à un stade végétatif et à un stade reproductif. Cette réponse semble jouer un rôle important dans la dynamique des populations deT. urticae.

     

Genetic affinities between spider mite Tetranychus urticae (Acarina: Tetranychidae) populations in a non-agricultural area

Partial reproductive incompatibility between spider mite populations from adjacent glasshouses is a common phenomenon. It is demonstrated that such a multitude of incompatibilities is not found outdoors between populations collected from ground-ivy (Glechoma hederacea) growing in a dune area on the west coast of the Netherlands.

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Zusammenfassung Eine partielle reproduktive Unverträglichkeit zwischen Spinnmilbenpopulationen benachbarter Glashäuser ist eine häufige Erscheinung. Es wurden Untersuchungen unternommen um abzuklären, ob in einer verhältnismässig ungestörten nichtlandwirtschaftlichen Gegend eine ähnliche Situation existiert. 48 Stämme von Tetranychus urticae wurden auf Gundelrebe, Glechoma hederacea, gesammelt, welche in 5 Lokalitäten einer Dünengegend der holländischen Westküste wuchsen. Zwischen diesen Stämmen wurden Kreuzungen in 89 Kombinationen durchgeführt. Die F₂-Eimortalität lag meist unter 15% und war im Durchschnitt um 9% (Tabelle I). Die Kontrollwerte (Tabelle I, Gruppe III) waren nicht signifikant tiefer. Dies ist in auffälligem Gegensatz mit den Untersuchungen, welche durchgeführt wurden mit Spinnmilbenpopulationen eines Glashauskomplexes, der eine ähnlich grosse Fläche bedeckt (Helle & Pieterse 1965, Overmeer & Van Zon, 1976).

     

Host race formation inTetranychus urticae: genetic differentiation, host plant preference, and mate choice in a tomato and a cucumber strain

The two-spotted spider mite,Tetranychus urticae Koch, occurs in two colour forms in greenhouses in the Netherlands: a red form on tomato and a green form on cucumber. The evolutionary status of these strains was analysed by studying genetic differentiation, host plant preference, and mate choice. Males of the tomato strain preferred the female (30 h-old) teleiochrysales from the same strain to those of the cucumber strain, independent of the host plants (tomato, cucumber, bean) on which the teleiochrysales were placed. In contrast, males of the cucumber strain were not selective. In a Y-tube olfactometer, females of the cucumber strain were not responsive to host plant volatiles alone. However, in two-choice disc experiments, where females were exposed to both volatile and contact cues, they settled on cucumber leaves in preference to tomato leaves. Females of the tomato strain preferred the odour of tomato leaves and settled on tomato leaves in preference to cucumber leaves. These experimental results provide the first evidence for (1) host-plant independent mate selection in male spider mites and (2) olfactory discrimination between host plants in female spider mites. Electrophoretic analysis showed much genetic differentiation at the phosphoglucose isomerase locus. The cucumber strain showed large variation with 5 alleles, whereas the tomato strain was fixed for the most common allele of the cucumber strain. The results suggest that the two strains represent host races. We hypothesize that the tomato strain has originated from the cucumber strain because (1) tomato represents a more hostile host plant to spider mites (due to toxic compounds and glandular hairs) and (2) the tomato strain is genetically impoverished suggesting that it passed through one or more bottlenecks.     

丁氟螨酯对二斑叶螨生长发育的影响

[目的]丁氟螨酯是一种新型酰基乙腈类非内吸性杀螨剂,对害螨的各个螨态都有很高活性,具有较高的应用价值.本文评价了丁氟螨酯对二斑叶螨生长发育的影响,以期为合理用药和二斑叶螨的综合防治提供理论依据.[方法]采用浸叶法测定丁氟螨酯对二斑叶螨成螨与卵的致死中浓度、雌成螨产卵量、各螨态存活率以及各发育历期的影响.[结果]经丁氟螨...     

Colonization of a hybrid strain to restore male Anastrepha ludens (Diptera: Tephritidae) mating competitiveness for sterile insect technique programs

To restore male mating competitiveness of Mexican fruit flies, Anastrepha ludens (Loew) (Diptera: Tephritidae), reared for sterile insect releases by the Mexican Fruit fly Eradication Campaign, two strain replacement techniques were evaluated. Field cage male competitiveness tests revealed that laboratory males of the Metapa strain mated 3 times less often with wild females than field-collected wild males. A strain developed from the cross of wild males and laboratory females (hybrid strain) was similar to a strain developed from the cross of laboratory males and females (laboratory strain) in that its females produced similar amounts of eggs and the eggs displayed similar levels of hatch and egg-to-pupa transformation in artificial diet. By contrast, a strain developed from the cross of wild males and females (wild strain), forced into artificial rearing, experienced a series of bottlenecks involving reduced egg laying and extremely poor development in diet. The male F1 progeny of the hybrid strain and field-collected wild males outcompeted Fl laboratory males in field cage tests for matings with field-collected wild females. In conclusion, we found that strains developed from the cross of wild males and laboratory females allowed us to restore male mating competitiveness of F1 Mexican fruit flies without compromising mass-rearing production.     

Acclimation of chloroplast transglutaminase to high NaClconcentration in a polyamine-deficient variant strain of Dunaliella salina and in its wild type

The wild type (Wt) and the polyamine-deficient strain (PA⁻vs) of the halotolerant Dunaliella salina were subjected to stress caused by 3.5 mol/L NaCl concentration. The chloroplasts were isolated and the molecular aspects of their reaction to salt stress were studied together with their recovery response to these hyper-saline conditions.In the Wt, the photosynthetic complexes were found to be severely affected by salt stress under light conditions. Transglutaminases, which are present in chloroplasts as two units of 25 and 50 kDa, were immunorecognized by antibodies raised against rat prostatic gland transglutaminase. The amount, in particular that of the 50 kDa unit, underwent an immediate change following hyper-saline stress. These concentration changes were found to coincide with variations in enzymic activity, which is also affected by the presence or absence of light.The PA⁻vs has a concentration of proteins and chlorophylls which is much lower than that of the Wt. In addition, the PA⁻vs appeared to be more severely affected by both salt and subculture stresses. Its recovery time was also longer. Its TGase activity increased after salt stress and was always higher in the light than in the dark, except soon after subculture, showing an additive stress effect of salt and light. In the PA⁻vs acclimated to high salinity, or immediately after stress application, the chloroplast content of chlorophyll a and b was considerably enhanced, like the TGase activity (by two-fold or more), and these changes exhibited almost coincident behaviours.Some transglutaminase substrates (proteins of 68, 55, 29 and 27 kDa) were found to be similar to those present in higher plants (thylakoid photosynthetic complexes and Rubisco). They were more markedly labelled by [1,4-¹⁴C] polyamines when the transglutaminase assay was performed in the light than in the dark, and much more in algae already acclimated to hyper-saline conditions than in those cultured in the optimal saline medium, or subjected to stress. The amount of 68 and 55 kDa polypeptides was particularly high in the 3.5 mol/L NaCl acclimated cells. The possible role of polyamine conjugation in the assembly of chloroplast proteins in cells affected by salt stress is discussed.     

Microbial diversity in the predatory mite Metaseiulus occidentalis (Acari: Phytoseiidae) and its prey, Tetranychus urticae (Acari: Tetranychidae)

Microorganisms associated with the predatory mite Metaseiulus (=Typhlodromus or Galendromus) occidentalis (Nesbitt) and its prey, the two-spotted spider mite Tetranychus urticae (Koch), were assessed using a high-fidelity polymerase chain reaction (PCR) protocol and primers designed to identify Eubacteria, Archaeabacteria, iridoviruses, Helicosporidia, Cytophaga-like microorganisms, Wolbachia and its bacteriophage WO, fungi and yeast-like organisms. Sequences from four bacterial species related to Wolbachia (α-Proteobacteria), Cardinium, Bacteroidetes, and Enterobacter (γ-Proteobacteria) were obtained from M. occidentalis, and three sequences related to Wolbachia, Rickettsia, and Caulobacter (α-Proteobacteria) were obtained from T. urticae. No nucleotide differences were detected between the 16S rRNA, wspA or wspB Wolbachia sequences obtained from M. occidentalis and T. urticae, which suggest that horizontal transfer of Wolbachia could have occurred. Southern blot analyses of genomic DNA from both M. occidentalis and T. urticae using wspA probes were negative, indicating that this Wolbachia sequence is not integrated into the nuclear genome of either species. Two of the T. urticae colonies tested contained the WO bacteriophage, but none of the six M. occidentalis populations were infected. New M. occidentalis-specific forward and reverse 16S rRNA primers based on the Wolbachia, Cardinium, Bacteroidetes, and Enterobacter sequences obtained were designed and used to amplify PCR products from each of two laboratory and four field-collected samples of M. occidentalis females and eggs, indicating that these infections are widespread. Likewise, species-specific primers for T. urticae were designed for the Wolbachia, Rickettsia, and Caulobacter sequences obtained and used to evaluate T. urticae from strawberries, wine grapes, hops, almonds, and cherries from California, Washington, and Florida; all were positive for Wolbachia and Caulobacter but two of the six were negative for Rickettsia. None of the M. occidentalis colonies tested were positive for the microsporidium Oligosporidium occidentalis, which previously had been associated with a pathogenic condition in some of our laboratory colonies. The Gainesville colonies of M. occidentalis and T. urticae were negative for iridovirus, Archaeabacteria, fungi, Helicosporidia, and yeast-like organisms. So far, Wolbachia is the only symbiont that is shared by this predator and its prey.     

一个蚕豆病遗传家系G6PD基因突变及X染色体失活偏移检测

对一蚕豆病遗传家系的G6PD基因突变进行分析,检测突变后G6PD酶活变化,并对先证者家系进行X染色体失活（XCI）偏移模式检测,从而预测G6PD突变女性携带者患蚕豆病的风险。取家系成员的外周血样,并提取基因组DNA,用聚合酶链式反应（PCR）和DNA测序法进行序列分析,确定先证者突变位点和突变类型及家庭成员遗传情况,若先证者的母亲和姐姐为G6PD突变携带者,则对先证者母亲和姐姐进行X染色体偏移检测以及酶活检测分析,以评估携带者患蚕豆病的风险,同时对研究对象进行随访。结果患者X染色体上G6PD基因发生点突变c.1376G>T;酶活性检测结果显示该突变使G6PD酶活性下降大约25%,导致蚕豆病发生。该家系的两位女性携带者X染色体失活偏移<80%,未来发生蚕豆病的可能性低。     

Rates of spontaneous mutation in certain genes of an arrhenotokous mite, Tetranychus pacificus

A number of 25.000 haploid males of Tetranychus pacificus was examined for the occurrence of mutations in certain genes for pigmentation. The spontaneous mutation rate in the six chosen genes p, al, we, w, le and st appeared to lie between 0.8×10^-4 and 2.8×10^-4. This high mutation rate is discussed in relation to the adaptational potentiality of the population, particularly with respect to insecticide resistance.

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Spontane mutationsraten bei gewissen gene der arrhenotoken milbe Tetranychus pacificus

Zusammenfassung 25000 haploide Männchen von Tetranychus pacificus wurden auf das Auftreten von Mutationen bei bestimmten Farbgenen geprüft. Die spontane Mutationsrate schien bei den Genen p, al, we, w, le und st zwischen 8×10^-4 und 2.8×10^-4 zu liegen. Diese hohe Mutationsrate wird im Hinblick auf die Anpassungsfähigkeit der Population besonders bezüglich der Insektizidresistenz diskutiert.

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The investigation is part of a study granted by the Shell Prize for Biology in the Netherlands.     

A dominant mutation (SAD) bypassing the requirement for the a mating type locus in yeast sporulation

Summary SAD (suppressor of a deficiencies) is a mutation that allows -mater diploids such as / or a1^-/ strains to sporulate. This mutation is unstable and reverts to wildtype (sad ⁺) even in strains homozygous for SAD. SAD is dominant to sad ⁺: / and a1^-/ sad ¹/SAD diploids are sporulation-proficient. SAD is located on chromosome III, 40 cM distal to the mating type locus, between THR4 and HMR a. The ability of SAD to support sporulation requires the presence of an mating type locus with an active 2 function. Possible models for the action of SAD are (1) SAD bypasses the need for a1 function in sporulation, and (2) SAD provides a1 function to MAT a1^- mutants by supplying a1 function itself, for example, by allowing expression of a silent copy of MAT a.     

Expression of A mating type genes of Coprinus cinereus in a heterologous basidiomycete host

The A mating factor of Coprinus cinereus determines compatibility in mating by regulating part of a developmental sequence that leads to dikaryon formation. The A genes that trigger development encode two different classes of homeodomain proteins, and for a successful mating, a protein of one class, HD 1, must interact with a protein of the other class, HD 2. In this report we show that C. cinereus A genes that encode HD 2 proteins, a2-1 and b2-1, can elicit A-regulated development in the heterologous host C. bilanatus. Transformation rates were very low, suggesting that the genes were poorly transcribed. The fact that the HD 2 genes are functionally expressed implies successful heteromultimeric association of putative DNA-binding proteins coded by the two Coprinus species. This interaction was sufficient to satisfy the need for different A factors in the formation of a fertile C. bilanatus dikaryon, but fertile dikaryons were more readily produced in matings with the a2-1 gene transformants. The C. cinereus A genes, b1-1 and d1-1, which encode HD1 proteins, were either not expressed or their proteins were non-functional in C. bilanatus. These experiments raise some interesting questions regarding HD1–HD2 protein interactions.