Observations on a mite (Poecilochirus davydovae) predatory on the eggs of burying beetles (Nicrophorus vespilloides) with a review of its taxonomic status

Observational evidence is presented suggesting that the mite Poecilochirus davydovae Hyatt (Mesostigmata: Parasitidae) is predatory on the eggs of the burying beetle Nicrophorus vespilloides Herbst and that an increase in numbers of the mite in the laboratory accounts for a reduction in apparent beetle clutch size over successive generations. Morphological adaptations for oophagy are described and physogastry is reported for the first time in the genus Poecilochirus. A new sub-genus Physoparasilus is proposed for the reception of P. davydovae and P. subterraneus and the female of P. davydovae is redescribed. The implications of the oophagous behaviour of P. davydovae on the mite-Nicrophorus relationship are discussed.     

The dispersal behaviour of the phoretic mite Poecilochirus carabi (Mesostigmata,Parasitidae): adaptation to the breeding biology of its carrier Necrophorus vespilloides (Coleoptera,Silphidae)

Summary When the phoretic mite Poecilochirus carabi reproduces in the brood chamber of its carrier Necrophorus vespilloides, a beetle with biparental brood care, the first deuteronymphs of the new mite generation aggregate on the male beetle. They do not use sex-specific traits to discriminate between male and female beetles in the brood chamber, but traits that are related to the beetles' behaviour and may be displayed by both parent beetles. When the male beetle departs, it carries virtually all deuteronymphs then present in the brood chamber. Deuteronymphs that develop later congregate on the female, which leaves the crypt some days after the male. Only those deuteronymphs that miss the female's departure disperse on the beetle larvae, meaning they have to wait in their pupal chambers until the beetles have completed their development. On average, 86% of the deuteronymphs leave the brood chamber on the parent beetles, thereby gaining the advantage of an early departure. As soon as their carrier arrives at one of the beetles' meeting places, the deuteronymphs can transfer between the beetles present. Choice experiments revealed that the deuteronymphs tend to even out density differences between congregating carriers, and prefer sexually mature to immature beetles. Therefore, transferring between beetles results in a dispersion of deuteronymphs on the sexually mature beetles of the population.     

Digestion in the soil predatory mite Pergamasus longicornis (Berlese) (Acari: Mesostigmata: Parasitidae)--detectable hydrolases

Nineteen hydrolytic enzymes were detected in individual adult Pergamasus longicornis (Berlese) mites--amylase, hide protease, alkali phosphatase, esterase (C4), esterase lipase (C8), lipase (C14), leucine arylamidase, valine arylamidase, cystine arylamidase, acid phosphatase, phosphoamidase, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, beta-glucosidase, N-acetyl-beta-glucosaminidase, alpha-mannosidase, and alpha-fucosidase. All but the phosphatases were detected for the first time. Tryptic and chymotryptic activity were consistently not demonstrable. Comparisons are made with saprophagous mites. No clear enzymic specialization for predation was found.     

Morphological differences between sympatric populations of the Poecilochirus carabi complex (Acari: Mesostigmata: Parasitidae) associated with burying beetles (Silphidae: Nicrophorus)

Adults of two sympatric populations of the parasitid mite Poecilochirus carabi G. & R. Canestrini, one preferring Nicrophorus vespillo (Linnaeus) as carrier beetle species and the other N. vespilloides Herbst, could be separated by differences in the form of the structures associated with the male genital orifice and the size of the female endogynum. Adults and deuteronymphs of the two populations also differed in the size of idiosomal shields and dorsal setae. On the basis of these findings, plus data from a literature review and an examination of type-material, the preference type choosing N. vespilloides was identified as P. carabi (sensu stricto) and that preferring N. vespillo as P. necrophori Vitzthum, a species previously synonymised with P. carabi.     

Gut expansion and contraction in the predatory soil mite Pergamasus longicornis (Mesostigmata: Parasitidae): a stiff system

Mite digestive processes are inferred from gut expansion and contraction time in the free-living predatory soil mite Pergamasus longicornis (Berlese), estimated using a temporal series of histological sections. Gut regions (bar the rectal vesicle) behave broadly in unison for rapid initial filling (ingestion half-life about 2–3 min; max 8 min), but behave heterogeneously when slowly emptying (digestion/egestion half-life from about 2–3 h; max 8.5 h). Anterior gut regions fill and empty the earliest. Posterior gut regions take the longest to fill and to empty. Switching first from filling-predominating to emptying-predominating in the gut occurs around 2 h from the start of feeding. Median time for the initial completion of gut filling and for the commencement of gut emptying is 10 min and 12.5 h, respectively, from the start of feeding. Three phases of gut changes are critically discussed: rapid filling, concentration by fluid loss (via coxal glands), and slow emptying. Independent corroboration of coxal droplet formation is included. Predictions to confirm or refute postulated mechanisms of salivary, coxal or rectal water balance are given. Overall total gut filling (ingestion) plus gut emptying (digestion/egestion) time in this poikilotherm is approximately 29–52.5 h ( \(1^{+}-2^{+}\) days) at room temperature from the start of feeding on large dipteran prey ( \(\equiv 0.46-0.83\) gut emptyings per day). Pergamasus longicornis exhibits the stiff digestive system of an intermittent ‘bolus’ feeder.     

Occurrence of Poecilochirus austroasiaticus (Acari: Parasitidae) in forensic autopsies and its application on postmortem interval estimation

Despite the fact that mites were used at the dawn of forensic entomology to elucidate the postmortem interval, their use in current cases remains quite low for procedural reasons such as inadequate taxonomic knowledge. A special interest is focused on the phoretic stages of some mite species, because the phoront-host specificity allows us to deduce in many occasions the presence of the carrier (usually Diptera or Coleoptera) although it has not been seen in the sampling performed in situ or in the autopsy room. In this article, we describe two cases where Poecilochirus austroasiaticus Vitzthum (Acari: Parasitidae) was sampled in the autopsy room. In the first case, we could sample the host, Thanatophilus ruficornis (Küster) (Coleoptera: Silphidae), which was still carrying phoretic stages of the mite on the body. That attachment allowed, by observing starvation/feeding periods as a function of the digestive tract filling, the establishment of chronological cycles of phoretic behavior, showing maximum peaks of phoronts during arrival and departure from the corpse and the lowest values in the phase of host feeding. From the sarcosaprophagous fauna, we were able to determine in this case a minimum postmortem interval of 10 days. In the second case, we found no Silphidae at the place where the corpse was found or at the autopsy, but a postmortem interval of 13 days could be established by the high specificity of this interspecific relationship and the departure from the corpse of this family of Coleoptera.     

新革螨属2新种记述（蜱螨亚纲：中气门目：寄螨科）

记述新革螨属2新种：双锯新革螨Neogamasus biserrendogynii sp．nov．和双瓣新革螨Neogamasus bivalvendogynii sp．nov．。     

Studies of the protein content of individualPergamasus longicornis (Berlese) (Acari: Mesostigmata: Parasitidae)

The protein content ofPergamasus longicornis (Berlese) individuals is of the order of 45 g bovine serum albumen equivalents and varies depending on gender, time of year and gut colour (postulated nutritive state). Variation between males and females closely matches their size difference. A sinusoidal relationship with a late spring/early summer maximum and a late autumn/early winter minimum is shown for females. Gut colour is a useful predictor in females only. Pregnancy and prey utilisation over the year are suggested as important determinants of protein content and are discussed in detail.     

卷须偏革螨在中国大陆的发现（蜱螨亚纲：中气门目：寄螨科）

报道卷须偏革螨Pergamasus pampinatus Tseng,1995在中国大陆的发现.     

Oviposition behaviour of the soil mite Pergamasus brevicornis (Acari: Parasitidae)

We observed the oviposition behaviour of the soil mite Pergamasus brevicornis Berlese (Acari: Parasitidae) using continuous video-monitoring. Oviposition consisted of six sequential phases. The first phase (I) involved inspection of the substrate. In the second phase (II) there were rhythmic movements of the first pair of legs and slight reciprocating movements of the body. The third (III) was a resting phase. In the fourth phase (IV) the gnathosoma was lowered and the body was raised. In the next phase (V) there were two sub-phases. During the first (Va), the female held the egg below the gnathosoma. In the second sub-phase (Vb), the gnathosoma moved up holding the egg, which was then placed on the substrate. The last phase (VI) involved intense ‘cleaning’ movements of the chelicerae and palps. During Va a protective external eggshell structure is gradually formed, involving a phase where the egg shell is sticky. After moving the egg to the substrate, the female freed her palps and chelicerae from the sticky egg shell and cleaned her gnathosomal appendages. Phases II–V took on average 207 ± 69 s.     

鹿角新革螨在中国大陆的发现(蜱螨亚纲:中气门目:寄螨科)

报道寄螨科1种螨在中国大陆的发现:鹿角新革螨Neogamasus cervicornis(Van Daele,1975)。     

为拟月角革螨另立新名及中国北方异肢螨属研究(蜱螨亚纲:革螨股:寄螨科)

为拟月角革螨另立新名为欧拉角革螨Cornigamasus oul aensisMa,nom.nov.,并记载中国北方异肢螨属6种,即:地下异肢螨Poecilochirus subterraneus(J.Müller),达氏异肢螨P.davydovae Hyatt,澳亚异肢螨P.austroasiaticus Vitzthum,卡拉毕异肢螨P.carabiG.etR.Canestrini,埋异肢螨P.necrophori Vitzthum,特雷异肢螨P.trebinjensis Willmann。列有检索表并绘图,以供鉴别。     

Studies on feeding in the soil predatory mitePergamasus longicornis (Berlese) (Mesostigmata: Parasitidae) using dipteran and microarthropod prey

Larvae ofMusca domestica andDrosophila melanogaster were tested as prey for adultPergamasus longicornis using soil microarthropods as controls. Fly larvae were fed upon for a longer time and almost continuously. Second-instar larvae ofM. domestica were not eaten completely. No differences were detected between the sexes of the predator. Final-instar larvae ofD. melanogaster were chosen for subsequent experimentation. New field records of soil prey are included.     

寄螨属1新种和常革螨属1新种(蜱螨亚纲:中气门目:寄螨科)

记述寄螨科2新种：豫寄螨Parasitus yuensis Ma et Lin,sp．nov．和云南常革螨Vulgarogamasus yunnanensis Maet Zhang,sp．nov．。     

Laboratory studies of predation by the Antarctic mite Gamasellus racovitzai (Acarina: Mesostigmata)

Summary Laboratory investigations of predation by Gamasellus racovitzai (Acarina: Mesostigmata) on Cryptopygus antarcticus (Insecta: Collembola) are described. The predator appeared to search at random, but, when contact with prey had been made, a rapid attack involved looping the forelegs over the prey to hold it whilst the chelicerae moved forward horizontally to puncture the side of the prey. The mean predation rate by deutonymphs, approximately one prey per predator per 12 days, was independent of prey density, but with adults this rate increased to about one prey per predator per 3 days. A study of leg geometry predicted a maximum prey size that could be captured: some experimental evidence suggested that mites selected prey near to this predicted size. The contribution of the laboratory results towards understanding the dynamics of field populations is discussed.     

寄螨属1新种和革索螨属1新种(蜱螨亚纲:中气门目:寄螨科)

记述寄螨属1新种:简单寄螨Parasitus simplendogynii sp.nov.和革索螨属1新种:泾源革索螨Gamasodes jingyuanensis sp.nov.     

Synganglial and neurosecretory morphology of the chicken mite Dermanyssus gallinae (DeGeer) (Mesostigmata: Dermanyssidae)

Histological techniques and paraldehyde-fuchsin (PAF) staining were used to study the synganglion and to locate neurosecretory regions and neurosecretion within the synganglion of the chicken mite, Dermanyssus gallinae. The synganglion, which is formed internally by neuropilar ganglia, gives rise to a single esophageal and paired cheliceral, palpal, pedal (I-IV), and opisthosomal nerves. The neuropilar ganglia are interconnected by commissures and connectives within the synganglion. Twelve PAF-positive neurosecretory regions are present in unfed protonymphs, unfed deutonymphs, virgin males and females, and mated males. There are 11 PAF-positive neurosecretory regions in larvae, 24–72 hours post-fed deutonymphs and mated females. Neurosecretory regions in these developmental stadia are described in relation to their positions adjacent to individual neuropilar ganglia.     

单角新革螨雌雄螨描述(蜱螨亚纲:革螨股:寄螨科)

单角新革螨 Neogamasus unicornutus ( Ewing,1 90 9)同物异名为岛屿新革螨 Neogamasusislandicus( Sellnick,1 94 0 ) ,其后若螨 [1 ]、前若螨及幼螨 [2 ]已有较详细描述 ,但雌螨和雄螨在所查到的文献中只记载有个别特征 ,没有完整描述 [1 ,3- 6] 。本文根据采自集安的标本 ,描述其雌螨和雄螨。文中测量单位为 μm,括号内为测量均值。单角新革螨 Neogamasusunicornutus(Ewing,190 9)雌螨 (图 1 - 7)体黄色 ,卵圆形 ,长 6 78- 70 1 ( 6 89) ,宽 36 8- 41 4 ( 394 )。背板几乎覆盖整个背面 ,后部留狭窄裸露区。前背板长 345- 356 ( 349) ,…     

新革螨属1新种记述和2已知种若螨描述(蜱螨亚纲:中气门目:寄螨科)

记述新革螨属1新种：拟裂新革螨Neogamasus peribifiditectus sp．nov．。同时对异形新革螨Neogamasus anomalus Ma et Yan,1998和皱形新革螨Neogamasus crispus Ma et Yan,1998若螨进行描述。