Gut contents, digestive half-lives and feeding state prediction in the soil predatory mite Pergamasus longicornis (Mesostigmata: Parasitidae)

Mid- and hind-gut lumenal changes are described in the free-living predatory soil mite Pergamasus longicornis (Berlese) from a time series of histological sections scored during and after feeding on fly larval prey. Three distinct types of tangible material are found in the lumen. Bayesian estimation of the change points in the states of the gut lumenal contents over time is made using a time-homogenous first order Markov model. Exponential processes within the gut exhibit ’stiff’ dynamics. A lumen is present throughout the midgut from 5 min after the start of feeding as the gut rapidly expands. It peaks at about 21.5 h - 1.5 days and persists post-feeding (even when the gut is contracted) up until fasting/starvation commences 10 days post start of feeding. The disappearance of the lumen commences 144 h after the start of feeding. Complete disappearance of the gut lumen make take 5-9 weeks from feeding commencing. Clear watery prey material arrives up to 10 min from the start of feeding - driving gut lumen expansion. Intracellular digestion triggered by maximum gut expansion is indicated. Detectable granular prey material appears in the lumen during the concentrative phase of coxal droplet production and, despite a noticeable collapse around 12 h, lasts in part for 52.5 h. Posterior midgut regions differ slightly from anterior regions in their main prey food dynamics being somewhat faster in processing yet being slightly delayed. Posterior regions are confirmed as Last-In-Last-Out depots, anterior regions confirmed as First-In-First-Out conveyor belt processes. Evidence for differential lability of prey fractions is found. A scheme of granular imbibed prey material being first initially rapidly absorbed (t andfrac12; = 23 min), and also being quickly partly converted to globular material extra-corporeally/extracellularly (t andfrac12; = 36 min) - which then rapidly disappears (t andfrac12; =1.1 h, from a peak around 4 h) is presented. This is then followed by slow intracellular digestion (t andfrac12; = 6.9 h) of the resultant resistant prey residue matching the slow rate of appearance of opaque pre-excretory egestive refractive grains (overall t andfrac12; = 4.5 days). The latter confirmed latent ’catabolic fraction’ (along with Malpighian tubule produced guanine crystals) drives rectal vesicle expansion as ’faeces’ during the later phases of gut emptying/contraction. Catabolic half-lives are of the order of 6.3-7.8 h. Membraneous material is only present in the lumen of the gut in starving mites. No obvious peritrophic membrane was observed. The total feeding cycle time may be slightly over 52.5 h. Full clearance in the gut system of a single meal including egestive and excretory products may take up to 3 weeks. Independent corroborative photographs are included and with posterior predictive densities confirm the physiological sequence of:- ingestion/digestion; egestion; excretion; defecation; together with their timings. Visually dark midguts almost certainly indicate egestive refractive grains (?xanthine) production. Nomograms to diagnose the feeding state of P.longicornis in field samples are presented and show that the timing of these 4 phases in the wild could be inferred by scoring 10-12 mites out of a sample of 20. Suggestions to critically confirm or refute the conclusions are included

Sperm structure in Parasitidae mites (Parasitiformes: Mesostigmata: Gamasina)

Witalinski, W., Podkowa, D. (2016): Sperm structure in Parasitidae mites (Parasitiformes: Mesostigmata: Gamasina). Acarologia 56 (1): 3-32, DOI: 10.1051/acarologia/20162190, URL: http://dx.doi.org/10.1051/acarologia/2016219

Mite species on wild mushrooms on the campus of Ondokuz Mayis University in Samsun, Turkey

International audienc

Evaluation of low humidity treatments to control Acarus farris (Acari: Acaridae) in Cabrales cheese

7 páginas, 1 figura, 1 tabla -- PAGS nros. 243-249Laboratory experiments were conducted to establish the best combination of relative humidity (r.h.) and time of exposure to be applied on Cabrales cheeses infested with Acarus farris. Laboratory assays revealed that less than 30 h were required to obtain 90% mortality of mites at 50% and 60% r.h. Males were more susceptible than females to low relative humidity, since their lethal period values (LP) were lower than those obtained for females at the same relative humidity. Moreover, the response within sexes to low moisture treatments changed as exposure time increased, since the LP50 obtained for each sex at 50 and 60% r.h. were statistically different whereas the LP90 showed no significant differences within sexes. Accordingly, two modifications of the traditional maturing process were established to assess the efficacy of low moisture treatments to control A. farris on infested cheeses. The first modification consisted of one single exposure of 48 h at 50% r.h. and the second one consisted of two exposures of 48 h at 50% r.h. separated by a time interval of 15 days. No significant differences in final population density were observed for both low moisture treatments compared to control cheeses. Therefore, low humidity treatments are not effective to control A. farris in Cabrales cheese, despite the good results obtained in laboratory assaysThe research reported in the present paper was funded by CAPSA and the MCYT (project n. PTR95.0612.OPPeer reviewe