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Acarologia

A quarterly journal of acarology, since 1959Publishing on all aspects of the Acari

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OBSERVATIONS ON ORIBATID MITES IN LABORATORY CULTURES

BY

Gaber lVI. SHEREEF.

Faculty of Biology and Sail Science, Moscow Uuniversity.

This paper sets out a series of observations made on laboratory cultures of a number of ori­batid mites commonly found in the U.S.S.R.

lVIETHODS

Oribatid mites were first reared successfully by MICHAEL (1884) who used small glass cells made by fixing glass rings to microsope slides. GRANDJEAN (1950), CLEAT (1952), SENGBUSCH (1954), PAULY (1956) and HARTENSTEIN (1962) cultured the mites in Stender dishes on a filter paper substratum, while LIPOVSKY et AL (1957) were the first to use a substratum consisting of a mixture of plaster of Paris and charcoal.

In the present investigation individuals representing the species listed in table 1 were kept alive in Petri dishes on a substratum consisting of a mixture of plaster of Paris and charcoal mixed in the ratio 9 : r. Varions fungi were fed to the mites by introducing sections of agar with adherent fungi from pure cultures. The dishes were kept in an incubator at 25°C, and their substratum moistened daily.

For more detailed observations, eggs from the Petri dish cultures were transferred with a fine brush to a plaster of Parisjcharcoal substratum in small glass cells made by fixing glass rings (10 mm in diameter and 5 mm deep) to microscope slides. The depth of the substratum in the cells was about 1 mm, and the cells were closed with a second microscope slide which was kept in position with a rubber band. The culture cells were kept in a saturated atmosphere at 25°C.

For an investigation of the suitability of varions fungi as a diet for Belba 1neridionalis, culture cells 20 mm in diameter and 10 mm deep were used. Three hundred tritonymphs of this species were isolated from the Petri dish cultures. After 12 days these moulted to become adults, and after a further 4 da:ys, with the onset of spermatophore production, males and females could be differentiated. Seven adults (2 males and 5 females) were placed in each cell, and a small portion of fungus (without agar) was then introduced, each cell receiving a different species of fungus. A control cell in which agar alone was offered as food, was also set up. This experiment was replicated 4 times. These cells were kept in a saturated atmosphere at 25°C, and examined daily to assess the amount of feeding and faecal-pellet production which had occurred. Fresh fungi were supplied as needed. The numbers of eggs, larvae, nymphs and adults in each cell were noted after 104 days.

Acarologia, t. XIV, fasc. 2, 1972, rg

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The pure cultures of fungi for these studies were obtained from the Department of Soil Bio­logy, Moscow State University. Each species of fungus was grown axenically on wort agar in covered Petri dishes (roo mm in diameter, 20 mm in depth). The dishes were kept in an incu­bator at 25°C until a thick matrix of mycelia and spores had grown over the surface of the agar slants. This usually took about three weeks.

Both Petri-dish and small-cell cultures were used for observations on spermatophore produc­tion. Studies of spermatophore morphology were made with temporary mounts in glycerin, physiological salt solution and water.

TABLE I. - SPECIES STUDIED.

Species Family Locality

Palaeacarus kamenskii A. Zach. Palaeacaridae Moscow Belba rossica B-Z. Belbidae Caucasus Belba meridionalis B-Z. Belbidae Middle-Asia Metabelba rara B-Z. Belbidae Causas us Epidamaeus kamaensis Sell. Damaeidae Caucasus Epidamaeus plumosus B-Z. Damaeidae Archangelsk Epidamaeus sp. Damaeidae Archangelsk Spatiodamaeus subverticillipes B-Z. Damaeidae Cau casus Porobelba spinosa Sell. Belbodamaeidae Caucasus Oppia nova Oudms. Oppiidae Moscow Oppia concolor C. L. Koch Oppiidae Cau casus Oppia sp. Oppiidae Central-Asia Granuloppia sp. Oppiidae Caucasus Eremobelba geographica Berl. Eremobelbidae Caucasus Peloribates pilosus Mar. Hamm. Haplozetidae Caratav

RESULTS

SENGBUSCH (1954) and LUXTON (rg66) reported that mites tend to escape from shallo-vv cul­ture vessels. The results of the present study indicate that when the diet in the cultures is favou­rable, the depth of the vessel is of little consequence. For example, the failure to culture mites such as Amerus polonicus, Carabodes coriace~ts and Phthiracants sp. was attributed to an unfa­vourable diet. These mites escaped even though the culture vessels were deep. \Vith a favou­rable diet mites did not escape from cultures even when the glass cover bad slipped. In cultures of Oppia nova, mites were found on the walls of the glass cells, and in these situations fungi were also noticed.

Life-cycle Observations

Belba meridionalis and Spatiodam,ae~ts subverticillipes were successfully cultured on Peni­cillùtm martensii, and Palaeacants kamensldi, Eremobelba geographica and Granuloppia sp. on Asper gill~ts flav~ts.

Data on the !ife-cycles of these species are presented in table 2. I t will be noted that the

-283-

duration of the life-cycle of P. kamenskii is considerably longer than that of the other species, and that in the case of all species in which males are produced, the duration of the male life-cycle is shorter. A shorter male life-cycle has also been observed for five other oribatid mites, ·namely, B. rossica, Epidamaeus kamaensis, Metabelba rara, Porobelba spinosa and Oppia concolor (SHE­REEF, I970).

In the case of B. meridionalis, S. subverticillipes and Gramtloppia sp. copulation was never observed, yet all these species could produce spermatophores. Parthenogenesis was definitely established for P. kamenskii. E. geographica was not seen to produce spermatophores even though observations were carried out for more than a year. Parthenogenetic reproduction was not observed in this species.

---

Palaeacarus

TABLE 2. - Duration (in da ys) of stages in the life-cycles of five species of oribatid mites at 25°C and IOO % R.H.

(means based on 20 individuals).

Females

..<::: ..<::: r ..<::: o. o. - o. s ..<::: ,:: ..<::: o. ..<::: .... ..<:::

~ :;., o. ,:: o. +' "" o.

'" ;>-. s :;., ,:: ~ '"

;>-. s bJJ :> ç::: ;>-. " ;>-. " :;., -;;; :> ç::: ;>-. bJJ '"'

0 ç::: 0 ç::: 0 reJ ...., '"'

0 ç::: ...., ...., " '" 0

...., Species ~ '" 0 0 ., 0 -~ 0

~ f-< <Ô 0 0

>-1 ~

...., <!) ....,

'"' -~ >-1 '"' ....,

0 '9 ., ....,

~ 0

d:: <!) è ~ H <!) <!) ~ <!) 0-;

d:: '"' '"' 0-; 0-; 0-;

- - - - - ·- - -· - · - - - -

kamenskii. 2I I3 5 14 4II 5 14 4 gr - - -•••••••••••••• 0. 0. 0.

Spatiodamaeus subverticillipes. • 0 0. 0 0. 0 ••• •• II 7 4II 4 I4 414 6 75 6 3 9 Eremo bel ba geographica •• 0 0 •••• • ••• 0 •• •••• II IO 3 IO 5 IO 5 13 7 74 7 3 5 Bel ba meridionalis • 0 0 0 •• 0. 0 0 0 0 ••••••••••• 0 IO II 2 IO 2II 3 8 4 6r 9 2 5 Granuloppia sp ............................ 7 7 2 6 2 3 2 4 4 37 1 5 2 2

1 - -

Males

..<::: ..<::: o. s ..<::: o. ..0: o. s o. .±:: ;>-. s ;>-. E ., " ;>-. ç::: reJ -;;; 0 ç::: 0

;>-.

'" ...., ...., § 0 ., 0 -~ c) f-< <!)

...., '"' .-:: H

'9 ., "';' 0-; <!) , ....

<!) ~ <!)

(""' .... '"' 0-; 0-;

- - - - -- . -

1 - - -IO --;-[62 3 II 4

4 6 5 9 6 56 2 5 3 6 4 46 2 2 2 4 5 3I

-

vVhen a single male and a single female were placed together in a glass cell, eggs were laid by the females after 20 da ys in the case of S . subverticillipes, I8 da ys in the case of Granuloppia sp., and after I4 and II days in the case of E. geographica and B. meridionalis, respectively. The pre-oviposition period of P . kamenskii was found to be 9 days. The average total number of eggs produced per female was B. meridionalis, 88; E. geographica, I8 ; P. kamenskii, I7 and Gra­mtloppia sp., II.

S . subverticillipes females were seen to carry their eggs on the dorsal surface of the body (fig. I), although sometimes their eggs were deposited on the walls of the Petri dishes. The eggs of B. meridionalis andE. geographica were laid singly amongst fungal hyphae and on the exuvia of the nymphs. P. kamenskii deposited eggs on rotten wood or in crevices in the substratum.

For comparison with sorne of these observations it can be noted that PAULY (I956) reported that the duration of the life-cycles of B. clavipes and B. gracilipes was 75 da ys, and that the duration of the life-cycle of B. genicu;iosa was ISO days. He also observed that the total number of eggs laid by these mites were : B. clavipes, 6o; B. gracilipes, 70 and B. geniculosa, 40. According to SrTNIKOVA (I959), the duration of the life-cycle of Spatiodamaeus boreus is I20 da ys, while Roc-

KETT and WooDRING (r966) reported that Pergalttmna omniphagous and Ceratozetes jeweli comple­ted their lifecycles in 42 and 53 days, respectively.

In the present study the percentage survival rates in the cultures were : P. kamenskii, 95 ; B. meridionalis, 88, S. sttbverticillipes, 8o ; Granuloppia sp., 6o ; and E. geographica, 42. In comparison with the results obtained by sorne previous workers, these rates are high. For example, SENGBUSCH (r954) in studies of three species of Galumna, reported a survival rate of only 42 per cent. Again vVooDRING and CooK (r962), working with Ceratozetes cisalpimts, reported that, when reared on fungal hyphae alone, only ro per cent of the larvae survived to become adults. Moreover, the surviving adults were very short lived, and none produced eggs. Des­pite the poor survival rate reported by vVooDRING and CooK, a diet of fungi appears to be greatly favoured by at least sorne oribatids. For example, attempts to culture B. rossica and S. sttbver­ticillipes on clean hay failed, but when the mites were confined with materials such as rotten wood, moss, grass and fungi in dishes, after about two hours 95 percent of the mites were found on the fungi.

FrG. r. - Female Spatiodamaeus subverticillipes carrying the eggs on the dorsal surface.

The life span was found to vary greatly from species to species. In a saturated atmosphere at 25oC individual adults of B. 1neridionalis lived for more than a year. S. sttbverticillipes lived for about ro months, and Gramtloppia sp., P. kamenskii and E. geographica for about 7,8 and 9 months, respectively.

Feeding Experiments with Belba meridionalis

The results of the comparative study with I2 species of fungi are set out in table 3. It will be noted that the mites reproduced on all I2 fungi, but, as assessed by the numbers of individuals of all stages present in the cells aft~r 104 days, the most favourable diet was Trichoderma sp. The least favourable were Penicillium viridicatum and Mttcor ramanniamts. It is interesting

-285-

to find that a fungus most suitable for one mite species is not necessarily the most suitable for others. Thus, in earlier observations (SHEREEF, 1970) it was found that Nfucor ramannianus was the third most favourable, and Cladosporium sp. the least favourable diet for Epidamaezts kamaensis. Again, SINHA and MILLS (r968), working with ro species of Penicillium, concluded that P. cyclopium was the most, and P. impilicatztm the least favourable diet for the astigmatid mites Acarus siro and Tyrophag2ts putrescentiae.

TABLE 3· - Feeding and reproduction of Belba meridionalis on 12 species of fungi.

Di et

Trichoderma sp ... .. .. . ... .. .... .. .... ... . Penicillium martensii ......... ... .... .. .. . . Fusarium sp .... ... ... . ......... .. ....... . P. lilacinum .. ...... ................. . ... . P. spinulosum .. . . ........... ... . .... .... . . P. brevi-compactum ...................... . F. solani ... .. ........................... . Cladosporium sp .. ... .......... ..... ..... . . F. oxysporum ... ......... . .. ............. . P. viridicatum . .. ... ..... ...... ... ....... . Thfucor rarnannianus ....... . .... . ......... .

** Means from 4 replicates .

Spermatophore Production

Suitability rating

++++ +++ +++

++ ++

+ + + +

No. of ail stages in culture after 104 days**

357 2 49 175 r6o !53 123 roz 83 72 27 20

Sperm transference in the Oribatei involves the production of stalked spermatophores which are attached to a substratum and later taken up by the female . The occurrence of spermato­phores has been reported in the Belbidae by PAULY (1956), in 13 families by TABERLY (1957), in Scheloribates laevigatus and Ceratozetes cisalpimts by vVOODRING and CooK (r962)' in Perga­lumna omniphagous and Ceratozetes jeweli by ROCIŒTT and WOODRING (1956), in Hermannia p2tlchella by LUXTON (1966) and in DamaMtS q2tadrihastatus by CANCELA DA FONSECA (1969).

vVooDRING and CooK (r962) reported that the males of C. cisalpinus and 5. laevigatus started to produce spermatophores about ro days after emergence. They found that the mites deposited spermatophores on dean dry surfaces, and very few were deposited in dirty cultures containing many faecal pellets. The maximum rate of spermatophore production by one male was 20 in five hours . LIPOVSKY et al (1957) reported that spermatophores of tombiculid mites were depo­sited on the sides and on the bottom of the tubes used for breeding, and they observed that one male trombiculid produced 520 spermatophores in 24 hours.

In the present study the average number of days between the emergence of the males and the onset of spermatophore production for the various species was found to be as follows : B. meri­dionalis, E. plumos2ts and E. kamaensis, 3 ; O. concolor and JYI. rara, 4; Epidamaeus sp. and P. pilosus, 6 ; B. rossica, 7 ; Oppia sp., II ; and Gramtloppia sp., 13.

- z86 -·

The influence of females on spermatophore production varies. In the case of the r6 species observed, only S. S%bverticillipes failed to produce spermatophores in the absence of females. Males of this species kept in isolation for 9 months failed to produce a single spermatophore, but when brought into the presence of females they deposited spermatophores after 9 days.

All the species observed, except O. concolor and S. s~tbverticillipes, deposited spermatophores on the bottom and on the smooth walls of the Petri dishes and glass cells, on faecal pellets, on the food substratum and on cast nymphal skins. B. rossica even deposited spermatophores on eggs and on the dorsal surface of living mites. Spermatophores were commonly found in large aggre­gations on the glass sides of culture dishes. S. s~tbverticillipes deposited spermatophores only on the smooth walls of dishes and never on the bottom or on any other substratum. O. concolor al"o preferred to deposit spermatophores on the walls of Petri dishes and cells.

The number of spermatophores produced appears to vary considerably from species to species. Thus, when ten 'fresh' males (that is to say males which had just started to produce spermato­phores) were isolated in glass cells the number of spermatophores per male produced in one month was found to be : O. concolor, rosS; Epidantae%s sp., r49 ; E. kamaensis, r36; and P. spinosa, 74· The pattern of spermatophore production by B. meridionalis during the whole adult period is set out in table 4· It will be noted that the number of spermatophores produced decreases very sharply rz months after maturity, and that the highest number produced by a single male was 307r.

In the cultures E. phmws~ts was observed feeding on spermatophores but only fresh sper­matophores were eaten. In this connection it can be noted that RocKETT and vVooDRING (r966) observed a single incident of an adult Pergahtmna omniphagotts eating a spermatophore.

When a number of males of E. pht11tos%s, B. meridionalis, P. spinosa, Gramtloppia sp. and Oppia concolor were placed together in a Petri dish, after ro days a veritable forest of spermato­phores was produced. The large spermatophores of E. pht11WS%s and B. meridionalis were remi­niscent of high trees, while the small spermatophores of O. concolor resembled mushrooms. In this dish the females of each species unerringly picked the correct spermatophores.

TABLE 4· - Spermatophore production by Belba meridionalis.

Number of spermatophores per male

Period Lowest Highest Mean

13-28 February 1969 .......... .. .... . 86 250 r63 JVIarch ............................ . r6o 552 30I April .... . ........................ . rr8 302 r9o May .................. . .. .. .. . .... . ro8 z6o r6s June ......... . ................... . 8r zs8 I44 July ............. . .......... . ..... . 98 203 rsz August ........................... . IZO ISO IZ5 September ......... . .............. . 88 295 I73 October .............. .. ........... . 29 136 92 November ..... .. . . ............... . 135 ZI5 164 December ................. . ....... . I47 194 I78 January 1970 ........ · · · · · · · · · · · · · · III I37 I24 February ................. . ....... . 3I 93 6z JVIarch .. .................... . ..... . 9 95 52 April ........... . ................. .

Total. .. . ......................... . I5I4 307I 2205

10. Il'

A 12Vf;111

0.051fH

FIG. 2. - Spermatophore capsules of 16 species of Oribatid mites; ax. axile of spermatophore; am. ampoule cap. capsule; bul. spherical body (bulbous ?) ; s.e. sperm sac; supp. support of spermatophore; s. setules -1 - Epidamaeus plumosus ; 2 - Spatiodamaeus subverticill pes 3 - Epidamaeus sp. ; 4- Belba meri­dionalis; 5 - Epidamaeus grandjeani; 6- Hermaniella granulata; 7- Epidamaeus kamaensis; 8-Oppia concolor; 9- Granuloppia sp.; 10- Oppia sp.; II- Carabodes sp.; 12- Belba rossica 13-

Metabelba rara; 14- Porobelba spinosa; 15 - Peloribates pilosu ; 16- Diapterobates numerosus.

The NI orphology of the Spermatophores

SENGBUSCH (rg6r) and WooDRING and CooK (rg6z) observed that the spermatophore of oribatid mites consists of a slender pedicel bearing at its tip a spherical capsule containing sper­matozoa, the pedicel serving to anchor the capsule to the substratum. In the case of certain Trombiculidae, LIPOVSKY et al (1957) noted that the stalks were multiple and that the capsule rested in a fork at the top of the stalk structure. Morphological details of the spermatophore of Pergahmma omniphago%s were given by RociŒTT and WooDRING (rg66), who observed that

- z88-

the pedicel consisted of three supporting arms instead of the usual flanged single finger, and the structure of the spermatophore in Damae%s q~tadrihastat%s was described by CANCELA DA FoN­SECA (rg6g).

FIG. 3· - Spermatophores of five species of Oribatei; r - Epidamaeus plumosus; 2 - Belba meridionalis; 3- Granuloppia sp . ; 4- Peloribates pilosus; 5- Oppia concolor.

vVhile there was considerable variation in detail from species to species, the spermatophores in species belonging to the families Damaeidae, Belbidae and Belbodamaeidae, was found to be very similar in structure to that of Damae~ts q%adrihastatus (as described by CANCELA DA FoN­SECA, op. cit.). In these families, and indeed in a number of other families, the pedicel commonly terminates in an ampoule, but this ampoule was not found in P. pilos%s, Carabodes sp. nor in Diapterobates mtmeros~ts (fig. z). In Oppia sp., O. concolor, Hermaniella gramtlata, andD. mtmero­s%s, the pedicels are straight, but in the other species studied they were curved near the tip (fig. 3). In Oppia sp., O. concolor and Gran%loppia sp., the tip of the spherical capsule was seen to be covered with minute setules ( figs. 2 & 4), but in the other species investigated the tips of the cap­sules were smooth and sticky.

Previous workers have reported that the spermatozoa are contained in the spherical capsule. However, this does not always appear to be the case, for in all of the species studied in the present investigation, except Carabodes sp., the spermatozoa were found in a sac lying under the spherical capsule (fig. 5), and the spherical capsule itself contained a fluid and uniden­tified bodies. In the case of Carabodes sp., however, spermatozoa were found in the spherical sac.

-289-

Measurements of the spermatophore components in 13 species are set out in table 5· As might be expected, the length of the spermatophore pedicel is seen to be correlated with the lengths of the first and fourth legs of the male.

1

j A L..........:_ . ___ _

• • ! .\

"· ' .

\.. • ' ..

FIG 4· - Spermatophore of Granuloppia sp. Note the spherical capsule surrounded by setules .

•

0 • 1 .

FIG. 5· - Spermatophore of Epidamaeus liamaensis with and without spermatic-sac.

-290-

SUMMARY

Five species of oribatid mites were cultured on the fungi Penicillium martensii or Aspergilhts jlavus in Petri dishes and small glass cells. Data are presented on their !ife-cycles. The duration of the !ife­cycle varied considerably, and, in the case of species producing males, the duration of the male life-cycle was shorter than that of the female. Palaeacants kamenskii was seen to reproduce parthenogenetically.

Belba meridionalis was cultured in glass cells on rz different species of fungi. As assessed by the population of all stages in the cells after 104 days, the most favourable diet was Trichodenna sp., and the least favourable Penicilliwn viridicatwn and Nhtco1' ramannianus.

Data are also given on spermatophore production, and the structure of the spermatophore is des­cribed for a number of species.

TABLE 5. - Measurements of spermatophore components, spermatozoa, legs I and IV (in microns) and the numbers

of spermatozoa in the sperm sacs.

en <JJ ...., ~-.!.: ... .!.:

Q) <JJ

Cd 0 Cd ..c: ...,;:; 'H>.

,... P-< :::: ...., P-< ...., ...., 0 <JJ O';:l ...

<JJ <JJ bJJ ... P-< ... 0 Q)

..... ;:l ;:l Q) ol Q)..Cl P-< 0 <JJ 'H

~ ...., u ~r.; <JJ

'H 0 "' ~

Species ..c: 0 ..c: ~ ::: ol 'H

@ ·~ 0 ...., ...., - u bJJ ..c: -~ m.-;:l

...., :-s ·- ... i51l Q)

b.() ~ Çl Q) N Q) ~ Ui .... ;:l ..c: P-<

Q) P-< <JJ o--1 <JJ

-- -- -- - - - ---

Epidamaeus plumosus ........... 574 r6 9 z6 74 z6 2,7 x I,5 Epidamaeus sp ................. 458 !2 7 20 57 r6 J,O x r,8 Spatiodamaeus subverticillipes ... 336 27 II JO 59 23 J,O x I,5 E. grandjeani ........ . ......... 278 20 8 zr 4I r6 Belba rossica ................... 264 20 5 I4 35 7 I,5 x o,g B. meridionalis ................. I95 r6 4 II 38 II J,O x r,o E. kamaensis . .................. rgr r8 3 II 40 !2 r,g x o,g Metabelba rara .... . ............ r88 !2 4 IJ 37 9 r,8 x r,o Porobelba spinosa .............. 149 !2 3 7 27 9 2,0 x r,o Granuloppia sp ................. 83 8 I 14 r8 II IA x O,J Peloribates pilosus ............. . JO - 2 - 23 7 o,8 x 0,5 Op pia con col or ...... .. ......... 4I - 2 II 27 7 IA x o,6 Oppia sp. .. . .... . .. .. .. . ..... . 24 - 2 9 20 6 o,g x O,J

ACKNOWLEDG EMENTS

<JJ

1

E > H ... b.()

H Q)

P-< ~ bJJ <JJ ~

'H ..... 0 'H 0 0 ..c: ... ..c: Q)

...., b.() ....,

..0 ;:l bi)

8 Q) ;:l ;:l o--1 Q)

o--1 z -- ---

r8oo 832 rr64 1575 J22 932 IJOO 779 858

653 JI9 goo 55I 653 787 435 6rz 85o 421 592

II25 376 5I8 450 294 349 243 233 294 332 2!2 245 400 IJJ 250 400 204 240

The author wishes to express his deep sense of gratitude to Dr. E. M. BULANOVA-ZACHVATKINA, Department of Entomology, Faculty of Soil Science, Moscow State University, for help in identifying the mites.

Thanks are also due to Dr. T. G. MmcHINK, Department of Soil Biology, Moscow State University, who kindly provided me with the cultures of fungi.

-291-

REFERENCES CITED

CANCELA DA FoNSECA (J. P.), rg6g. - Le spermatophore de Damaeus quadrihastat2ts Markel et Mayer (Acarien Oribate).- Proc. 2nd. iut. Congr. Acarology, Sutton Bonington rg67. 227-232.

CLEAT (N.), 1953.- Growth in the laboratory of economically important oribatid mites. - Nature Lond. 169: 280.

GRANDJEAN (F.), 1950.- Observations ethologiques sur Camisia segnis et Platynothnts peltifer. -Bull. Mus. Rist. nat. Paris, 22 (2) : 224-23r.

HARTENSTEIN (R.), rg62. - Soil Oribatei r- Feeding specifity among forest soil oribatids. - Ann. ent. ent. Soc. Am. 55 : 202-205.

LIPOVSKY (L. ].), BYERS (G. W.) and KARDOS (E. N.), I957· - Spermatophores -the mode of inse­mination of chiggers . - ]. Parasit. 43 : 256-262.

LUXTON (M.), rg66. - Laboratory studies on the feeding habits of saltmarsh Acarina, with notes on their behaviour. - Acarologia, 8, r63-174.

MICHAEL (A. D.), r884.- British Oribatidae Vol. I, London. Ray Society.

PAUL Y (F.), rg56.- Zur Biologie einiger Belbiden und zur Funktion ihrer pseudo-stigmatischen Organe. - Zool. Jb. (Abt Syst.), 84 : 275-328.

RociŒTT (C. L.) and WooDRING (J. P.), rg66. - Biological investigations on a new Ceratozetes and Per­gahtmna (Acarina : Cryptostigmata). - Acarologia, 3 : 5II-520.

SENGBUSCH (H. G.), 1954- - Studies on the life history of tlu·ee oribatid mites, with observations on other species. - Ann. ent. Soc. Am. 47: 646-667.

SENGBUSCH (H. G.), rg6r.- A study of spermatophores and sperm transfer in the Oribatei (Acarina).­]. Parasit. 47 : 43-44.

SHEREEF (G. lVI.), 1970. -Observations on the feeding, reproduction and faeces obtained from oribatids fed on different species of Penicillùtm and Aspergilhts. - IVe Coll. int. de Zool. du Sol. 1970 Dijon France.

SINHA (R. N.), and lVIILLS (J. T.), 1968.- Feeding and reproduction of the grain mite and the mushroom mite on sorne species of Penicilli2tm. - J ourn. econ. Ent. 61 : 1548-1552.

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