The Collophore

The collophore is the tube-like structure on the ventral side of the first abdominal segment of the body of springtails - it's what gives this group their name. Interestingly enough, although there are springtails without springs, as far as I'm aware there are no springtails without a collophore.

The collophore is used for in osmoregulation - water intake and excretion. In addition, the tip of the collophore carries mechano- and chemoreceptors which allow the animal to sense its environment. The collophore is actually a tubular pouch usually terminating in a bilobed vesicle, hence when fully extended the tip is forked (it is derived from a modified pair of abdominal appendages). At rest the collophore is contained within the body of the springtail but by contracting muscles and exerting hydrostatic pressure on the vesicle the springtail can evert the tube in order to drink. The collophore also works in opposition to the furcula (the spring) and can be used to control the direction in which the animal jumps (Favret, C., Tzaud, M., Erbe, E.F., Bauchan, G.R., & Ochoa, R. (2015) An Adhesive Collophore May Help Direct the Springtail Jump. Annals of the Entomological Society of America, 108(5), 814-819). In at least some globular springtails the long prehensile vesicles are coated with an adhesive substance that permits the springtail to right itself when on its back.

14.07.18 - Let The Hard Times Roll

Recording at Herbert's Meadow, I also attempted to look for springtails. Unlike a few days previously, I wasn't able to start sampling until after 9am. Everything was bone dry so I concentrated on sweeping vegetation in the shade. After half an hour I'd only found two springtails, one Entomobrya nicoleti and one Entomobrya nivalis:



These tough arboreal species are clearly the last to go in dry conditions. However, the Ulverscroft brook still had an inch or so of water flowing, so on the way back I also sampled from vegetation along the banks, and from liverworts and mosses on stones in the stream. Small beetles and spiders were abundant, and I thought I'd found a few globbies, but on closer examination, they all turned out to be tiny spiders or mites. This cannot be due to humidity which was locally high (the mosses were damp), so must be related to temperature.

So where are all the springtails? In aestivation as dormant (diapause) eggs in which embryonic development is delayed until moisture increases and temperatures fall. It will be interesting to see how quickly populations recover when this 50 year drought ends.

"Species of Collembola adapted to periodic drought have been found in Australian and Mediterranean ecosystems, as well as in the Antarctic where desiccation occurs due to the extreme cold. Some of these desiccation-resistant species are encountered in temperate European arable ®elds, in particular Lepidocyrtus spp., Pseudosinella spp., Isotomurus palustris, I. viridis, I. notabilis, Sminthurus aureus and S. viridis. Our study found evidence for the existence of desiccation-resistant stages only in S. viridis amongst this list of Collembola. Other species which have previously been found aestivating did not hatch out under our experimental set-up, despite being common in the yields from which the samples were taken (e.g. Lepidocyrtus spp., I. palustris, I. viridis, I. notabilis). Previous studies in Europe have found that the populations of some Collembola were not detrimentally affected by dry periods (e.g. Entomobrya nivallis)."
Alvarez, T., Frampton, G.K., & Goulson, D. (1999) The effects of drought upon epigeal Collembola from arable soils. Agricultural and Forest Entomology, 1(4), 243-248.

12.07.18 - The Drought Continues

The East Midlands in now in the worst drought for several decades. Not surprisingly, springtails are thin on the ground (which is absolutely bone dry). Part of our local churchyard is managed to encourage wildlife, so I turned out at 6am before it warmed up. There was no dew - all the vegetation was completely dry - but sweeping long grasses (choosing the few remaining green patches) yielded a lot of Entomobrya intermedia:


There was also a single Entomobrya nicoleti:




Deuterosminthurus pallipes was also abundant:



Not a big haul but good considering the drought.

06.07.18 - Launde Big Wood

On a short trip to Launde Big Wood recording butterflies I also sampled springtails, which have never been recorded here before. The conditions were hot and very dry (no dew in the morning) so I only sampled by sweeping vegetation.

Deuterosminthurus pallipes was the most abundant species:



Entomobrya nivalis was also quite frequent:



There were a small number of Lepidocyrtus lignorum:





I also found one Dicyrtomina minuta:




More dots on the map for Leicestershire springtails.

Lepidocyrtus

General characteristics:
Adb4 more twice as long as abd3; most species have blue pigmentation but this is only clearly visible in natural light and easily lost in alcohol-preserved specimens. Presence or absence of scales on legs and antennae are an important character in this group but these can be very difficult to see (especially confirming their absence) so exercise caution. 

Pale species; Th2 not prominent:

• Lepidocyrtus lanuginosus: predominantly pale with traces of blue pigment on the head, thorax and legs; no scales on the legs or antennae; interocular macrosetae present.
• Lepidocyrtus lignorum: predominantly pale with faint traces of blue pigment on the head, thorax and legs; scales present on the legs and ant1+ant2, no scales on ant3+ant4 (c.f. L. curvicollis); eyepatch roundish (less elongate than other species); no interocular macrosetae:

Lepidocyrtus lignorum: angle between head and body relatively straight, >=90 degrees, scales on the 2 basal antennal segments and legs, no scales on ant3 and ant4, eyepatch roundish (less elongate than other species):









Blue/violet pigmented species; Th2 prominent to varying degrees:

• Lepidocyrtus curvicollis: a pale species with traces of pigment on the head, thorax and legs; Th2 overhangs the head dorsally - head tucked under thorax; scales are present on the legs, and on ant1-4 (like L. paradoxus).
• Lepidocyrtus cyaneus: blue pigment on the head, thorax, abdomen and legs (less obvious in artificial light), no scales on legs or antennae. Note that the blue pigment of L. cyaneus can only be seen in descaled specimens as the blue is not an iridisation colour of the scales but an intrinsic colour of the naked (descaled) skin. Interocular macrosetae present.
• Lepidocyrtus violaceus: strong blue pigment on the head, thorax, abdomen and legs; scales on the legs and ant1+ant2, no scales on ant3+ant4; no interocular macrosetae.
• Lepidocyrtus paradoxus (absent from UK?): dark body, pale legs; Th2 very prominent, angle between head and body <90 degrees and scales on the 2 basal antennal segments and legs.

Lepidocyrtus cyaneus: blue pigment on the head, thorax, abdomen and legs (less obvious in artificial light), no scales on legs or antennae. Note that the blue pigment of L. cyaneus can only be seen in descaled specimens as the blue is not an iridisation colour of the scales but an intrinsic colour of the naked (descaled) skin. Interocular macrosetae present:





Lepidocyrtus violaceus: strong blue pigment on the head, thorax, abdomen and legs, scales on the legs and on the first (ant1) and second (ant2) segments of the antennae, but NOT on ant3 and ant4:







Lepidocyrtus paradoxus: angle between head and body < 90 degrees, scales on the 2 basal antennal segments and legs. Photo by Marie Huskens:

17.06.18 - Billa Barra

Although it had been very dry for the past month I was hopeful that rain over the previous 24 hours would mean more springtails. In the event, sampling from wet vegetation proved to be quite tricky. I didn't not find any springtails on Gorse, which was still quite dry, but there were lots on the grass. In the field, I thought I had found Sminthurus viridis but on closer examination, these proved to be aphids! Only one species was present, Deuterosminthurus pallipes (form repandus) - this is by far the predominant arboreal species at present, seemingly undeterred by warm dry weather.





Ocelli [3 (B C H) - 1 (D) - 4(A E F G)]: