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Wednesday, August 25, 2010

Damp Wood Termites Of Malaysia.

From just a few bad characters and the hypes of pest control companies,  sensational news and science reporting, termites generally gets a bad rap. Most termites species inhabiting tropical rainforest cannot survive outside of this habitat as they need both the diverse vegetation for food and the humidity level for their above ground foraging (including their covered corridors).

Most wood eating termites feed on dead wood with only a few termite species feed on living trees, or the cellulose composed parts of living part of trees.

That is not all, many species also do not feed directly on wood but dead wood and plant matter in various stage of decomposition. These are humus (aka soil) feeding species such as Dicuspiditermes, Pericapritermes, Procapritermes and many others in this classification group; Labritermes,

There are also the lichen and moss feeding species such as Longipiditermes and Hospitalitermes. These also feed on seeds and fruits.

Then of course there are damp wood termites. which feeds on decomposing wood with high moisture content that are on the forest floor.

As their labeling suggest damp wood termites feed only on dead wood that has a high moisture content (damped with moisture). This makes them a friendly termite that will not cause damages to humans habitations and other constructions made of wood, unless of course your habitations and structures are of damp wood, dead wood soak with moisture are naturally soften wood and will crumple and break much more easily than wood that are not damp.

Unlike dry wood termites which are serious pest of furniture and wooden structures, damp wood termites are generally not regarded as pest (except by pest control companies and scientists because then they can make money from you either directly or indirectly) as their diet consist primarily of rotting and damp tree branches and trunks on the forest floor.

Prorhinotermes flavus (includes all species of this genus and possibly also other dampwood termite genera) are the easiest of termites to rear. Generally wood eating (as opposed to soil eating and fungus growing) termites are relatively easy to rear but dampwood termites take the prize as being the easiest to rear.  

Image 1: Prorhinotermes flavus soldiers and alate (i.e. reproductives)

The species shown in this page is Prorhinotermes flavus. The Prorhinotermes genus consists of some twenty described species with 'most' found in South East Asia and a few found in the New World namely Florida and the Caribbean. Prorhinotermes flavus is the only species documented as found in my location.

This species (as maybe also generally be true of dampwood termites) is quite unique or atypical among termites in many ways. It may well be the only (or one of very few, at least I have not encountered any other and this species describe here in this post) termites species where the males attack one another in a fight for females. Many (but not all) termites once the founding pair has established the beginning of a colony, the pair will fiercely attack any other reproductives that encroached into their nest.

It may also be the only termites where the alates are aggressive and will bite sometimes for no apparent reasons. I have a few landed on me and just bit me for no apparent reason. But that is not all, the bite is venomous and left a small swelling or welt that itches for a while (into the next day). Not venomous as in snake venomous but as in ants or bee sting venomous. This would make Prorhinotermes flavus the first and/or the only documented (or described, here in 2020 03 26)  termites species that has a venomous bite. I haven't read of any other termites species where the alates has a bite that is venomous.

Image 2: The swelling or welt left by the bite
from a Prorhinotermes flavus alate. It did not let go for a while so I killed  it with my fingers by pulling on its body and it got separated from its head which was still stuck to my hand. The pain was similar in intensity as the sting from Tetramorium ants (not as intense or painful as Solenopsis geminata). Please note that ants (include bees, wasp and hornets) do not have a venomous bite, it is their sting (or for those stingless, the venom secreted from the opening at the end of their abdomen or gaster) that is venomous.

There are also a few other behavior traits that set Prorhinotermes flavus apart from most other termites. These are: the pair alates if one of the pair died during the incubation period the other will dig itself out from the nest to seek out another of the opposite sex.

The nymphs began to be active and participate in the nest care and foraging from after the second molt (during the second instar growth stage). The number of molt or instar stage of Prorhinotermes flavus also appears to be not fixed but varies according to the growth rate, in faster growing cases there are fewer instar stages and in slower growth cases (especially during the colony founding) there are more instar stages 

If the founding pair die and there are no mature or imago (those that past their last molt) workers or soldiers, then the nymphs (or larvae) from after the second/third instar onwards (if there are a couple to a few of different sexes), a pair or more (depending on how many workers there are at the time the primary reproductives died) will 'metamorphosed' (transform themselves without molting) into (secondary reproductives). These are nymphal (secondary) reproductives.

The soldiers and workers of Prorhinotermes flavus are monomorphic though different sizes workers and soldiers may seemingly be found in a colony, they are non imago or not mature individuals who will still molt. The appearance of different sizes of workers (as opposed to nymphs or larvae) are actually nymphs (from the context of not yet reaching their final stage of development and they will still molt). In Prorhinotermes flavus (and also other species of this genus) the immature (or nymphal) workers can suspend their growth to remain at the 'adolescence (non imago) stage' and a specific instar stage for long period (months to over a year or two) as the founding colony very slowly grows.

As far as termite goes, the growth rate of the colony of Prorhinotermes flavus is extremely slow. No doubt the quality of food (i.e. cellulose based matter) plays a big part but even factoring this, from eggs to hatching alone is one and a half times longer than the typical termites (of this location).

The development from eggs to imago (whether workers, soldiers or reproductives) have more molts (i.e. instar stages) than the typical termites, but not only that the number of molts are not fixed with more nymphal stages (aka instar stages) in founding colony than in mature colonies. Eggs take some one and a half to two months to hatch (most termites eggs, from this location, hatch in around a month). Workers (including nymphs) and soldiers can transform into secondary reproductives.


A similarity of damp wood termites with dry wood termites is their small numbers. Each nest rarely consist of more than a few hundred individuals. Kept nest can reach considerable much larger numbers though.

Images 3 & 4: Damp wood termites used their droppings together with chewed wood fragments to seal their tunnels' openings. The droppings aka fecal pellets of damp wood termites are almost identical to dry wood termites except that they are not dry but moisture laden. And similar to drywood termites they also excrete a sticky substance (part of their excrement) which glue their dry fecal pallets together to block their tunnels' opening.
This very soft material obviously do not serve well as a protection against their predators such as ants and other predatory arthropods. That is the reason the ratio of soldiers to workers are higher than in typical termites species. Additionally the soldiers secrete a liquid that repels ants causing them to frantically rub themselves to rid themselves of the repellent.

Image 5: Nymphs of damp wood and dry wood termites are the most mobile of all termites nymphs. Workers nymphs of damp wood termites (except for the newly hatched) are fully functional members of the nest, the worker nymphs foraging for food and feeding the newly hatched nymphs, soldiers, other workers and the reproductives. Reproductive alates, soldiers and workers of Prorhinotermes flavus all measured around five millimeters. They are among a few species where the exoskeleton of the head are fully hardened in the nymphal stage after the second molt into the the third instar. The imago (or fully developed) workers have a darker head coloration. Image below shows five instar stages of worker nymphs.
Image 6: Prorhinotermes workers are according to authoritative sources, not true workers but are pseudergates (the reasons they are called pseudergates is according to scientific logic because they are not true workers or true gates but can't be called pseudogates or pseudoworkers because it will offend their sensitivity and they might sue for discrimination) which will in the course of growth developed into reproductives. On thing they failed to mention is that even the soldiers can 'transform' into (secondary) reproductives.

Image 7: This would (naturally) means that even the soldiers of Prorhinotermes flavus are not true soldiers but are also pseudergates (image above, a secondary queen from the soldier caste).
Prorhinotermes termites have one of the fastest transformation rate (less than a month) from workers/soldiers (and even the nymphs in the third instar onwards can transform) into secondary reproductives while those of fungus growing species have the slowest (four months or more) with the replacement reproductives (whether king or queen, or both) developing through all the stages into winged reproductives from second or third instar nymphs or larvae.
Image 8: full fledge (or 'imago') workers of Prorhinotermes flavus.

Image 9:  Soldiers of Prorhinotermes flavus, these are still one instar smaller than 'full fledged' soldiers. But Prorhinotermes seemingly make the meaning 'full fledged' as unclear there are four stages in the soldier development when the cuticles or exoskeletons have 'hardened' that these soldiers already take on the role of defenders.

Image 10: A soldier of Prorhinotermes flavus

Image 11: A soldier of Prorhinotermes flavus

Image 12: Some workers (in various stages of growth) and a final stage soldier of damp wood termites.

Images 13: Various sizes of workers of damp wood termites.

Images 14: The full fledged aka final worker has a darker head capsule coloration.



  Image 15: Damp wood termites workers and last instar (pre-adult) nymph.

Image 16: Closeup of a damp wood termite worker.

Image 17: A group of damp wood termites workers, nymphs and soldier.

Image 18: A group of damp wood termites workers, nymphs and soldier.

Image 19: Some workers of damp wood termites and a nymph in its last instar.

Image 20: A worker of damp wood termite and a maturing nymph.

  Image 21: Close up of two soldiers of a species of an Asian damp wood termites.

Image 22: A soldier of Prorhinotermes flavus

Image 23: Close up of a soldier of Asian damp wood termite.

Image 24: The reproductive nymph with her rudimentary wings.

Pocket Pet. Fancy a colony of termites you can carry with you in your shirt pocket. This colony is around eight months old. Colony growth in Prorhinotermes flavus is extremely slow.

Image 25: Workers and soldiers of Prorhinotermes flavus.

Image 26: Newly hatched nymph (i.e. larva) of Prorhinotermes flavus. Unique (this is the only case from this location that I have encountered among termites nymphs) among termites nymphs, the newly hatched nymph of Prorhinotermes flavus has an upward pointing abdomen.

Image 27: This is probably because of its tiny size and damp living environment makes this a necessity as these tiny newly hatched nymphs will get stuck to the cohesiveness of water droplets and drown.

Image 28: Nymphs, soldiers and a worker of Prorhinotremes flavus. A secondary reproductive (from a soldier) on the right side of photo, partially hidden by a worker and a nymph (aka larva).
 Generally, in true dampwood termites both adult soldiers and workers commonly 'metamorphose' (without molting) into male and female reproductives.

Image 29: A clutch of eggs of a Prorhinotermes flavus colony, soldiers and nymphs

Image 30: Prorhinotermes flavus nymph molting on its own. Most termites cannot successfully molt on their own but this species is one of the very few which can.

Image 31: A newly paired (after a nuptial swarm) reproductive of Prorhinotermes flavus. Reproductives of Prorhinotermes flavus are slightly smaller than the workers.

Image 32: A battle scarred male reproductives of Prorhinotermes flavus with one missing leg and one shortened antenna. Males (reproductives) of Prorhinotermes flavus are aggressive against other males and will attack one another biting off antennae and legs in fights over females during nuptial pairing.

Image 33: A pair of Prorhinotermes flavus primary reproductives (center female, center left - male) and a pair of secondary (or neotenic) reproductives (right center - male, and top - female) with workers and larvae aka nymph.

A founding colony (below) with some twenty numbers of individual loses both the founding reproductives and several still non fully developed workers at third instar (fully developed workers are fourth instar), metamorphized into four secondary reproductives. These reproductives are notably smaller (around 1 mm smaller than the typical fully developed workers at around 5 mm) than the regular such reproductives of matured colony.

Image 34: Three nanitic soldiers, several nanitic (3rd instar workers) and four nanitic secondary reproductives of Prorhinotermes flavus of a one year old growing colony with some twenty individuals (inclusive of nymphs or larvae) and eggs, which had lost its original founding pair (king and queen) some months ago. Strictly speaking these are not nanitic as they are intermediary (and will continue their growth, molt several times until they reach the full size as soldiers or workers) stages still. They are essentially still in larval or nymphal transition and have yet to complete all their instar molts.

Image 35: Here (top photo) is the comparison between a normal imago queen and (bottom photo) the (four) larval or nymphal secondary reproductives of a (around) one year old colony. These neotenic (secondary) reproductives developed or metamorphosed from workers just in their second instar (or third stage) nymphal or larval workers.

A baby (non imago worker aka nymphal) secondary reproductive
of Prorhinotermes. (click on video then click play to view)

Image 36: These 'premature' or nymphal (as opposed to the normal neotenic) secondary reproductives (left in image above) are much lighter in coloration than normal secondary neotenic reproductives which are the same dark coloration as primary reproductives. Note the size of the normal reproductive (a queen) is much larger than the "nanitic" nymphic (not that they are but they just haven't reached their final molt size yet) secondary reproductives (which metamorphized from nanitic workers). These are about the same size as the nymphal workers. In Image 33 (above) are some normal workers which metamorphized into neotenic secondary queens. These are the same size as normal imago queens.

Image 37: Three different instar (nymphal or larvae) secondary neotenic reproductives of Prorhinotermes flavus. In these two photos (image 37 above and 38 below) we see there are three different sizes of Prorhinotermes neotenic reproductives each from a different instar (3rd, 4th and 5th) nymph or larva. Image 37 LHS second smallest, center smallest and slightly bottom (just above the nymph and worker) largest. 
Image 38: bottom largest (beside the imago worker bottom left), center second smallest (just below the nymph) and top center smallest (above the primary reproductive). Including worker (full fledge or imago stage) caste and soldier secondary reproductives there are a total of five caste of secondary reproductives in Prorhinotermes flavus not counting the main or primary reproductives.

Image 40: Neotenic (secondary) queen from a nymph (i.e. larva). This neotenic queen 'transitioned' directly from a nymph or larva without molting. Note the head of the neotenic queen is smaller than the fully developed worker (carrying an egg in its mandibles).

Image 41: Secondary queens of Prorhinotermes flavus. In ants there are species that are polygynous, in termites Prorhinotermes is the closest thing to polygyny in termites. The colony (shown above) has around thirty five workers, around ten soldiers and seven secondary queens and one secondary king, plus one nymph transitioning (or transforming) to a secondary reproductive. One of the queen is a soldier queen (center of photo above, see also video below). All the workers are still larvae (or nymphs) and have not complete their growth yet. And all the soldiers are nanitic not full size soldiers. Even the soldier queen transform from a nanitic soldier. Note the soldier queen is smaller than the worker queen (i.e. which transformed from a full fledged or fully developed worker).

In this video (above) you can see the soldier queen (top center) the one with a shortened (broken) right antenna trying to hide instead of standing guard. (click on video then click play, to view)

Here is a cut section showing the soldier queen (the one with the right antennae broken) which developed or metamorphed from a nanitic soldier (note that the soldier queen is significantly smaller than the worker queen)
(click on video then click play, to view)

Image 42: A 'soldier gate or soldier pseudergate' aka soldier neotenic secondary queen (i.e. a soldier queen). Of course 'soldier gate' are not just secondary queens but can also be kings. Though these are less common than those that transition from workers as the soldier caste of most termites comprises of females (especially the major soldier caste lesser so the minor soldier caste). I hesitate to use the term 'neotenic' here because when is a soldier termite an under developed baby?

Image 45: secondary queen from a soldier (bottom center)
Secondary queens from soldiers are not common but do sometimes happen in Prorhinotermes flavus (and also typically other genus of dampwood termites) that a soldier would transform herself to become a queen. And even rarer are secondary kings from soldiers. Generally with termites with dimorphic workers and soldiers caste, the major morphological expression commonly developed from females, while with those having monomorphic workers and soldiers, the females commonly developed into soldiers and males into workers.

I do not have the facilities to examine why a larva stage nymph or even a soldier will transition into a secondary reproductives but I suspect it lies with the individual termite which first senses the absence of a reproductive caste in the colony. I have colonies with mature workers and nymphs and the nymphs transition (but not developed because no growth or molting is involved) into neotenic (i.e. secondary reproductives) but not the mature workers. Though typically (as is more common) it is the mature (i.e. full fledged or fully developed) workers that would take on the role when a colony lacks (i.e. loses a reproductive or got separated from the main colony).

Image 43: Worker instars

This is the first and only termite I have encountered where swarming males are aggressive against each other. A possible reason (just a conjecture) could be due to the small numbers released (in nuptial swarms) so there becomes a crucial need for males to fight off other males whenever they located or are following a female. In most termites the alates (both male and female) are around the same size, while in some species the female are noticeably larger. But in Prorhinotermes flavus, it is the reverse, the males more often are noticeably larger than the females. This is probably due to males needing to fight off other males.

This is the most atypical termite species I have encountered. If two workers (from third instar) are separated from the colony and reared separately, the two workers (condition upon one being male and the other female) will begin the transformation into secondary reproductives without molting.


Evolution Is By Opportunities And Needs Not By Accidents

All damp wood termites irrespective of the genera tend to exhibit quite similar phenotype such as their workers and soldiers can and do become secondary reproductives. The nymphs too exhibit similar morphological characteristics.

Workers and soldiers are typically very long lived, as long lived as or almost as long lived as the primarily queens and kings.

These are driven by the temporarily nature of their habitat where damped wood seldom last for years and years and the termites are of necessity quite the nomad moving from one decomposing moisture laden nest to another. A colony of these types are often separated leading to the workers and soldiers developing into secondary reproductives quite quickly. A small batch of workers and soldiers separated from the colony will quite quickly become a viable colony of its own.


See also:


Taxonomy:
No rank: Opisthokonta
Kingdom: Metazoa
No rank: Eumetazoa
No rank (Subkingdom): Bilateria
No rank (Branch): Protostomia
No rank (Infrakingdom): Ecdysozoa
No rank (Superphylum): Panarthropoda
Phylum: Arthropoda
No rank (Subphylum): Mandibulata
No rank: Pancrustacea
Subphylum (Epiclass): Hexapoda
Class: Insecta
No rank (Subclass): Dicondylia
Subclass (Infraclass): Pterygota
Infraclass: Neoptera
No rank (Superorder): Dictyoptera
Order: Blattodea
Superfamily: Blattoidea
Suborder: Isoptera (this Suborder/Infra family/No rank is no longer included aka rejected, by most to nearly all taxonomy authorities, I am a stubborn hold out but what do I know)
No rank: Termitiodea
Family: Rhinotermitidae
Subfamily: Prorhinoterminae
Genus: Prorhinotermes
Species: flavus


Updated: 2022 06 25
First Posted: 2010 08 25
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