Development, swarming, colony orphaning and fly parasitism in subterranean termites, macrotermes gilvlls (hagen) and macrotermes carbonarius (hagen) (blattodea: termitidae)
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Date
2010
Authors
Kok Boon, Neoh
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Abstract
Biological and ecological aspects of Macrotermes gilvus (Hagen) and
Macrotermes carbonarius (Hagen) namely: (1) the caste development; (2) flight
phenologies and reproductive isolation mechanisms; (3) the impact of orphaning in field
colonies; (4) fly larva parasitism in both species were focused in this study. The present
research provides insight into termite's caste developmental pathways, population
biology, colony breeding structures and community ecology.
There were three larval instars and five nymphal instars detected in the
development of minor/major workers and reproductive castes of both species. The first
larval instars consisted of both males and females that displayed homogenous sizes. Size
sexual dimorphism, in which females were smaller than males, occurred in second larval
instars, third larval instars, and worker castes. Minor and major soldiers were sterile
females. Pictorial evidence of fourth larval instar of M carbonarius is presented herein;
the individuals closely resembled those of minor workers but were poorly pigmented,
having a distended abdomen, future presoldier-like mandibles, and a meso- and
metanotum.
Chronological reproductive isolation W'lS displayed in two sympatric specIes.
Flights of M. gilvus were recorded over a remarkably long 7-month period from March
to September, while swarming of M carbonarius took place from November to January.
Swarming events of M gilvus and M carbonarius occurred under atmospheric pressures of 1,005-1,011 hPa and 1,006-1,010 hPa, respectively. Most flights of M gilvus
occurred on days with rain at dawn (0300-0430 hour), whereas M carbonarius avoided
rain at dusk (1900-1910). Flight activity of M gilvus was correlated significantly with
atmospheric pressure and rainfall. The threshold temperature and relative humidity (RH)
of M gilvus flights were between 23 and 26°C and 83 and 98% RH; M carbonarius
swarmed between 25 and 30°C and 72 and 83% RH.
Of the 38 orphaned colonies of M gilvus, 15 colonies (39.5%) re-established. In
M carbonarius, three colonies out of20 (15%) re-established. Re-established colonies
were headed by normal adultoids. In naturally-orphaned colonies of M gilvus, multiple
adultoids with normal pigmentation but tom wings were found. The number of
reproductives probably declines over time. It may take alates of M. gilvus six months to
develop to functional adultoids, and up to 12 months for alates of M. carbonarius. The
presence of sexual castes at the time of orphaning may not necessarily guarantee the
success of colonies in re-establishing themselves as breeding colonies. A high
prevalence of occupation of the mounds by other termite species was found, after the
death of M gilvus (18.4%) or M carbonarius (30.0%) colonies.
Soldiers with abnormal round head capsule and small mandibles were found in
orphaned colonies. A new fly species Misotermes mindeni Disney & Neoh (Diptera:
Phoridae), as identified infecting the soldiers of Macrotermes gilvus (Hagen). While the
Orientai Bengaliinae blow fly, Verticia fasciventris Malloch (Diptera: Calliphoridae)
was reported for the first time as an internal parasitoid of the soldiers of Macrotermes
carbonarius (Hagen). Both dipteran species demonstrated different approaches in larval
pupation while parasitized soldiers were less aggressive compared to healthy soldiers.