Water‐relations of the termites Macrotermes bellicosus (Smeathman) and Trinervitermes geminatus (Wasmann)

Abstract

Workers of Macrotermes bellicosus and Trinervitermes geminatus lost water quickly by total transpiration, in dry air at 34° C. The former died in less than 300 minutes while the latter died in 450 minutes. However, workers in groups of five and ten showed greater resistance than solitary individuals. When tested in dry air at different temperatures, solitary workers of both species died at about 41° C while insects in groups of five or ten died at 43° C and 45° C respectively. M. bellicosus survived after losing up to 50 % of its initial weight while T. geminatus died after losing about 60 % of its initial weight. After desiccation in dry air at 36° C for two hours the workers of both species gradually lost weight when tested in decreasing relative humidities. It was shown in M. bellicosus that the uptake of O2 was much higher in solitary workers than in groups. Temperature and relative humidity within groups of workers of both species in dry air at 34° C were not significantly different from those of the surroundings. Zusammenfassung Über den Wasserhaushalt der Termiten Macrotermes bellicosus und Trinervitermes geminates Arbeiter von M. bellicosus und T. geminatus verlorcn bei trockener Luft und 34 C schnell ihr Körperwasser durch totale Transpiration. Die ersteren starben in weniger als 300 Minuten, die letzteren in 450 Minuten. Dabei zeigten Arbeiter in Gruppen zu 5 oder 10 eine größere Resistenz als einzelne Individuen. Bei trockener Luft und verschiedenen Temperaturen starben einzelne Arbeiter beider Arten bei ungefähr 41° C, zusammen zu 4 oder 5 erst bei 43° C bzw. 45° C. M. bellicosus verlor dabei bis zu 50 %, T. geminatus etwa 60 % des Ausgangsgewichtes. Nach 2stündiger Austrocknung in trockener Luft bei 36° C verloren die Arbeiter beider Arten mit abnehmender Luftfeuchtigkeit zunehmend an Gewicht. Es zeigte sich, daß die Sauerstoffaufnahme von M. bellicosus bei einzellebenden Arbeitern wesentlich höher war als bei Gruppen. Die Temperatur‐ und Luftfeuchtigkeitswerte innerhalb von Gruppen von Arbeitern beider Arten in trockener Luft und 34° C waren nicht von jener der Umgebung verschieden.

Survival of Termites (Isoptera) Exposed to Various Levels of Relative Humidity (RH) and Water Availability, and Their RH Preferences

“…This aggregative huddling was likely a behavioral mechanism to prevent desiccation from water loss through evaporation from the body by decreasing overall surface area of the group. This behavior, termed the "group effect" by Grasse and Chauvin (1944), was reported to increase termite survival for several species (Pence 1956;Sen-Sarma & Chatterjee 1966;Minnick et al 1973;Abushama 1974;Ahmad et al 1982;Malik & Sheikh 1990;Cabrera & Rust 1996).…”

Abiotic and biotic determinants of West African termite mounds in altered land

“…The particular abundance of small mounds ( Trinervitermes and Cubitermes genus) may be due to their preference for the ecological conditions on bowé . These species are more tolerant of dry air (Abushama, 1974) and can increase four to fivefold over 2 years in fire‐protected plots (Benzie, 1986). In addition, Trinervitermes genus likes grass availability of food, high relative moisture, low air temperatures, social life and clay soil availability (Ohiagu & Wood, 1976; Sands, 1961, 1965).…”

“…The particular abundance of small mounds (Trinervitermes and Cubitermes genus) may be due to their preference for the ecological conditions on bowé. These species are more tolerant of dry air (Abushama, 1974) and can increase four to fivefold over 2 years in fire-protected plots (Benzie, 1986). In addition,…”

The role of internal and external constructive processes in evolution

“…These termites commonly inhabit environments with strong seasonal variation in environmental moisture: wet summers with torrential rainfalls alternating with very dry winters (Turner, ). During the winter, termites mine water from perched water tables below the surface and transport it to the nest, carried either in the abdomen as imbibed water, or in dollops of wet soil (West, ; Abushama, ; Sieber & Kokwaro, ; Lys & Leuthold, ). During the wet summers, termites transport excess water from the nest into the mound in the form of wet soil.…”