The consumption of lichens by Constrictotermes cyphergaster termites is suggested in the literature, but not yet with concrete evidence. We examined the use and richness of lichens consumed by C. cyphergaster during both the dry and rainy seasons in a semiarid environment in northeastern Brazil by monitoring the foraging of five termite colonies for ten consecutive days during each period. Twenty-nine species of corticolous lichens were consumed by C. cyphergaster, with seasonal variations in the richness of their ingestion. Chrysothrix xanthine, Pertusaria flavens, and Dirinaria confluens were the lichen species most consumed. TLC analyzes of termite gut contents revealed twelve secondary lichen compounds ingested in both seasons, while staining showed fragments of fungal hyphae, green algae, and typical lichen spores. This study represents the first systematic survey of the abundances of lichens that compose the diet of C. cyphergaster and indicates the seasonal selectivity of that resource related to the chemical compositions of the lichen stalks.

Wood is the main dietary item for most termites; however, supplementation with certain nutrients may occur via the ingestion of other available food resources in the ecosystem. The objective of this study was to evaluate the consumption of lichens with different C, N, and P contents by Constrictotermes cyphergaster under laboratory conditions, and estimate the intake of this substrate by this species in a semi-arid area of Northeast Brazil. The foraging activities of fifteen field colonies were monitored over 15 days from 6:00 p.m. to 6:00 a.m., and the lichens that were consumed were identified. Blocks of lichen thallus (1.5 × 1.5 cm) of four lichen species were offered to the termites in the laboratory. The mean total consumption rate of lichen by C. cyphergaster was 0.032 mg lichen/g termite (fresh weight)/day. Dirinaria confluens was the lichen most consumed by termites (0.010 mg lichen/g of termite (fresh weight)/day), followed by Lecanora spp. and Haematomma persoonii at a mean consumption of 0.008 and 0.006 mg lichen/g termite (fresh weight)/day, respectively. Based on the size of the C. cyphergaster populations, the estimated lichen consumption rate was 105.12 g lichen/ha/year. Lichen consumption was significantly affected by the N content and the C:N and C:P ratios, with the N content being the factor that best explained the consumption by the termites. The results suggest that C. cyphergaster can use lichens as a supplemental source of nutrients, especially nutrients that are found in low concentrations in wood.

The present study was undertaken at Fazenda Almas Private Natural Heritage Reserve (RPPN) (07° 28’S; 36° 52’ W), located in an area of Caatinga (thorny, deciduous, dryland) vegetation in Paraíba State, northeastern Brazil. The RPPN occupies an area of approximately 3.505 ha. The region has a mean total annual precipitation of 560 ± 230 mm; and mean annual temperature and humidity of 25.8 °C and 65% respectively (^{Núcleo de Meteorologia Aplicada, 1987}).

Termites are among the insects that consume lichens and may be potential dispersers of these symbionts. This study evaluated the vitality of photobionts and mycobionts after passing through the digestive tract of Constrictotermes cyphergaster. The percentage of live and dead algae was verified throughout the alimentary canal of 450 workers, originating from five sampled colonies in the Caatinga Dry Forest, NE, Brazil. A progressive growth in algae mortality was observed in the crop, paunch and rectum, however more than 40% of the algae found in faeces presented signs of vitality. Photobiont morphology was different between cells extracted from thallus in natura and algae present in termite faeces. The photobiont cells presented more shrunken cytoplasms after passing through the alimentary canal of C. cyphergaster. There was also an increase between the cell wall space and the cytoplasm membrane of algae found in the termite faecal pellets. Only four broken spores were found in the intestine, which made the vitality analysis unfeasible for these cells. The record of photobiont vitality in termite faecal pellets is indicative of endozoochoric dispersal, suggesting that this relationship between insects and lichens extends beyond a trophic interaction.