Consumption Rate of Lichens by Constrictotermes cyphergaster (Isoptera): Effects of C, N, and P Contents and Ratios

Abstract

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.