Food consumption of the cockroach species Blaptica dubia Serville (Blattodea: Blaberidae) using three leaf litter types in a microcosm design

Abstract

This study investigated the effect of different plant litter types and developmental stages of the cockroach species Blaptica dubia on food consumption, animal growth, and excrement production. Three leaf litter species Alnus glutinosa, Acer platanoides, and Quercus robur were selected as model plants in a microcosm test in which plant litter was consumed by three different cockroach instar groups during five consecutive one-week intervals. At each interval, litter consumption, animal weight, and produced excrements were measured. The results showed slightly higher consumption of A. glutinosa compared to other leaf litter species in all three age/size groups of animals. Animals gained weight with time, especially Group B (medium-sized class animals) feeding on Alnus. The production of excrements was higher in Group C (big class animals) and increased in Alnus among litter species. Foliar litter consumption and excrement production rates were highest in B and C animal groups and in Alnus treatments; however, animal growth rates did not show a clear pattern, except for A. glutinosa. Measured energy contents showed highest values for animals, but slightly higher for leaves compared to excrements. Our results show that using energy budget parameters can help explain the relationship between litter type, cockroach sizes, and their consumption in this microcosm experiment.