Biological studies on the ‘senene’ longhorn grasshopper, ruspolia differens serville (orthoptera: tettigoniidae), in northwest Tanzania

The biology of Ruspolia differens, the longhorn grasshopper widely known as senene by its Kiswahili name, was largely unclear although this insect serves broadly as a delicacy relish snack. In this study, the biology of senene from Northwest Tanzania was inferred based on the swarming, morphological and molecular characters, with which its taxonomic status was delineated. Sampling of the species was done in 4 months of swarms and the closest other 4 months of non-swarming phase. Analysis of swarming involved the origin and plasticity of swarms based on the occurrences of the adults, nymphs and eggs, upon which the life cycle of this insect was, for the first time, explicated. Morphological analysis was done based on colour polymorphism and external anatomy whereas the molecular study involved phylogenetic relationship of this species based on the nuclear ribosomal 18S sequences. It was found that the phenology of swarming of senene is highly predictable and taxonomically useful due to its uniqueness. The species also has an exceptional colour polymorphism that is characterized by 6 morphs whose relative frequencies vary interactively with sex ratio and seasonal environmental conditions. Tegminal black speckles are useful genetic biomarkers for the browns and there are unique anatomic features that can serve largely in diagnosis of this species and these include the paired male metathoracic flaps, finger-like prosternal protuberances, hind femoral spines, sub-equal tibial markings and an obvious male biased antennal dimorphism. The closest species to this insect is Ruspolia nitidula and the closest genera to the genus Ruspolia include Conocephalus and Platycleis. The biogeographical profiles have inferred that the genus Ruspolia and relatives originated in the African Tropics.