Predicting the current and future distribution of the edible long-horned grasshopper Ruspolia differens (Serville) using temperature-dependent phenology models. (January 2021)

• Record Type: Journal Article
• Authors: Leonard, Alfonce; Egonyu, James P.; Tanga, Chrysantus M.; Kyamanywa, Samuel; Tonnang, Henri Z.E.; Azrag, Abdelmutalab G.A.; Khamis, Fathiya M.; Ekesi, Sunday; Subramanian, Sevgan
• Is Part Of: Journal of thermal biology. Volume 95(2021)
• Publication Date: 2021-01
• Subjects: Life cycle modelling -- Development rate -- Mortality -- Fecundity -- Lifetable parameters -- Climate suitability; Thermobiology -- Periodicals; Temperature -- Periodicals; Biology -- Periodicals; Thermobiologie -- Périodiques; Thermobiology; Periodicals; 571.46
• DOI: 10.1016/j.jtherbio.2020.102786
• Languages: English
• ISSNs: 0306-4565

Abstract

Abstract: The edible long-horned grasshopper Ruspolia differens (Serville) is widely distributed and consumed in sub-Saharan Africa. Efficient mass rearing of the edible grasshopper is critical to ensure their sustainable supply for food and nutritional security. Hence, we investigated the effect of temperature on development, survival and reproduction of R. differens under six constant (15, 20, 25, 30, 32 and 35 °C) and fluctuating temperatures. Using Insect Life Cycle Modeling software we fitted, linear and non-linear models to R. differens development, mortality, longevity, and fecundity. The best-fitted functions were compiled for each life stage to yield a phenology model, which was stochastically simulated to estimate the life table parameters. We used the process-based climatic phenology models, and applied establishment risk index (ERI) and generation index (GI) in a geographic information system to map the potential distribution of R. differens under current and future climates. At optimum temperatures of 30–32 °C, egg incubation period was 14–15 days and the developmental time was shortest at 52.5–58 days. Lowest nymphal mortality (3.4–13%) and the highest female fecundity was obtained at 25–30 °C. The optimum temperature for the reproduction ranged between 27 and 30 °C. Most simulated lifetable parameters were at their maximum at 28 °C. Predictive models showed that countries in the East, Central, West, Southern and the Horn of Africa were suitable for establishment of R. differens under current climate scenarios (2000). However, by 2050, climatically suitable areas for the establishment of R. differens were predicted to shrink in the West, Southern and the Horn of Africa than its current distribution. We predict up to three generations per year for R. differens in sub-Saharan Africa under current scenarios which can increase to 4 under future scenarios. The optimum rearing temperatures identified can guide optimization of mass rearing of R. differens. Highlights: Life table parameters predict 27° C to 30° C as optimum temperatures for rearing edible grasshoppers, Ruspolia differens. The generation time at optimum rearing temperatures (28° C to 30° C) ranges from 67.3 to 78.6 days. The lowest mortality rate was at 25° C to 30° C and eggs were more resistant to extreme temperatures. The Central, East, West and southern Africa is suitable for establishment of R. differens with 3 generations per year. In future, the suitability for R. differens will be restricted to Central and East Africa with 4 generations per year.