Optimal Temperature for Rearing the Edible Ruspolia differens (Orthoptera: Tettigoniidae)

Abstract

Ruspolia differens Serville (Orthoptera: Tettigoniidae) is an insect with significant economic potential in Africa. However, to mass-rear this species on a large scale, the optimal rearing temperature needs to be determined. We assessed multiple performance traits for R. differens reared at seven constant temperatures, ranging from 18 to 32°C, from newly hatched nymphs to 3 wk after adult molting. The highest observed survival was at 30°C (mean survival of 86.7%), where also the development rate reached its maximum. At this temperature, the development from newly hatched nymphs to adults took approximately 49 d. The weight of individuals at the time of adult molt reached its maximum at 28°C (mean weight of 0.62 g). To maximize the yield from mass-rearing, suggested time to harvest R. differens is 10 d after the adult molt. According to our results, during this time period R. differens individuals can achieve up to 50% higher weight than if harvested immediately after adult molting. For maximal survival and weight gain, we recommend rearing temperature of 28-30°C, whereas a slightly higher temperature of 31°C leads to the shortest development time. Taking into account all the performance traits, the overall optimal temperature is estimated at 29°C. Our results can be used when developing large-scale, mass-rearing protocols for R. differens in controlled temperatures.

Fatty acid content and composition in edible Ruspolia differens feeding on mixtures of natural food plants

“…Therefore, it is likely that the fatty acids (or their precursors) were insufficient to build a heavy fat body with the grass inflorescence diets studied. Compared to our previous studies [ 19 , 20 ], feeding on artificial diets generally produced R. differens with relatively higher weight (0.4–0.65 g) than with natural plant diets studied here (0.41–0.45 g), which could be related to a higher fat content of artificial diets than in grass inflorescences.…”

Growth performance and feed conversion of Ruspolia differens on plant‐based by‐product diets

“…In addition, the fatty acid composition of R. differens can be manipulated with its diet (Lehtovaara et al, 2017; Rutaro et al, 2018a,b), i.e., with specific feeds, it can become even more suitable for human consumption. Recently, there have been attempts to develop mass‐rearing methods for this species (Lehtovaara et al, 2017, 2018; Malinga et al, 2018a,b; Rutaro et al, 2018a,b), which could prevent overharvesting of the wild populations in the long‐term. Ruspolia differens has potential for mass‐rearing in the Lake‐Victoria basin, where there are long traditions for consuming this species, but also elsewhere, as the species is nutritionally valuable due to its healthy fatty acids.…”

The edible katydid Ruspolia differens is a selective feeder on the inflorescences and leaves of grass species

“…The overall acceptance scores of both leaves and inflorescence were lower for females compared to males in no‐choice experiments. Both sexes of R. differens accumulate weight as adults, but females generally gain more weight than males (Lehtovaara et al, in press) and thus should have an overall higher demand for food. Previous studies have found sex‐specific host preference or selection (Boys, ; Behmer & Joern, ; Franzke et al., ) and higher food consumption levels by females compared to male orthopterans (Delvi & Pandian, ; Unsicker et al., ).…”