Cannibalism among adult bush crickets (Ruspolia differens) when fed on different insect preys and artificial diets

Abstract

Edible bush cricketsRuspolia differens have received considerable interest in recent years primarily due to their widespread consumption across Sub Sahara Africa. Currently, these pseudo grasshoppers are only available in large quantities twice a year during the rainy seasons. Therefore, there is great research interest in studying their farming potential for possible mass rearing. However, due to their cannibalistic behaviours, such attempts have proven an uphill task. This study evaluated measures that may reduce cannibalism by providing alternative prey to rearedR. differens. Ten young adults of either females or malesR. differens were kept separately in well-aerated cages (50×50×50 cm). Then, two sets of experiment were set up as follows: in the no-choice set-up, twenty live or dead second instar (L2) larvae each ofHermetia illucens,Chilo partellus,Bactrocera invadens, andSchistocerca gregaria were administered separately to both male and female cages for six successive days. In the choice set-up, a mixture of twenty live or dead L2 larvae of the insects mentioned above was fed for twelve consecutive days. The control diets included an artificial diet only or artificial diet + corn leaves and were provided for six days consecutively to both males and females separately. In each case, the proportion of cannibalism and the possibility of hunting behaviour byR. differens was recorded. Cannibalism was significantly reduced in both male and femaleR. differens cages where prey was administered compared to the control diets. Besides, cannibalism was significantly reduced in both male and femaleR. differens cages when live insect prey was provided compared to dead insect prey. There were indications of a hunting behaviour exhibited byR. differens as they tended to feed more on living than on dead insect prey. Our findings show that the addition of live insect prey could reduce the prevalence of cannibalism duringR. differens, thus preventing colony collapse due to cannibalism and also providing a safe means to eliminate insect pests, which could serve as prey.