The effects of diet on quantitative nutritional indices were measured in fifth-instar female nymphs of the grasshopper, Euprepocnemis plorans. Analysis of the main and interactive effects of feeding on the host plants lupine (Lupinus termis), horsebean (Vicia faba) or clover (Trifolium alexandrinum) and some of the plants' allelochemicals indicated that nymph performance was adversely affected by the hydrogen cyanide (HCN) and quinolizidine in horsebean and lupine respectively. Assimilation of clover was higher than of lupine or horsebean. Relative growth rate (RGR) was significantly higher in grasshoppers fed on clover than in those fed on either lupine or horsebean. Relative consumption rate (RCR) was in the order lupine > clover > horsebean. The efficiency of the digested and ingested food conversion were significantly lower in grasshoppers fed on lupine or horsebean than those fed on clover. The duration of the fifth instar was in the order horsebean > lupine > clover. Grasshoppers fed on horsebean or lupine lost weight during the experiment, with a greater weight loss recorded in those fed on horsebean. Grasshoppers contained the highest concentration of haemolymph proteins when fed on clover. Short-term feeding on lupine and horsebean resulted in 10 and 20 % mortality respectively, and nymphs that died on a horsebean diet were malformed.

Effects of adult nutrition were investigated by measuring female longevity, body weight, fertility and ovariol yield in the grasshopper, Euprepocnemis plorans reared on 3 different host plants. Rearing the insect on lupine (Lupinus termis) and horsebean (Vicia faba) caused significant reduction in fertility and ovariol yield of its first and second pods compared with those reared on clover (Trifolium alexandrinum). Resorption bodies were significantly higher in the ovariols of females fed on L. termis and V.faba. Diet also affected longevity and body weight. Fecundity was highest in females reared on T. alexandrinum. Significant reduction in haemolymph protein was noted in females reared on L. termis and V. faba. Nitrile (allylcyanide) significantly reduced the approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD), inhibited nymphal growth, increased food consumption and decreased its assimilation. Feeding grasshoppers on T. alexandrinum treated with 125–250 μ mole/g resulted in various degrees of malformation and death.