Acid phosphatase activity in hemolymph of the migratory grasshopper,Melanoplus sanguinipes, duringBeauveria bassiana infection

The distribution and abundance of acid phosphatase (AP) in hemolymph (HL), plasma (PM) and hemocyte lysate supernatant (HLS) of the migratory grasshopper,Melanoplus sanguinipes infected withBeauveria bassiana (strain GK 2016) has been examined. AP activity was determined at intervals from 30 min to 60 h postinjection of 2 μl of 1×10⁸ conidia/ml per grasshopper. The enzyme was detected with the substrate β-glycerophosphate in sodium acetate acetic acid buffer form hemocytes (HC) and withp-nitrophenol phosphate sodium salt for HL, PM and HLS. In results of experiment 1 proportion of HC showing AP activity increased 1–2 h, then returned to normal after 4 h. However, inB. bassiana-injected grasshoppers, a second increase was noted 24 h later which was not seen in the Tween-80-injected insects. Uninjected controls showed no change with time in the proportion of HC with AP activity. Studies were also made of the distribution of AP activity in the HL, PM, and HLS. AP activity in HL appeared to vary with the sex of the grasshoppers. Females showed increase in AP activity in HL 18–24 h after injection withB. bassiana, whereas males only showed an increase 1 h after injection. Assay of HLS showed that the level of AP activity did not change significantly throughout the experiment. Changes in AP activity in PM, in bothB. bassiana — and Tween-80-injected insects (both sexes) paralleled those of the HL, indicating that the enzyme is released from the HC. The observations are discussed in terms of the possible role of AP in the immune response ofM. sanguinipes.