A TECHNIQUE FOR ESTIMATING HATCHING OF NATURAL EGG POPULATIONS OFMELANOPLUS SANGUINIPES(ORTHOPTERA: ACRIDIDAE)

Abstract

The earliness or lateness of the hatching period in Melanoplus sanguinipes (Fabr.) affects the type and amount of damage to the crop and the timing of control measures. An empirical model for prediction of hatching at each decile of egg populations was developed by multiple regression using daily maximum air temperatures for a unit interval of 5 days from 2 March to 29 June and embryonic development in the preceding fall. The model accounted for a maximum of 96% of the variance in hatching date. It showed the average effect of a unit change of 1° of daily maximum temperature for each of the 24 5-day intervals on the number of days to hatch. The time and pattern of hatching of the major bulk of egg population was dependent mainly on spring temperature; however, fall embryonic development accounted for considerable variation in hatching time especially of the less developed eggs. The implications for population growth and certain assumptions made during the analyses in this study are discussed.