Temperature related effects on embryonic development of the Mediterranean locust, Dociostaurus maroccanus

Laboratory studies were conducted to assess the effect of temperature on th e development of the eggs of Dociostaurus maroccanus (Thunberg) (Orthoptera , Acrididae) during anatrepsis (stages I-XIV) and during catatrepsis (stage s XV-XX). The developmental rates of anatrepsis were studied at five consta nt temperatures ranging from 10 to 30 degrees C. Egg development occurred o ver the entire range but at 10 degrees C the embryos were unable to complet e anatrepsis. The relationship between temperature and developmental times for completing anatrepsis was analysed by the non-linear Logan type III mod el. The optimal temperature estimated for the development of eggs during an atrepsis was 24.7 degrees C; the lower and upper thermal thresholds were 9 degrees C and 31 degrees C, respectively. Once the embryos completed anatre psis, only those incubated at 15 degrees C continued morphogenesis beyond s tage XIV (diapause stage) without a low-temperature exposure period. The de velopmental rate of catatrepsis was studied at four constant temperatures r anging from 15 degrees C to 30 degrees C after exposure to low-temperature, 10 degrees C, for 30, 60 or 90 days. For catatrepsis, temperature and deve lopmental time were linearly and inversely related. Linear regression was u sed to estimate the lower developmental threshold and the degree days requi rements for catatrepsis. Both decreased with longer exposure to the low tem perature; the former from 13.8 degrees C to 10.5 degrees C and the latter f rom 212.8 to 171.5 degree days, following 30 and 90 days at 10 degrees C, r espectively. Our results improve the ability of decision support systems fo r Mediterranean locust pest management by providing better forecasts to lan d managers and pest advisors.