A comparison of the mechanisms controlling the hatching time and synchrony of the desert locust Schistocerca gregaria and the Bombay locust Nomadacris succincta (Orthoptera: Acrididae)

Hatching behaviors of the desert locust Schistocerca gregaria (Forskal) (Orthoptera: Acrididae) and the Bombay locust Nomadacris succincta (Johannson 1763) (Orthoptera: Acrididae) were observed to analyze the mechanisms controlling the hatching time and synchrony. At a 12-h thermoperiod of 25 °C and 30 °C under continuous illumination, most eggs hatched during the low temperature period in the desert locust, and the proportion of such individuals was lower in eggs kept in a mass than in those kept singly. In the Bombay locust, most eggs hatched during the high temperature period; however, the inter-pod variation was large. Both locusts hatched earlier with increasing the egg mass size in a range from 2 to 10 or 20 with similar hatching intervals. Desert locust eggs from different pods advanced the hatching but did not delay it to synchronize the hatching. In contrast, Bombay locust eggs advanced or delayed hatching depending on the age of the paired egg. The results suggested the presence of embryo–embryo interactions. In both locusts, a vibrational stimulus that was emitted by the embryo and transmitted via a piece of wire was likely to be responsible for synchronized hatching. The hatching patters of these species were compared with those reported previously for other taxa.