Bulletin biologique de la France et de la Belgique (1960) 94, 203-263
Marguerite Papillon (1960)
Étude préliminaire de la répercussion du groupement des parents sur les larves nouveau-nées de Schistocerca gregaria Forsk
Bulletin biologique de la France et de la Belgique 94, 203-263
Abstract: As recently revealed by investigations of the progeny of Red and Migratory locusts, both birth-weights and the number of ovarioles are influenced by differences of phase status inherited by the mother and grand-mother; an inverse relationship is maintained between these two characters, such that the heavier larvae have fewer ovarioles, and conversely. The subject is here furthered by a series of preliminary observations on Desert locust hatchlings, but a full interpretation of the results will be published at a later stage, when, it is hoped, more evidence will have been acquired.
As in the case of Locusta and Nomadacris, crowding Schistocerca females reduces the number of oothecae laid and also the number of eggs per ootheca. However, marked distinctions are to be noted between the species when the effects of parental grouping are investigated in the progeny. For both the Red and Migratory locusts, the light hatchlings exhibiting a high number of ovarioles and the heavy larvae with fewer ovarioles are normally produced, respectively, by solitaria and gregaria mothers. But in the case of the Desert locust, the full range of birth-weights and ovariole numbers can be produced by the same ootheca, the proportion of one or the other type of hatchling being determined by the phase status of the mother parent. The isolation of females will lead to the production of a majority of green larvae with low birth weights and a high number of ovarioles, and a minority (approximately 12%) of black or intermediate colour forms with fewer ovarioles and higher birth-weights.
Conversely, crowded mothers will yield a preponderance of black hatchlings and roughly 16% of larvae of the opposite type. Thus in Schistocerca, more so even than in Nomadacris, relict forms exhibiting opposite characteristics to those pertaining to the mother are included in each ovarial cycle.
A further distinction is that afforded, in both gregaria and solitaria pods, by the triple relationship between time of hatching, location of eggs in the ootheca and the colour of the hatchlings they produce. Thus, at 30° C., the minority green forms in gregaria pods tend to hatch approximately 20 hours later than the black larvae. Even within the same colour category, the lighter larvae take longer to hatch; also, observations on the progeny of solitaria females indicate that the number of ovarioles is greater in those which have a longer period of incubation.
Finally, studies so far pursued only on gregaria pods have revealed the occurrence of a gradient in the ootheca, such that the heavy black larvae with a reduced number of ovarioles are mainly produced by the upper and median thirds of the pod, whereas most of the green minority types hatch from the lower third.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: French)
Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
Pest and/or beneficial records:
| Beneficial | Pest/Disease/Weed | Crop/Product | Country | Quarant.
|
|---|---|---|---|---|
| Schistocerca gregaria |
