Acrididae
Taxonomic placing: Hemimetabola, Orthoptera, Acridoidea.
Common name: Short-horned grasshoppers.
A family of short-horned grasshoppers with a short ovipositor. The tympanum is located on the first abdominal tergum, which is fused with the metathorax. The tarsus is three-segmented.
This family includes species designated as locusts on the basis of morphological and behavioral characteristics. Locusts differ from other acridoid grasshopper species in the degree to which they display polymorphism and phase-related behavior. The term “phase” is used here in its broad sense as encompassing a continuous polymorphism with “solitariform” referring to the extreme manifestation of isolated-type morphometrics and cryptic coloration, while “gregariform“ denotes contrasting color patterns and characteristic morphometrics dominant in crowded populations. Gregarious phase is reinforced by the persistence of density and duration of isolation or aggregation. This applies not only to the life history of the individual locust but to the continuity below or above a certain density over several generations. It follows that locust phase is not an “all or none” phenomenon. Morphology, coloration and behavior are expressed to varying degrees depending on the density and duration of gregarization. In fact, to complicate matters, there are some indications that behavioral characteristics of acridid grasshoppers not normally considered locusts are density dependent. The line of demarcation between “simply a grasshopper” and “definitely a locust” is not that clear.
After attaining reproductive competence, terminal oocytes develop synchronously in panoistic ovaries. The gravid female of most species deposits egg-pods in the soil on bare ground or close to roots of vegetation, probing the soil with her ovipositor to chose appropriate soil composition, moisture, pH and salinity The size and shape of egg-pods are characteristic for each species.
Different locust species migrate to different extent, while non-migratory strains of typical locust species, or strains with reduced migratory capacity or absence of gregarious coloration, have been noted in isolated locations. This illustrates the potential for plastic response which may occasionally lead to population outbreaks of minor grasshopper species, inflicting chronic annual damage to crops which may exceed the damage caused in peripheral locust invasion zones by occasional swarms.
Three acridid locusts species, belonging to three subfamilies, are presently of variable agricultural importance in the Middle East: The Desert Locust (Schistocerca gregaria) (Cyrtacanthacridinae), which has the potential to cause considerable damage, The Migratory Locust (Locusta migratoria) (Oedipodinae) which has established local populations and is of minor importance and The Moroccan Locust (Dociostaurus maroccanus), which may occasionally cause damage.
References
Centre for Overseas Pest Research (COPR) 1982. The Locust and Grasshopper Agricultural Manual. London.
Fishelson, L. 1985. Orthoptera: Acridoidea. Fauna Palaestina - Insecta III. The Israel Academy of Sciences and Humanities, Jerusalem.
Uvarov, VB. 1966. Grasshoppers and Locusts, Vol. 1, Cambridge: Cambridge University Press.
Uvarov, VB. 1977. Grasshoppers and Locusts, Vol. 2, London: Centre for Overseas Pest Research.
Websites:
Association for Applied Acridology International.