Journal of Chemical Ecology (1999) 25, 1029-1042

Abdoulaye Niassy, Baldwyn Torto, Peter G.N. Njagi, Ahmed Hassanali, Daniel Obeng-Ofori and Jonathan N. Ayertey (1999)
Intra- and interspecific aggregation responses of Locusta migratoria migratorioides and Schistocerca gregaria and a comparison of their pheromone emissions
Journal of Chemical Ecology 25 (5), 1029-1042
Abstract: Gregarious nymphs of Schistocerca gregaria and Locusta migratoria migratorioides are often seen to march together in common bands in the field. In the present study, the intraspecific aggregation responses of nymphal and older stages of the two insects were compared with their interspecific responses. Unlike S. gregaria, L. m. migratorioides shows a lesser pattern of stage and sex differentiation in its aggregation pheromone biology. Thus, although fifth-instar nymphs did not respond significantly to the adult pheromone, adults responded significantly to the nymph pheromone. No cross-stage aggregative responses occur in S. gregaria. In the adults of S. gregaria, production of the pheromone is male-specific; in L. m. migratorioides both sexes induced a significant level of aggregation from conspecifics. Aggregation assays between corresponding stages of the two species showed stronger interaction between the nymphal stages than between the adults and account for the frequent occurrence of mixed hopper bands in the field. GC-EAD studies of volatiles of nymphal and adult stages by using antennal preparations from both species also showed significant interspecies reactivities. GC-MS analyses showed that of S. gregaria nymphal pheromone components (C₆ and C₈ to C₁₀ straight-chained aldehydes and acids and the fecal phenols, guaiacol and phenol), the acids and phenols constitute the common components of nymphal stages. Phenylacetonitrile, the major component of S. gregaria adult aggregation pheromone, is present in L. m. migratorioides nymphal volatiles, albeit at a lower level. Unlike S. gregaria adult pheromone blend, which is made up wholly of benzene derivatives, the volatile emissions of L. m. migratorioides adults is dominated by aliphatic aldehydes and alcohols. The possible role of cross-aggregation effects in mutually facilitating phase transformation of the two species is discussed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Jonathan N. Ayertey, Baldwyn Torto, Ahmed Hassanali, Daniel Obeng-Ofori, Abdoulaye Niassy, Peter G.N. Njagi

Research topic(s) for pests/diseases/weeds:
pheromones/attractants/traps
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Schistocerca gregaria
	Locusta migratoria