All taxa of Orthoptera known from the latest Eocene deposits of the Isle of Wight are redescribed or discussed, based on the study of their type material. The following new taxa are described: Ontogryllus gen. nov., O. rossi sp. nov. (type species), Achetomorpha gen. nov., A. irregularis sp. nov. (type species), and Proeneopterotrypus gen. nov. The latter genus is here proposed for Pteroplistes danicus Rust, described from the Palaeocene/Eocene of Denmark, as this find is important for understanding the systematic position of the genus Eneopterotrypus Zeuner. Remarks about the taxonomy of the taxa studied, age of these deposits, and ecology are given.

Blaesoxipha atlanis (Aldrich) is a common parasitic fly of agriculturally important grasshoppers in Canada. The suitability of Camnula pellucida (Scudder), Melanoplus bivittatus (Say), Melanoplus packardii Scudder, and Melanoplus sanguinipes (Fabricius) as hosts was studied in the laboratory. Grasshoppers were singly-parasitized or left unparasitized and reared for 9 days. Melanoplus bivittatus and M. packardii did not support parasite development, i.e. were non-permissive hosts. In both species, parasite larvae were melanized and encapsulated, but development proceeded further in M. packardii. Melanoplus sanguinipes and C. pellucida were permissive host species with, respectively, 70% and 35% of the implanted larvae emerging from their hosts of which 86% and 50% developed into adults. Parasite development time was longer in C. pellucida. Adult B. atlanis dry mass varied with host species and host mass at parasitism, but not with host sex. Parasites developing in M. sanguinipes were larger in terms of dry mass than counterparts developing in C. pellucida. In permissive species, unparasitized grasshoppers gained in body mass while parasitized insects lost mass during the 9-day observation period. In non-permissive species, all insects gained in body mass, but parasitized females gained less mass than unparasitized conspecifics. All unparasitized grasshoppers survived while 75–95% of permissive and 30–40% of non-permissive hosts died. Variation in the intensity of field parasitism among grasshopper species may be explained, at least in part, by qualitative differences in suitability between potential host species. Novel pest management strategies emphasize preservation of a small proportion of the pest population for natural enemies. Consideration of the outcome of specific host-parasite interactions should improve the understanding of grasshopper population dynamics and increase the predictive value of models that assess potential crop losses.

Little is known about phase polymorphism in the red locust, Nomadacris septemfasciata (Serville) in Madagascar, despite its economic importance. Only solitary and transiens forms have been reported from the island earlier, but not the gregarious form. Important recent outbreaks have allowed for the studying of the phase polymorphism under experimental and field conditions. Morphometric differences (pronotum size and shape, and F/C and E/F ratios) were noted among hoppers and adults caged for several generations and at various densities, in a field laboratory. These criteria were later used to study adults collected in different areas between 1996 and 2002, from populations with various densities (<1000 to >25,000 imagos/ha). Morphometric measurements revealed that gregarious red locust populations have existed naturally in Madagascar and that these were erroneously classified as transiens forms. The upper threshold density for the solitary phase was estimated at 5000 adults/ha; beyond this limit, locusts develop either into transiens or into highly gregarious forms. The southern part of the island, known as a red locust outbreak area, has harboured gregarious phases despite previous reports that prevailing ecological conditions are not suitable for its complete phase transformation. Deforestation in the northern part of the island has probably led to new favourable biotopes for serious outbreaks and gregarious populations development.

The historical account of the rise and fall of Nosema locustae as a biological control agent of grasshoppers has substantial implications for the successful development and implementation of biological control of migratory locusts in Africa. The potential of N. locustae was ultimately not sufficient to overcome a set of impediments, including: efficacy (the rate and extent of mortality were relatively low), target specificity (not all pest species were susceptible), formulation (wheat bran bait excluded feeding by some pests), cost (the price of the formulated product was excessive), storage (the organism lacked long-term stability), complex application (the pathogen and its carrier had to be applied during a narrow set of environmental and logistical parameters) and production (the use of an in vivo production system made high-volume production difficult). Some of the most significant limitations that led to the failure of N. locustae have been overcome by work on other pathogens, including the problems of formulation, storage, efficacy and production. However, at least four relevant lessons can be derived from the N. locustae story and applied to ongoing work with biological control of migratory locusts. First, the erratic population dynamics of acridids necessitates that the production, storage and distribution of an augmentative biological control agent will be driven by a boom-and-bust cycle. Second, the immense spatial scale and low unit value of the resources (rangelands) being protected create a unique set of logistical challenges. Third, the control of acridids involves the management of a native insect pest embedded within complex, native ecosystems, which suggests that our interventions should be undertaken with a great deal of caution, monitoring and, ultimately, humility. Fourth, although pathogens can be used as ‘bio-insecticides’, biological control requires education of end-users regarding a more sophisticated approach to pest management.

Consumption indices and apparent digestibility are measured for seven species of grasshoppers from Lamto (Ivory Coast), representative of different trophic specialization steps (Le Gall and Gillon, 1989), The consumption indices vary from 0.11 to 0.34 and the apparent digestibility from 30 to 65%. Specialists are not more efficient on their host plant than are generalists on convenient host plants, but some specialists fed on plants which are not convenient for generalists. Anthermus granosus and Eucoptacra spathulacauda feeding on Lippia multiflora is not convenient for a generalist like Eucoptera anguliflava. If feeding efficiency does not seem to be a real selective pressure, it can be an important step in specialization processes, when there is an adaptation to an unusable host plant for polyphagous species.

Differences in the constitution of plant parts eaten by the grasshopper play an important role in the digestibility. The differences in the efficiency observed between the two specialists of Lippia are from their differences in feeding behaviour.