This research expands upon our previous molecular phylogenetic analysis of the genus Melanoplus by incorporating additional mitochondrial genes, taxa and specimens. Included are two monotypic genera suspected of close affiliation with Melanoplus: Phoetaliotes and Bohemanella. Portions of four mitochondrial genes, coding for cytochrome b, cytochrome oxidase subunits I and II, and NADH dehydrogenase subunit II, were sequenced and phylogenetically analyzed using (weighted and unweighted) parsimony and neighbor-joining methods. Maximum resolution of relationships was achieved using weighted parsimony and by treating all sequences, totaling 1716 base pairs, as a unit.

The following large clades emerged in parsimony analyses, supported by moderate to poor bootstrap values: A — sanguinipes, femurrubrum, devastator, gaspesiensis, fasciatus, borealis, madeleineae, dawsoni; B — packardii, foedus, angustipennis, gladstoni, aspasmus; C — bivittatus, franciscanus, keeleri, calidus, littoralis, differentialis; D — infantilis, alpinus, aridus, Phoetaliotes, scudderi; and E — confusus, Bohemanella, marginatus, microtatus. M. lakinus was basal to all species. Deviations from the conventional literature in which species are organized into species groups or series are discussed. It is concluded that many such groups are phylogenetically questionable; their validity warrants serious reconsideration.

Two phenomena - a rapid burst (or bursts) of speciation occurring early in the genus' evolution and an absence of complete lineage sorting for certain closely related species - are nicely illustrated by Melanoplus. We provide evidence that the massive radiation that took place within the past 4 My, inferred previously by Knowles and Otte, extends to a wider base of taxa, beyond the particular species studied by these authors.

The Moroccan Locust Dociostaurus maroccanus is a pest species, regularly harmful to pastures and agricultural output in numerous circum-Mediterranean regions and particularly in Morocco. Species belonging to the same subfamily (Gomphocerinae) are mostly grass-feeding and oligophagous; very few are monophagous or polyphagous. Instars and adults of D. maroccanus are characterized by a high degree of polyphagy. Linked to this diet is mandible type; chemoreceptor organs (antenna and palp sensilla) are related to odor or taste (e.g., labrum sensilla). As labrum sensilla plates are correlated with labrum width, we eliminated this source of bias with linear regression statistics. We first studied the genesis of type A sensilla through the different stages of D. maroccanus. The relative numbers of A10 increase in adults. Then we tested if the variation of sensilla number relates to the systematic position of the genus or to diet. Comparisons concerned the relative numbers of different sensilla categories in 10 species of acridians. In all its sensilla types, the genus Dociostaurus is closer to the mostly polyphagous Oedipodinae than the mostly oligophagous Gomphocerinae. Thus diversification of diet in the genus Dociostaurus is linked to an increase in the number of labrum sensilla.

We measured hemolymph Na and K concentrations, gut Na and K concentrations, transepithelial electrical potentials (TEPs) and fluxes of Na , K and water for the insectivorous praying mantis Tenodora sinensis (Orthoptera: Mantidae). In addition, we calculated transepithelial potential differences for Na (E_Na) and K (E_K). In the mantid, Na concentrations were higher in the hemolymph than in the crop, caeca, midgut, ileum, and rectum. Potassium ion concentrations were lower in the hemolymph than in the crop and rectum. All mantid TEPs were lumen negative. The crop TEP was less negative than the TEPs for the anterior and posterior caeca, anterior midgut, posterior midgut, and ileum. Mantid E_Na values were all negative and E_K values were all positive. Mantid caecal Na , K and water fluxes were all relatively small. These data imply that digestion of insect prey occurs largely in the crop, and the caeca and midgut may not play important roles in digestion. To maintain ionic homeostasis, mantids may actively transport Na while passively distributing K . We discuss these data for mantids in comparison to previous data on the gut function of desert locusts.

Lactista eustatia n. sp. is described from St. Eustatius, West Indies. This is the first record of the genus in the West Indies.

It has been hypothesized that some herbivores may increase the cycling of nutrients in ecosystems, thereby increasing plant production even after herbivore consumption is considered. Such herbivory could maintain the productivity of ecosystems and should not be curtailed. This contrasts with the traditional view whereby herbivory always reduces plant production. Two grasshoppers (Melanoplus sanguinipes and Ageneotettix deorum), considered pest species in Western US rangelands, are experimentally shown to enhance plant production under certain conditions and to diminish it under others. Plant production increased when grasshoppers' consumption increased nitrogen cycling, nitrogen being the limiting resource for plants at the study sites. This happened when grasshoppers consumed plant species with slowly decomposing litter, favoring plants whose litter decomposed rapidly, such that their store of nitrogen was more rapidly released to the soil. However, feeding preferences change between sites and with grasshopper species, creating a spatial mosaic in which grasshoppers can increase and decrease plant production. Because changes in plant species composition are the major reason for changes in nutrient cycling rate, plant communities are created that will persistently exhibit enhanced or diminished production. Therefore, grasshoppers cannot be generally viewed as detrimental to rangeland productivity and grasshopper control may need to be more judiciously applied.

The Wisconsin Department of Natural Resources has identified a new State Natural Area in the Lower Chippewa River region of western Wisconsin. This 100,000-ha area contains 800 ha of prairie remnants—25% of Wisconsin's remaining remnant prairie. Diversity of grasshopper populations (Orthoptera: Acrididae) was assessed in these remnant prairies. Remnants ranged in size from <1 ha to > 60 ha, and contained from 6 to 15 species from four subfamilies. Half of the remnants contained 10 or more species. Data from this survey provides the Wisconsin Department of Natural Resources with a tool to evaluate remnant prairies, and a snapshot of what grasshopper communities may have looked like in Wisconsin prior to settlement. This research also updates the Orthopteran literature database for acridid distribution records for this region of the USA.

The insect growth regulator diflubenzuron (Dimilin®) is used to control locusts and grasshoppers on rangeland and croplands worldwide. Ingestion of diflubenzuron by immature insects results in disruption of chitin formation and deposition that affects the cuticle and the molting process. Symptoms of diflubenzuron intoxication include: death, physical abnormalities (such as loss of limbs), lethargy and cessation of feeding. Field trials with diflubenzuron on grasslands are reported in this paper and support previously published work showing it to be effective in broadcast treatments or alternating swaths and barriers. Affected insects were observed 3 d after application but maximum control of populations occurred by 14 d. Low grasshopper population counts the year after application suggested fewer eggs hatched from adults exposed to diflubenzuron. This bears out results of earlier laboratory and small-scale experiments. Diflubenzuron applications to rangeland did not seriously affect the populations of nontarget arthropods.

Population dynamics of an acridid grasshopper, Diabolocatantops pinguis, were monitored for 3 y, from October 1990 to September 1993, at two sites in Tamil Nadu, a southern state of India. The fluctuations in the population at the two sites were related to abiotic factors, such as maximum and minimum temperatures, rainfall and relative humidity, using Kendall's correlation coefficient test. We tested a hypothesis that the effects of each abiotic factor may be varying, i.e., from immediate to delayed. These analyses involved several correlation coefficient tests. Hence we also performed a sequential Bonferroni test to eliminate levels of significance that emerged due to sheer chance. Maximum temperature imposed a significant delayed negative effect on the population of this species that was prolonged 2–3 mo. Minimum temperature had a significant negative lag effect of about 2 mo. at Tambaram. Rainfall had a significant positive effect on the population immediately at Tambaram or with a lag (∼ 1 mo.) at Chinglepet. Relative humidity had a significant positive lag effect of about a month at Chinglepet only. The trends in the immediate effects of abiotic factors on the population of D. pinguis in both the study sites were comparable.

A new species of Phlugidia (Orthoptera: Tettigoniidae: Meconematinae) is described from the East Usambara Mts, Tanzania; a list is given of Saltatoria species occurring in the same habitat.

Two new species of Acrometopae and the female of Lamecosoma inermis Ragge are described from Tanzania, East Africa. Horatosphaga parensis n. sp. occurs in montane forest clearings of the South and North Pare Mountains. Peronura uguenoensis n. sp. inhabits herbaceous vegetation in the North Pare Mts. Notes on altitudinal distribution and habitat requirements are given for both species. L. inermis is an inhabitant of the savannah grasslands in the colline and submontane zone of southeast and eastern Kilimanjaro.

A project to develop a biological control strategy for locusts and grasshoppers is being conducted in Mexico. Major activities include: surveys of entomopathogenic fungi, laboratory screening of isolates, testing of methods for mass production, and formulation and field evaluation of virulent strains.

The Centro Nacional de Referencia de Control Biológico (CNRCB) has, in its entomopathogen collection, 40 isolates of Metarhizium spp. obtained from the Central American locust (Schistocerca piceifrons piceifrons). The isolates MaaPL16, MaaPL25 and MaPL40 are among the most virulent.

A comparative analysis on Random Amplified Polymorphic DNA patterns between two Mexican isolates of Metarhizium, MaPL40 and MaPL32, and an Australian isolate of Metarhizum anisopliae var. acridum (FI-985), showed that the Mexican isolates and the Australian isolate have similar DNA fingerprints, suggesting they may belong to the same variety.

Field trials using oil formulations of the MaPL40 and MaPL32 isolates against hopper bands of S. piceifrons piceifrons, applied at a rate of 50g of conidia in oil, 1 l ha⁻¹, provided >90% reduction in the hopper bands 10 d after treatment. Comparative studies between the Mexican and the Australian isolates were conducted over a range of temperatures: results are reported in detail.

With the trend towards crop diversification, there has been a gradual increase in production of crucifer oilseed crops (canola and mustard) in the Prairie Ecozone of western Canada. Developments in germplasm of Brassica spp. and Sinapis alba L. have resulted in cultivars with improved drought resistance, making them more acceptable for production in arid regions of the prairies. This, in turn, has resulted in increased overlap in areas of grasshopper infestation and oilseed production. Grasshoppers are the most chronic insect pests of annual crops in the Prairie Ecozone. The primary threat to production of annual crops arises from migration of the hatchling populations into cropland from roadsides, headlands and field margins at the beginning of the growing season. As a result, grasshopper damage is most acute at the early stages of crop growth.

In this study, the impact of early season grasshopper feeding on canola and mustard crops was quantified in field studies, 1996 to 1998. Immatures of Melanoplus sanguinipes (the lesser migratory grasshopper) were allowed to damage eight Brassicaceae cultivars and breeding lines of four species: Brassica juncea Czern (‘AC Vulcan’ and ‘J92-223’), B. napus (‘AC Excel’ and ‘Midas’), B. rapa (‘AC Parkland’ and ‘Echo’) and S. alba (‘AC Pennant’ and ‘Ochre’). The overall yields of defoliated plants were 27.8% less than those of control plants (p = 0.0001). Yield reductions were greatest for AC Excel (47%) and least for AC Vulcan (19.6%). The results are discussed in the context of grasshopper management strategies.

The species of cricket Cicloptyloides americanus has males with 2n = 14 and females with 2n = 16 chromosomes. The autosomes are metacentrics and the sex determining mechanism is of the X₁X₂O (male) – X₁X₁X₂X₂ (female) type, with X₁ submetacentric and X₂ acrocentric. This mechanism is cited for the first time among species belonging to the order Orthoptera.