Common Grasshopper Research Articles

Conservation of grasshopper diversity in a changing environment

Land-use change is a major driver for changes in biodiversity. In this study, we investigated how the objectives of two conservation strategies (large-scale conservation of species richness versus conservation of diversity hotspots) can be achieved for grasshopper diversity under different scenarios of environmental change (land-use and climate change). Based on surveys of 95 grasshopper species from 2001 to 2004 recorded by the Swiss Centre for Faunal Cartography, we modelled the actual richness pattern as a function of different environmental variables. The impact of potential future environmental change on species richness was evaluated by applying four land-use scenarios (‘liberalization’, ‘business as usual’, ‘lowered agricultural production’, and ‘complete conversion of intensive open land’) and one climate change scenario. The effects of the scenarios were assessed at the national scale, as well as on small-scale hotspots. Environmental change has considerable effect on grasshopper species richness. At the national scale, the number of grasshopper species decreased under the ‘liberalization’ scenario (−0.24 species per 1 ha pixel) and increased under a climate change scenario (+0.63 species per 1 ha pixel). For most environmental change scenarios, species richness in small-scale hotspots was more negatively affected than on average on the national scale. The response of species richness to the scenarios did not differ significantly between hotspots of endangered and the hotspots of common grasshopper species. We conclude that conservation efforts at the national scale and small-scale hotspot conservation programs should be combined to conserve species richness most successfully. For the long-term conservation of species richness, common species as well as the combined effects of land-use and climate change have to be considered.

Competition among the adults of three grasshoppers (Orthop., Acrididae) on an alpine grassland

Abstract: The intraspecific and interspecific competition among the adults of three common grasshoppers, Angaracris rhodopa (Fischer‐Waldheim), Chorthippus dubius (Zubovsky) and Chorthippus fallax (Zubovsky) was investigated on Ganjia High Mountain Grassland in north‐west China. The results indicated a strong intraspecific competition within species at high densities. The interspecific competition between the larger‐sized species, A. rhodopa, and the smaller‐sized species, C. dubius or C. fallax, was weak, while competition between C. dubius and C. fallax was strong. An asymmetric competitive interaction in mortality and fecundity associated with the diet and size was observed among the three species. Competition was strong between the two species that had a similar diet. The large‐sized species had higher mortality rates and lower fecundity than the smaller‐sized species. Intraspecific competition between the three species was mainly affected by food limitation, while interspecific competition was mainly associated with food limitation as well as the grasshoppers’ adaptation to the environment.

Hotspots and richness pattern of grasshopper species in cultural landscapes

The success of the hotspot approach for biodiversity conservation depends on the spatial scale and the indicator species used. In this study, we investigated grasshopper species richness in Switzerland at a 1 ha resolution including a total of 111 species. We compared the representativeness of common and of endangered grasshopper species for the overall grasshopper species richness and we assessed the efficiency of the hotspot approach for grasshopper conservation. The pattern of overall grasshopper species richness was well represented by both the number of common and the number of endangered grasshopper species. For evaluating the efficiency of different hotspot approaches for conservation, we compared hotspots of common species, hotspots of endangered species (rarity hotspots), and hotspots of all grasshopper species (richness hotspots). Among these hotspot types, richness hotspots not only featured most common grasshopper species, but they even contained more endangered species than the rarity hotspots. The combination of rarity hotspots and hotspots of common species featured more species than the other combinations of hotspot types. However, the gain of combining two hotspot types compared to the single-hotspot approach was low (max. 3 species). About 24% of the species were not contained in any of the hotspots. These grasshopper species require species-specific action plans. As rarity hotspots were located in areas that are rather strongly affected by landscape change, species richness in rarity hotspots may decrease in the future. We conclude that, for grasshoppers, the hotspot approach on the 1 ha scale can be an effective way to conserve a high proportion of species richness.

Natural History of Mass-action in Predator-prey Models: A Case Study from Wolf Spiders and Grasshoppers

Abstract Mass-action models of predator-prey interactions assume that predators encounter prey according to their relative densities as scaled by functional responses, although models seldom specify critical natural history and behavioral mechanisms that ensure that encounters actually occur. As a case study of this assumption, we assess the hypothesis that daily and seasonal activity and microhabitat use by wandering wolf spiders (Lycosidae: Schizocosa) searching for four common grasshopper species (Orthoptera: Acrididae) are coincident under natural conditions. There was great overlap in seasonal phenology and use of microhabitats between spiders and grasshoppers. Grasshoppers that were suitably sized (10–20 mm in length) as prey for spiders were relatively abundant from late spring through summer in this grassland. Three of the four common grasshopper species used microhabitat in a similar way, but differed from a fourth common species, Phoetaliotes nebrascensis. However, when they were active, spiders...

The Diet of Nestling Abdim's Stork Ciconia abdimii in Niger

Although the Abdim's Stork (Ciconia abdimii) is a common breeder in the Sahel zone across Africa, its diet during the breeding season has never been studied. Chick meals were sampled in stork nests in West and Central Niger during early July and late August, representing early and mid rainy seasons in the area. The diet consisted of amphibians (Bufo sp.) and a range of insects with grasshoppers (Orthoptera) as the dominant (23 species) group making up 30% and 59% of prey biomass in July and August, respectively. In terms of frequency of occurrence, the important Sahelian pest species Oedaleus senegalensis was the most common grasshopper in the stork chick diet. There was a marked seasonal difference in the relative importance of insects and vertebrates: in July amphibians made up 61% of diet by wet weight, and insects 38%, while in August insects made up 92% of prey wet weight, and amphibians only 6%. The high dependency on amphibians in July was a surprise, but suggests that toads may be the key prey for the adult storks during the incubation period when toads become active while major new insect generations have not yet emerged. The increased importance of insects later in the rainy season reflects the emergence of new generations of grasshoppers, where, in particular, the locally (too) abundant Oedaleus senegalensis becomes the main prey.

PLANT QUALITY AND SPIDER PREDATION AFFECTS GRASSHOPPERS (ACRIDIDAE): FOOD-QUALITY-DEPENDENT COMPENSATORY MORTALITY

For insect herbivores, population responses reflect interactions among multiple factors, including abiotic conditions, food plant availability, and biotic interactions guided by food limitation and natural enemies. In this set of field experiments, we evaluated the interactive, dynamic effects of limited food supply and predation from wolf spiders (Lycosidae) on mortality in Ageneotettix deorum, a common grasshopper (Acrididae) from North American sandhills grasslands. We attempted to determine whether the combined effects of food availability and spider predation on mortality were (1) noncompensatory, with the effects of each factor summing to determine ultimate population size, or (2) compensatory, where the effect of one mortality factor alters the impact of subsequent factors so that the ultimate population size changes little, despite variation in specific sources of mortality. We also investigated whether changes in nutritional quality encountered by grasshoppers would result in different dynamic responses to predation in the context of noncompensatory vs. compensatory responses. Both food availability and predation risk contributed to mortality rates. Individuals of A. deorum were food limited. Survival of grasshoppers feeding on fertilized plants was 50% higher than that of grasshoppers feeding on unfertilized plants over a 31-d period. Most of the mortality due to limited food occurred 12–14 d into the experiment. Predation from lycosid spiders decreased the numbers of individuals by 49% in the first 10–15 days of the experiment. Either noncompensatory or compensatory responses resulted from the combined effects of food availability and predation on population size, depending upon the nutritional status of host plants. At ambient-level food quality (no fertilizer), spider predation and food limitation were compensatory; the same numbers of grasshoppers were recovered in treatments with and without spider-predation risk after 31 d. However, with higher food quality (N fertilizer), spider predation reduced the numbers of surviving individuals as compared with the no-spider-predation treatment, a noncompensatory response. In separate, preplanned experiments, individuals surviving spider-predation treatments lived longer than did individuals protected from spider predation when they were caged individually over vegetation of ambient quality. Combined, these experiments emphasize the importance of food quality as a determinant of how this predator–prey system responds, and the results suggest a mechanism underlying the response. After predation, survivors are likely to encounter more food per capita and to exhibit higher individual quality, which promotes longevity, presumably from reduced competition. This leads to a compensatory response. Under high food quality regimes, predation and food probably act in a noncompensatory fashion because grasshoppers are less food limited, and the release of additional food on a per capita basis by predation has less effect on the subsequent number of survivors.

Habitat Relationships Among Grasshoppers (Orthoptera:Acrididae) at the Western Limit of the Great Plains in Colorado

Abstract We measured grasshopper densities on 66 shortgrass, mixed grass, tallgrass and hayfield plots on Boulder, Colorado, open space in 1995–1996. Grasshoppers as a group, and most species individually, were more abundant on relatively sparse short and mixed grass plots than on lusher hayfields and tallgrass plots—a result consistent with the hypothesis that most species require warm and sunny open ground for survival and reproduction. Bandwinged grasshoppers (Oedipodinae) were particularly associated with open ground in shortgrass vegetation, whereas spur-throated grasshoppers (Melanoplinae) were most abundant in mixed grass plots with a high percentage of forb vs. graminoid cover. Slant-faced grasshoppers (Gomphocerinae) were the most uniformly distributed among habitats, but were generally associated with plots including relatively high proportions of grass vs. forb cover. While 20 of the 25 most common grasshopper species on Boulder open space occurred in all four grassland types, each habitat was ...

Stage-based mortality of grassland grasshoppers (Acrididae) from wandering spider (Lycosidae) predation

Abstract Mortality rates in insects, including grasshoppers (Acrididae), are often stage- or size-specific. We estimated stage-specific mortality rates for three common grasshopper species from a Nebraska (USA) sandhills grassland ( Ageneotettix deorum, Melanoplus sanguinipes and Phoetaliotes nebrascensis ), and partitioned the impact due to wandering spider predation from remaining sources. Survivorship was estimated for multiple developmental stages (3rd instar through adult) under experimental conditions that either prevented or permitted predation from free-living, wandering spiders (primarily Schizocosa species). Total stage-specific mortality, including spider predation, examined over the period of single stages was greatest for the youngest stages (91% for 3rd instar, 73% for 4th instar, 63.5% for 5th instar and 30.4% for adults). For the developmental stages considered and averaged for all species, the contribution to total mortality from spider predation over the 10-d period (approximately the length of a developmental stage) ranged from 17% for 3rd instar nymphs to 23% for 4th and 5th instars, and an undetectable level for adults. While spiders may depress grasshopper numbers, contributions from spider predation to grasshopper population dynamics are uncertain.

Suitability of Legume Cover Crops for Grasshopper (Orthoptera: Acrididae) Development and Reproduction

The use of legume cover crops is a potentially valuable practice in mitigating problems associated with annual crop-fallow rotations in the Northern Plains. Because grasshoppers may become a pest in a cover crop system, we determined the suitability of 4 annual legumes for grasshopper development and reproduction. No-choice diets of grass pea (Lathyros sativus L.), lentil ( Lens culinaris Medikus), field pea ( Pisum sativum L.), and hairy vetch (Vicia villosa Roth) were fed to 5 species of grasshoppers: Melanoplus bivittatus (Say), Melanoplus differentialis (Thomas), Melanopltls femtlrrubrum (De Geer), Melanoplus packardii Scudder, and Melanoplus sangllinipes (F.). Field pea and lentil were the least suitable legumes when considering the combination of grasshopper survival, development, and reproduction. The effect was most pronounced for M.sanguinipes and M. femurrubrum. These grasshoppers displayed poor survival and delayed development when fed field pea or lentil compared with other legumes or a control. Adult fecundity and fertility of eggs also were adversely affected when no-choice diets of field pea or lentil were offered. For M.packardii, a nymphal diet of field pea resulted in the poorest development; grasshoppers fed an adult diet of field pea did not reproduce. M. bivittatus and M. differentialis experienced limited mortality when fed field pea or lentil. Nevertheless, development was substantially delayed and reproduction inhibited to varying degrees. Field pea and lentil appear to have good potential in providing the benefits of cover crops, while decreasing the economic impact of common grasshopper species.

Ecological Correlates Between Rangeland Grasshopper (Orthoptera: Acrididae) and Plant Communities of Southern Idaho

Grasshopper and plant community relationships in southern Idaho were examined within a life–history context. Plant species composition (by weight) and density and species composition of grasshoppers were estimated at 52 sites in south–central Idaho, representing a range of plant communities from native sagebrush–bunchgrass to exotic annual grasslands.The plant community at each site was evaluated using the Grime triangular model of plant life–history strategies,which consists of 3 axes representing adaptations to competition, stress, and disturbance. Four attributes were measured for the 20 most common grasshopper species: mean density, habitat breadth, average instar in June, and diet breadth. Grasshopper density, habitat breadth, and diet breadth were correlated positively with site scores on the disturbance axis of the Grime life–history model and were correlated negatively with site scores on the competition and stress axes. Results suggest that characterization of grasshopper and plant community life–history strategies provides useful insights for understanding the dynamics of grasshopper assemblages from different habitats.

Effects of Bird Predation on Grasshopper Densities in an Arizona Grassland

In a 4—yr field experiment, we tested the hypotheses that insectivorous birds (1) controlled densities of herbivorous grasshoppers in an ungrazed semiarid grassland in southeastern Arizona, and (2) functioned as keystone predators, by limiting abundances of grasshoppers that otherwise might change vegetation cover and species composition, and/or by mediating the effects of otherwise competitively superior members of the grasshopper assemblage. We measured grasshopper densities and vegetation on 32 464—m2 grassland plots for 1 yr, then enclosed 16 of these plots with bird exclosures and continued data collection for 3 yr. Eight of the 16 experimental plots were further modified in the last 2 yr of the study by installing fine—mesh 1 m high barriers designed to retard grasshopper dispersal. Microclimates of caged plots differed only slightly from open plots. Lizards and rodents increased inside the exclosures, but they were removed and released elsewhere such that their average abundances did not differ among treatments. By the final year of the study, mean annual adult grasshopper density was >2.2 times higher on plots from which birds were excluded, and where grasshoppers were enclosed by dispersal barriers, than on unmanipulated control plots. Mean nymph density was >3.0 times higher in the same comparison. Grasshoppers were significantly more abundant in bird exclosures with insect dispersal barriers, indicating that experimental plots were dispersal sources rather than sinks. Seven of 12 common grasshopper species were more abundant inside the bird exclosures, while none was less abundant. Among the more abundant taxa, those responding most positively were grass feeders: Eritettix simplex, Opeia obscura, Paropomala wyomingensis, and Phoetaliotes nebrascensis. We found no evidence that grasshoppers competed with one another under increased densities inside the bird exclosures. Although the amount of insect herbivory was somewhat higher inside the bird exclosures, and was positively correlated with grasshopper density across all 32 plots (r = 0.87), overall vegetation cover and species composition did not differ among treatments by the end of the study. Dactylotum variegatum, an aposematic species apparently immune to avian predation, showed no significant responses to the experiment. Birds clearly limited grasshoppers in this grassland ecosystem, but they failed to qualify as keystone predators, at least in the short term, for two reasons: (1) in their absence, increased grasshopper densities had no appreciable impact on vegetation cover or species composition; and (2) there was no evidence that birds mediated competition among grasshoppers.

Consumer-producer relationships for trace metals in Chorthippus brunneus (Thunberg).

The behavior of trace metals in terrestrial food chains is a subject of ecological interest, particularly in polluted environments where the potential exists for bioconcentration of metals known to be essential in trace amounts for normal plant and animal metabolism, as well as those with no known metabolic function but recognized toxicological properties. Laboratory studies of food chain relationships afford a means by which direct comparisons can be made between trace metals as a basis for interpretation of data collected from wild plant and animal populations. This study compares the behavior of three trace elements, copper, zinc and cadmium, in terms of their assimilation under experimental conditions by the herbivorous common field grasshopper, Chorthippus brunneus (Thunberg.). This voracious orthopteran is widely distributed in Britain and is particularly prominent in the restricted invertebrate community of some metal smelter-affected grasslands where it forms important seasonal prey for insectivorous small mammals.

The Suitability of Legumes for Rangeland Interseeding and as Grasshopper Food Plants

The Suitability of Legumes for Rangeland Interseeding and as Grasshopper Food Plants

Electron microscopic study of the spermatheca ofGesonula punctifrons (Acrididae: Orthoptera)

The present transmission electron microscopic study of the spermatheca of a common Indian grasshopper,Gesonula punctifrons, has highlighted the presence of the glandular secretory cells (SGC) and ductule cell (DC) in the spermathecal epithelium and additionally the occurrence of muscle cells, tracheoles and haemocytes. Both the former cell types are secretory in nature and probably their discharges in the lumen of the cuticle-lined spermathecal duct or ductule vary in their chemical nature. The ultrastructural evidence gives ample support to a concept of a lysosomal control of the secretory materials prior to their liberation in the lumen. The characteristic features of the plasma membranes of the secretory cells clearly suggest their involvement in the transepithelial transport of ions and smaller molecules across the basement membrane. A neuronal supply to the spermathecal wall is yet to be demonstrated to explain the filling in and out of the male gametes by this organ.

The food and feeding habits of Eutropius niloticus (Ruppell), family Schilbeidae (Osteichthyes: Siluriformes) in Lake Kainji, Nigeria

Studies on the food and feeding habits of Eutropius niloticus in Lake Kainji, Nigeria revealed that the fish is omnivorous but fed more on insects than on any other food. The most important insects were Povilla adusta Navas nymphs and imagos and adults of the common grasshoppers. Fish, particularly the clupeids Sierrathrissa leonensis Thys Van den Audernaerde and Pellonula afzeliusi Johnels, also formed an important part of the diet. There was seasonal variation of organisms selected for food and there were variations in the dietary items selected by different age groups. Accumulation of fat was found to correlate with seasonal feeding intensity. E. niloticus serves as food for other fishes.

Insect herbivory on C3 and C4 grasses.

This study tested the hypothesis that grasses with the C4 photosynthetic pathway are avoided as a food source by insect herbivores in natural communities. Insects were sampled from ten pairs of C3-C4 grasses and their distributions analyzed by paired comparisons tests. Results showed no statistically significant differences in herbivore utilization of C3-C4 species. However, there was a trend towards heavier utilization of C3 species when means for both plant groups were compared. In particular, Homoptera and Diptera showed heavier usage of C3 plants. Significant correlations between insect abundances and plant protein levels suggest that herbivores respond to the higher protein content of C3 grasses. δ13C values for six of the most common grasshopper species in the study area indicated that three species fed on C3 plants, two species fed on C4 plants, and one species consumed a mixture of C3 and C4 tissue.

Experimental Studies on the Choice of Oviposition Sites by Two Species of Chorthippus (Orthoptera: Acrididae)

It has been observed that most acridid species have restricted oviposition sites. In some species the soil relation is very pronounced while in others it is not so well marked or may be altogether absent. Vestal (1913), Smith (1915), Severin & Gilbertson (1917), Criddle (1918, 1933), Rubtzov (1935), Shotwell (1935), Weddel (1937), Zimin (1938), Watson & Bartley (1940), Clark (1949), Waloff (1950) and Richards & Waloff (1954) have described the selection of egg-laying sites in grasshoppers inhabiting fields, meadows, pastures and sandy heaths. Some workers like McClung (1899), Rubtzov (1935), Knutson (1937), Iseley (1938) and Professor George J. Spencer (private communication) have also attempted to study experimentally and to analyse the factors responsible for such selection in grasshoppers. Experimental studies on the selection of oviposition sites by several locust species have been made by Johnston & Maxwell-Darling (1931), Faure (1932), Kennedy (1949), Znamenskii (1951) and Choudhuri (1956a, b). Observations on the experimental studies on the choice of oviposition sites by two common British grasshoppers, Chorthip_pus parallelus (Zett.) and C. brunneus (Thunb.) are reported here.

The Phases of the Rocky Mountain Locust Melanoplus Mexicanus (Saussure)

Dr. Faure has shown experimentally (1932) that the brown locust, Locustana pardalina, of South Africa exists under two phases, the solitary phase and the swarm phase. Each of the individuals of the solitary phase, which live in isolation like most common grasshoppers, is a representative form of the phase solitari-r. Each of the individuals of the swarm phase, which come together in great dense swarms and then migrate over the country, is a representative of the phase gregari-r. The nymphs of the phase gregaria differ markedly from the nymphs of the phase solitaria in coloration, while the adults of gregaria differ in several morphological characters from the adults of the phase solitaria. Dr. Faure, by means of an ingenious series of experiments, has been able to transform the progeny of the solitaria phase into the phase gregaria. There is, therefore, now no doubt of the fact that the transformation of this grasshopper from one phase into the other phase occurs in nature when the conditions are present to bring it about. It has been suggested recently by several authors that our Rocky Mountain locust Melan-oPlus spretus, now apparently extinct, was the long winged migratory (gregaria) phase of our common grasshopper Melan-oplus (atlanis) mexican-us. Dr. Faure conceived the idea of attempting, by his experimental methods used so successfully with the brown locust of South Africa, to transform M. mexican-us which he surmised to be the solitaria phase into M. spretus, the phase gregaria. The following paper embodies the results of Dr. Faure's observations on M. mexican-us in rearing experiments carried out at Saint Paul, Minnesota, during l\'lay, June, and July 1932.

The Anatomy of the Digestive System of the Carolina Locust (D. carolina, Linn).*

The typical insect dissected by most students in biology is the Carolina locust or some other common grasshopper. While many laboratory manuals describe the anatomy of these orthopterons in more or less detail, few if any, are adequately illustrated. Lack of illustration makes it difficult for the instructor to present the subject and leads to confusion in the minds of the students. It is the aim of this paper to meet this need in part by presenting in its text and figures the results of a detailed study of the alimentary tract of the Carolina Locust.