Data Paper |
Corresponding author: Jin-Long Ren ( rjlinsect@163.com ) Corresponding author: Li Zhao ( zlym57@sohu.com ) Academic editor: Michel Lecoq
© 2024 Jin-Long Ren, Wen-Jing Kang, Jin-Xing Li, Xi Jin, Ke-Xin Li, Li Zhao.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Ren J-L, Kang W-J, Li J-X, Jin X, Li K-X, Zhao L (2024) Food-plant choice of seven dominant grasshopper species in the Xinjiang grasslands. Journal of Orthoptera Research 33(1): 157-168. https://doi.org/10.3897/jor.33.110690
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Feeding habits and competitive interactions among dominant grasshopper species in the Xinjiang grasslands (China) were studied under natural conditions through microscopic analyses of insect crop contents. Sex-specific and interindividual differences in feeding habits and interspecific competition were investigated. Analyses of ecological niche width and overlap revealed potential competition among grasshoppers. The results showed significant difference in the sex-specific variations in the feeding habits of the seven grasshoppers; sex-specific variations in feeding range and preferred plants were observed, with females feeding more extensively on host plants, and female and male adults choosing to feed on different plant species. Individuals of all seven grasshoppers showed different degrees of dietary variance, with oligophagous grasshoppers (Oedaleus decorus males, Dericorys annulata, and Bryodema gebleri males) showing a smaller degree of individual dietary variance than polyphagous grasshoppers (Oedipoda caerulescens, Calliptamus coelesyriensis females, Calliptamus barbarus, and Notostaurus albicornis); Calliptamus coelesyriensis and Notostaurus albicornis showed the greatest individual variance in their diets. Oedaleus decorus, Bryodema gebleri, and Calliptamus barbarus consumed primarily Poaceae and exhibited varying foot-plant choice. For example, Oedaleus decorus was observed to have high- preference feeding for Poa annua, Bryodema gebleri for Stipa capillata, and Calliptamus barbarus for Setaria viridis. Dericorys annulata fed primarily on Amaranthaceae, Notostaurus albicornis fed primarily on Poaceae and Amaranthaceae, and Oedipoda caerulescens fed primarily on Asteraceae. Calliptamus barbarus exhibited strong interspecific competition with Oedaleus decorus and Calliptamus coelesyriensis, and Bryodema gebleri demonstrated the strongest interspecific competition with all six other species. Considering the influence of sex on interspecific competition among grasshoppers enhances our understanding of interspecific competitive relationships.
caelifera, diet, intraspecific competition, individual variation, sex
Grassland ecosystems are among the most significant on Earth (
Xinjiang, located in the western part of China’s northern grasslands, has a grassland area of 57.7 million hectares, making it the region with the third-largest area of grasslands in China. The province is among those with the richest grassland resources in China (
Several dominant species of grassland grasshoppers, including Oedaleus decorus, Oedipoda caerulescens, Bryodema gebleri, Calliptamus coelesyriensis, Calliptamus barbarus, Dericorys annulata, and Notostaurus albicornis, have been identified in Xinjiang (
Food preference plays a crucial role in determining herbivores’ diets and spatial distributions (
Research on grasshopper species using MACC has been conducted in Inner Mongolia (
Insects exhibit distinct patterns of host-plant feeding that vary between the sexes and among individuals (
In this study, the grasshoppers were collected in July of 2018, and predation observations and analysis were conducted from 2019–2022. We hypothesized that the magnitude of inter-individual feeding differences is related to the range of grasshopper feeding. For this reason, we selected three oligophagous grasshoppers and four polyphagous grasshoppers known to be present in Xinjiang, China, investigated their feeding status under natural conditions, and utilized crop inclusion microanalysis to study the feeding differences between the two sexes in each species and among individuals and species. We also analyzed the feeding frequency, ecological niche width, and degree of overlap to clarify the feeding status of the sexes, individuals, and species among the seven grasshoppers..
Study site and species.—Based on an examination of the grasslands in the Bozhou region of Xinjiang, China, we selected six natural grassland study sites that are not artificially managed. Collecting was done in the summer of 2018. In each sample plot, a net was swung 100 times in each of four directions (east, south, west, and north); each net was spaced 2 m apart. We identified grasshoppers visually, and 10 females and 10 males of each species were randomly selected and collected for crop inclusion microanalysis. The present study reports on grasshoppers from seven species belonging to two families (Acrididae and Dericorythidae) and three subfamilies (Oedipodinae, Calliptaminae, and Gomphocerinae) of the Acrididae. The species collected were Oedaleus decorus, Oedipoda caerulescens, and Bryodema gebleri from the Oedipodidae; Calliptamus coelesyriensis, and Calliptamus barbarus from the Calliptaminae; Dericorys annulata from the Dericorythidae; and Notostaurus albicornis from the Gomphocerinae. Table
Grasshoppers | Plants | |||||||
---|---|---|---|---|---|---|---|---|
Family | Subfamily | Species | Collection site (city) | Relative abundance in the point | Acquisition time (Y.M.D) | Dominant species | Non-dominant species | Vegetation cover of the point (%) |
Acrididae | Oedipodinae | Oedaleus decorus (Germar, 1825) | Ku Si Mu Qie Ke (Bole) | 68.2% | 2018.7.26 | Seriphidium borotalense | Anabasis sp., Nanophyton erinaceum, Stipa capillata | 45%–50% |
Bryodema gebleri (Fischer von Waldheim, 1836) | Tuo Si Gou((Wenquan) | 34.13% | 2018.7.31 | Nanophyton erinaceum, Seriphidium borotalense | Anabasis sp., Astragalus membranaceus, Carex sp., Nanophyton erinaceum, Peganum harmala, Polygonum aviculare, Stipa capillata | 15%–20% | ||
Oedipoda caerulescens (Linnaeus, 1758) | Xiao Hai Zi (Jinghe) | 13.4% | 2018.7.25 | Caragana sinica, Festuca ovina, Stipa capillata, weeds | Achillea millefolium, Artemisia frigida, Artemisia sieversiana, Avena sativa, Berberis amurensis, Cirsium arvense, Cirsium arvense, Inula rhizocephala, Juniperus sabina, Leontopodium leontopodioides, Neotrinia splendens, Poa annua, Polygonum aviculare, Setaria viridis, Taraxacum mongolicum, Urtica fissa | 75%–80% | ||
Calliptaminae | Calliptamus coelesyriensis Giglio-Tos, 1893 | Xiaoyingpan 1 Ranch (Bole) | 43.82% | 2018.7.24 | Seriphidium borotalense | Atraphaxis spinosa, Ceratocarpus arenarius, Lactuca tatarica, Peganum harmala, Poa annua | 15%–20% | |
Calliptamus barbarus (Costa, 1836) | Ranch No. 1, Qingxiang, Yamatan (Bole) | 21.02% | 2018.7.24 | Seriphidium borotalense | Caragana sinica, Ceratocarpus arenarius, Nanophyton erinaceum, Peganum harmala, Poa annua, Setaria viridis | 15%–20% | ||
Gomphocerinae | Notostaurus albicornis (Eversmann, 1848) | Ranch No. 1, Qingxiang, Yamatan (Bole) | 41.42% | 2018.7.24 | Seriphidium borotalense | Caragana sinica, Ceratocarpus arenarius, Nanophyton erinaceum, Peganum harmala, Poa annua, Setaria viridis | 15%–20% | |
Dericorythidae | Dericorys annulata (Fieber, 1853) | Alashankou Reservoir (Alashankou) | 39.37% | 2018.7.23 | Anabasis cretacea, Kali collinum, Seriphidium borotalense | Bassia prostrata, Haloxylon ammodendron, Krascheninnikovia ceratoides, Neotrinia splendens, Stipa capillata, Suaeda glauca | 10%–15% |
Dietary analysis.—The experiment was conducted using adult grasshoppers immediately killed with a 75% ethanol solution and transported to the laboratory. Microscopic analysis of the grasshoppers’ crop contents was then conducted to determine food choices. By comparing the plant fragments collected from the crops with those obtained from voucher specimens collected in the study area (
Data analysis.—The relative frequency of feeding (RFN) was calculated using Li’s (1983) measure:
where X is the number of times in which a plant is found in an individual insect’s anatomical samples and ∑x is the total number of times in which all plants are found in an individual insect’s crop.
Grasshopper feeding was classified into four categories according to RFN values: RFN > 0.5 was considered “high-preference feeding,” RFN of 0.5–0.25 was considered “preference feeding,” RFN of 0.25–0.024 was considered “seldom feeding,” and RFN < 0.024 was considered “occasional feeding.” The degree of grasshoppers’ preference for feeding on plants was defined accordingly (
To determine species niche breadth, we used Levin’s measure (1968):
where B represents Levin’s measure of food niche breadth and pi denotes the proportion of the food i consumed by a species among all foods consumed.
We used Schoene’s measure (1970) to calculate species niche overlap:
where Cih represents the degree of niche overlap between species i and h, Pij is the number of times in which plant i is found among all anatomical samples of insect species j, and Pik is the number of times in which plant i is found among all anatomical samples of insect species k. Cih varies from 0 to 1, with 0 representing no overlap and 1 representing complete overlap; Cih > 0.6 is generally considered biologically significant (Colwell 1971, Li Yunkai et al. 2021).
Overlap among food ecological niches was defined by two or more species with similar ecological niches sharing or competing for common resources while living in the same space. The degree of niche overlap was expressed by the Cih index (Colwell 1971).
Statistical analysis.—We used SPSS (version 19; SPSS Inc.) on a personal computer for all statistical analyses. To test whether male and female grasshoppers differ in feeding ecology, we performed a multivariate analysis of variance (MANOVA) with sex as the sole factor and host plant as the dependent variables (
Dietary composition.—The seven grasshopper species had ingested a total of 33 distinct botanical species (Figs
Relative feeding frequency (RFN) of seven grasshopper species on plants, showing different feeding levels. The absence of circles means that the plants are not eaten. After the grasshoppers’ species names, F = female, M = male and A= female+male. The horizontal bars separate distinct taxonomic groups of plants.
Food preference.—Sex variation. As indicated in Figs
Significant differences in high-preference feeding on plants between male and female adults were observed in the seven grasshopper species (Fig.
Through MANOVA on the RFN of botanical specimens consumed by both sexes of grasshoppers, it was established that Oedaleus decorus females fed significantly more strongly on Psathyrostachys juncea and Poa annua than their male counterparts (P = 0.002, 0.000 < 0. 01), and females fed significantly less on Stipa capillata than their male counterparts (P = 0.000 < 0.01). Bryodema gebleri females fed significantly more strongly on Suaeda glauca than males (P = 0.004 < 0.01), but significantly less on Stipa capillata than males (P = 0.000 < 0.01). Oedaleus caerulescens females fed significantly more strongly on Artemisia scoparia than males (P = 0.009 < 0.01), and females fed significantly less on Artemisia sieversiana than males (P = 0.005 < 0.01). Calliptamus coelesyriensis females fed significantly more strongly on Caragana sinica and Peganum harmala than males (P = 0.007 < 0.01 and P = 0.026 < 0.05, respectively) but significantly less on Ceratocarpus arenarius than males (P = 0.000 < 0.01). Calliptamus barbarus females fed significantly more on Setaria viridis than males (P = 0.009 < 0.01) but significantly less on Festuca ovina, Ceratocarpus arenarius and Caragana sinica than males (P = 0.035 < 0.05 and P = 0.002, 0.002 < 0. 01, respectively). Dericorys annulata females fed significantly less on Bassia prostrata than males (P = 0.042 < 0.05). Notostaurus albicornis females fed significantly more on Bassia prostrata than males (P = 0.006 < 0.01) but significantly less on Ceratocarpus arenarius, Stipa capillata and Seriphidium borotalense than males (P = 0.026, 0.020 < 0.05 and P = 0.003 < 0. 01, respectively).
Interindividual variation. The individual feeding habits of the seven species of grasshoppers are shown in Fig.
Dietary specialization. Insects exhibit different degrees of specialization in their feeding habits, ranging from monophagy to oligophagy to polyphagy. In this study, it was found that whether Oedaleus decorus, Bryodema gebleri, and Calliptamus coelesyriensis were oligophagous or polyphagous depended on their sex: females showed polyphagous behavior while males showed oligophagous behavior. The rest of the grasshoppers showed the same behavior in males and females; for example, Dericorys annulata was oligophagous and Oedipoda caerulescens, Calliptamus barbarus, and Notostaurus albicornis were polyphagous (Fig.
Niche analysis.—Sex variation in ecological niches. Next, we performed t-tests to determine the ecological niche widths of male and female grasshoppers across seven locations. Only Oedaleus decorus, Bryodema gebleri, Oedipoda caerulescens, and Calliptamus coelesyriensis displayed a notable variance in sexual dimorphism. The feeding ecological niches of female Oedaleus decorus and Calliptamus coelesyriensis were significantly wider than those of their male counterparts (P = 0.019, 0.037 < 0.05), and for female Bryodema gebleri, the niche was highly significantly wider than for their male counterparts (P = 0.004 < 0.01), whereas the male feeding ecological niches of Oedipoda caerulescens were highly significantly wider than those of the females (P = 0.006 < 0.01) (Fig.
Comparison of ecological niches. Among the seven grasshopper species, Notostaurus albicornis and Oedaleus decorus exhibited significantly greater niche widths (P < 0.05), measured at 5.22 and 4.02, respectively (Fig.
Herein, we present the results of using MACC to examine sex-specific, interindividual, and interspecies differences in dietary patterns in seven grasshopper species present in the Xinjiang grasslands. Previously, it was reported that Oedaleus decorus and Bryodema gebleri were oligophagous and Calliptamus coelesyriensis was polyphagous. In the present study, we found that whether Oedaleus decorus, Bryodema gebleri, and Calliptamus coelesyriensis are oligophagous or polyphagous depends on their sex, such that the females are polyphagous and the males are oligophagous, which has not been reported previously. There were significant sex differences in the feeding habits of the seven grasshoppers, and females displayed a greater tendency to consume more host plant species than males. In addition, adults displayed sex-specific differences in high-preference food sources. Individuals of all seven grasshoppers showed different degrees of dietary variance, with oligophagous grasshoppers (Oedaleus decorus males, Dericorys annulata, and Bryodema gebleri males) showing a smaller degree of individual dietary variance than polyphagous grasshoppers (Oedipoda caerulescens, Calliptamus coelesyriensis females, Calliptamus barbarus, and Notostaurus albicornis) and Calliptamus coelesyriensis and Notostaurus albicornis showing the strongest individual variance in their diets. Oligophagous individuals were present in polyphagous grasshoppers (Oedaleus decorus females, Calliptamus coelesyriensis females, Oedipoda caerulescens females, and Notostaurus albicornis females); monophagous individuals were present in oligophagous grasshoppers (Oedaleus decorus males, Bryodema gebleri males, Calliptamus coelesyriensis males, and Dericorys annulata).
Host plant preference.—In a study on the dietary habits, trophic specialization, and degree of trophic specialization exhibited by 65 species of grasshoppers in the lower Volga River region of Russia,
Grasshoppers more closely related often exhibit more similar feeding habits (
Our findings, combined with previous findings on grasshopper feeding patterns, indicate that Oedaleus decorus exhibits a high-preference feeding on Poaceae (Poa annua) (
We observed significant differences in the feeding habits of the sexes. We speculate that these differences might be attributable to the heavier body weight of female grasshoppers as well as their choice for laying eggs on the ground, thus resulting in the tendency of adult females to move along the lower parts of plants or on the ground surface more frequently than males (
Considerable interindividual variation in feeding on host plants exists among insects (
The feeding habits of grasshoppers are related to the insect’s body (the grasshopper itself) and the plant. Where genetic variation in the insect body itself determines its feeding choices (
Grasshopper feeding choice is a complex behavior composed of many factors, and this study provides a view of the feeding status of only seven grasshopper species in a particular habitat and environment under natural conditions, rather than demonstrating intrinsic differences in the plant-food preference of species. Therefore, future studies should examine the feeding of grasshoppers in different habitats and at different altitudes and latitudes in order to analyze intrinsic feeding patterns of host-plant use of grasshoppers. To accurately characterize the diet of Orthoptera, a large number of individuals and interspecies must be analyzed, and it is necessary to pay attention to the obvious differences in plant consumption between males and females.
Potential intraspecific and interspecific competition.—Two grasshopper species that come from the same locations and have similar feeding tendencies may engage in intense competition (
LZ and JLR designed the experiments. WJK and KXL performed the experiments. WJK and JLR analyzed the data. JXL and XJ provided technical and material support. LZ, JLR, and WJK wrote the manuscript. All authors reviewed and considered the manuscript.
The authors declare no competing financial interests.
This research was supported by the Special Fund for Grassland Ecological Restoration Project in Bortala Mongol Autonomous Prefecture, P.R. China, and National Science and Technology Basic Resources Survey (2019FY100403).