Unexpected faunistic records of Rhacocleis annulata, Eyprepocnemis plorans, and Xya pfaendleri (Orthoptera) from Croatia and Slovenia

Interesting records of one bush-cricket and two grasshopper species are reported from Croatia and Slovenia. Rhacocleis annulata Fieber, 1853 (Tettigoniidae: Tettigoniinae) has been reported for the first time from Croatia (Dubrava by Šibenik), as well as for Slovenia (Borovnica SW of Ljubljana); Eyprepocnemis plorans (Charpentier, 1825) (Acrididae: Eyprepocnemidinae) is reported for the first time for Croatia, also from Dubrava; and finally, the Xya pfaendleri Harz, 1970 (Tridactylidae: Tridactylinae) record from Dubrava represents the first record of this species from Dalmatia. Rhacocleis annulata and Eyprepocnemis plorans are known to be spreading through Europe, so these records contribute to the understanding of their dispersal in Southern Europe. Croatian Orthopteran fauna now counts, with two species added, 187 species, while Slovenian Orthopteran fauna now counts, with one species added, 158 species.

Analysis of the management of grasshopper species (Orthoptera: Acrididae), agricultural pest in Laprida county, Buenos Aires, Argentina

Grasshoppers are among the dominant insects in most grassland systems. These insects’ communities tend to exhibit temporal variations in the distribution and abundance of their species, and during outbreak years cause important economic loss in both implanted pastures and crops. In the study area, Laprida county, as well as in other areas of Buenos Aires province, this pest problem has been recognized since last century. The aim of this study was to analyze the pest management of grasshoppers made by farmers and related institutions in Laprida using both qualitative (interviews and documentary observation) and quantitative methods (surveys). About 80% of surveyed farmers considered that grasshoppers are the main pest in the region, and 60% of them apply chemical insecticides against this pest, mainly on crops. Besides, only 12.8% of surveyed farmers are aware of nonchemical alternatives for pest control, such us biological control and natural enemies. Most of the interviewed farmers acknowledged the importance of preventive management through systematic grasshopper monitoring and spot treatments in risky areas. Additionally, farmers showed interest in the implementation of more environmentally-safer strategies such as biological control.

Taxonomical clarification of Tetrix gibberosa (Wang & Zheng), a high-backed pygmy grasshopper species from eastern PR China (Orthoptera: Tetrigidae)

Tetrix gibberosa (Wang & Zheng) is a high-backed pygmy grasshopper species from eastern PR China. Due to its reduced hind wings and pleomorphism (length changes of hind wings and the hind pronotal process, which is generally called macropterous and brachypterous morphs), the species have been described into different species which involve several taxonomically confused genera. This study clarifies its taxonomy and distribution and provides ecological information for the species. At the same time, we comment the relationships of related genera in the subfamily Tetriginae, including Tetrix Latreille, Exothotettix Zheng & Jiang, Alulatettix Liang, Aalatettix Zheng & Mao, Formosatettix Tinkham, and Formosatettixoides Zheng. Additionally, we report for the first time that nematodes can parasitize pygmy grasshoppers. New synonyms are proposed: Tetrix gibberosa (Wang & Zheng, 1993) = Alulatettix bulbosus Zheng & Zhong, 2001, syn. nov., = Exothotettix jiangxiensis Liang & Jia, 2008, syn. nov., = Tetrix glochinota Zhao, Niu & Zheng, 2010, syn. nov., = Alulatettix nigromarginalis Zhang, Deng & Zha, 2014, syn. nov., = Alulatettix flavotibialis Zhang, Deng & Zha, 2014, syn. nov..

Establishing the nutritional landscape and macronutrient preferences of a major United States rangeland pest, Melanoplus sanguinipes, in field and lab populations

When given a choice, most animals will self-select an optimal blend of nutrients that maximizes growth and reproduction (termed “intake target” or IT). For example, several grasshopper and locust species select a carbohydrate-biased IT, consuming up to double the amount of carbohydrate relative to protein, thereby increasing growth, survival, and migratory capacity. ITs are not static, and there is some evidence they can change through ontogeny, with activity, and in response to environmental factors. However, little research has investigated how these factors influence the relative need for different nutrients and how subsequent shifts in ITs affect the capacity of animals to acquire an optimal diet in nature. In this study, we determined the ITs of 5th instar (final juvenile stage) Melanoplus sanguinipes (Fabricius, 1798), a prevalent crop and rangeland grasshopper pest in the United States, using two wild populations and one lab colony. We simultaneously collected host plants to determine the nutritional landscapes available to the wild populations and measured the performance of the lab colony on restricted diets. Overall, we found that the diet of the wild populations was more carbohydrate-biased than their lab counterparts, as has been found in other grasshopper species, and that their ITs closely matched their nutritional landscape. However, we also found that M. sanguinipes had the lowest performance metrics when feeding on the highest carbohydrate diets, whereas more balanced diets or protein-rich diets had higher performance metrics. This research may open avenues for studying how management strategies coincide with nutritional physiology to develop low-dose treatments specific to the nutritional landscape for the pest of interest.

Embryonic Development of Grasshopper Populations Along Latitudinal Gradients Reveal Differential Thermoaccumulation for Adaptation to Climate Warming

Climate warming has a remarkable effect on the distribution, phenology, and development of insects. Although the embryonic development and phenology of non-diapause grasshopper species are more susceptible to warming than those of diapause species, the responses of developmental traits in conspecifically different populations to climate warming remain unknown. Here, we compared the mtDNA sequences and embryonic development of eight populations of grasshopper species (Chorthippus dubius) in field-based manipulated warming and laboratory experiments. The mtDNA sequences showed a significant genetic differentiation of the southernmost population from the other seven populations on the Mongolian Plateau. The embryonic development of the southernmost population was significantly slower than those of the northern populations at the same incubation temperatures. Interestingly, laboratory experiments showed that a significant difference exists in the effective accumulated degree days (EADD) but not in the lower development threshold temperatures (LDTT) among the different populations. The high-latitude populations required less EADD than the low-latitude populations. The warming treatments significantly accelerated the embryonic development in the field and decreased duration from embryos to hatchlings of all eight populations in the incubation. In addition, warming treatments in field significantly increased EADD requirement per stage in the incubation. Linear regression model confirmed that the embryonic development characteristics of eight populations were correlated with the annual mean temperature and total precipitation of embryonic development duration. The results indicated that grasshopper species have evolved a strategy of adjusting their EADD but not their LDTT to adapt to temperature changes. The variations in the EADD among the different populations enabled the grasshopper eggs to buffer the influences of higher temperatures on development and preserve their univoltine nature in temperate regions while encountering warmer climatic conditions. Thus, the findings of this study is valuable for our understanding species variation and evolution, and as such has direct implication for modeling biological response to climate warming.

Identification of diverse viruses associated with grasshoppers unveils phylogenetic congruence between hosts and viruses

Locusts and grasshoppers are one of the most dangerous agricultural pests. Environmentally benign microbial pesticides are increasingly desirable for controlling locust outbreaks in fragile ecosystems. Here we use metagenomic sequencing to profile the rich viral communities in 34 grasshopper species and report 322 viruses, including 202 novel species. Most of the identified viruses are related to other insect viruses and some are targeted by antiviral RNAi pathway, indicating they infect grasshoppers. Some plant/fungi/vertebrate associated viruses are also abundant in our samples. Our analysis of relationships between host and virus phylogenies suggests that the composition of viromes is closely allied with host evolution, and there is significant phylogenetic relatedness between grasshoppers and viruses from Lispiviridae, Partitiviridae, Orthomyxoviridae, Virgaviridae and Flaviviridae. Overall, this study is a thorough exploration of viruses in grasshoppers and provide an essential evolutionary and ecological context for host-virus interaction in Acridoidea.

Phenological Asynchrony Is Associated With Diapause Program and Heat Shock Protein Expression in Three Grasshopper Species in the Inner Mongolian Steppe

Phenological asynchrony is a common and important natural phenomenon that affects interspecific interaction, resource allocation, species survival, and range shift in sympatric species. However, the underpinnings for regulating phenological asynchrony at physiological and molecular levels remains less explored. We investigated the seasonal pattern of emergence period and abundance in three dominant grasshopper species, namely, Dasyhipus barbipes, Oedalus asiaticus, and Chorthippus dubius, which occur sympatrically in the Inner Mongolian steppe. The three grasshopper species decoupled their population occurrence phenology that occurred in a growing season between May and September and diverged into early, middle, and late seasonal species. We also examined the association of embryonic diapause and heat shock protein (Hsp) expression with phenological asynchrony in the three species. The species developed different embryonic diapause programs, i.e., obligate diapause, facultative diapause, and non-diapause, to control the timing of egg hatching and seasonality of population occurrence. The diapausing eggs exhibited significantly enhanced supercooling capacity compared with pre- and post-diapausing eggs. Gene expression analysis in the developmental process revealed that three Hsps, e.g., Hsp20.6, Hsp40, and Hsp90, were significantly upregulated in diapause state relative to that in pre- and post-diapause states; expression of these genes seems to be associated with the diapause program regulation. This study provides a possible mechanistic explanation for phenological differentiation among sympatric species in a typical steppe habitat and establishes a potential linkage among phenological asynchrony, diapause, and Hsp gene expression. The findings will facilitate our prediction of population dynamics and pest management.

Phenology dictates the import of climate change on geographic distributions of six co-occurring North American grasshoppers

Throughout the last century, climate change has altered the geographic distributions of many species. Insects, in particular, vary in their ability to track changing climates, and it is likely that phenology is an important determinant of how well expands can either expand or shift their geographic distributions in response to climate change. Grasshoppers are an ideal group to test this hypothesis, given that co-occurring confamilial, and even congeneric, species can differ in phenology. Here, I tested the hypothesis that early- and late-season species should possess different range expansion potentials, as estimated by habitat suitability from ecological niche models. I used nine different modeling techniques to estimate habitat suitability of six grasshopper species of varying phenology under two climate scenarios for the year 2050. My results support the hypothesis that phenology is an important determinant of range expansion potential. Early-season species might shift northward during the spring, while the modeled geographic distributions of late-season species were generally constant under climate change, likely because they were pre-adapted to hot and dry conditions. Phenology might therefore be a good predictor of how insect distributions might change in the future, and conservation efforts might focus most heavily on early-season species that are most impacted by climate change.

The genomic architecture of inversion clines in a grasshopper species group with a complex biogeographic history

Chromosomal inversions play a role in the adaptation and diversification of different systems, mainly due to supergenes resulting from recombination suppression. Supergenes are “clusters” of genes in linkage disequilibrium (LD) whose frequencies may be associated with environmental variables. The grasshopper “species complex” Trimerotropis pallidipennis is considered to have several genetic lineages distributed from North to South America in arid and semi-arid high-altitude environments. The southernmost lineage, Trimerotropis sp., bears 4 to 7 putative inversion polymorphisms with clinal variation, possibly allowing adaptation to temperate environments. We analyzed chromosomal, mitochondrial and genome-wide SNP markers in 19 Trimerotropis sp. populations mainly distributed along two altitudinal gradients (MS and Ju). We show that populations across Argentina are formed by two main chromosomally and genetically differentiated lineages: one distributed in the southernmost border of the “Andes Centrales”, adding evidence for a differentiation hotspot in this area; and the other widely distributed in Argentina. Within the latter, genomic architecture analysis revealed four clusters of loci in high LD that correspond to inversions, of which at least one is associated to a chromosomal rearrangement, confirming its status as “true inversion”. We demonstrated the stability of chromosome polymorphisms for more than 20 generations and the occurrence of non-neutral markers associated with inversions and environmental variables. Inversion clines could be the consequence of coupling between extrinsic postzygotic barriers, leading to a hybrid zone, and spatially varying selection along environmental gradients. These results provide a framework for future investigations about candidate genes implicated in the rapid adaptation to new environments.