Where does grasshopper come from river
These all-singing, all-dancing creatures truly are the gymnasts of the insect world, being able to leap distances of up to 20 times the length of their own body!
Grasshoppers have powerful, enlarged hind legs, which they use to catapult themselves out of harm’s way if they feel threatened.
There are thought to be around 30 different species of grasshopper currently breeding in the UK, although they are often confused with crickets and locusts due to their similar appearance.
Grasshoppers can be distinguished mainly by their short antennae and the fact that they tend to be solitary creatures, only coming together to mate.
Grasshoppers live in fields, long grasses, and anywhere there is a good source of food. They don’t build nests or any form of abode and are fairly nomadic, sometimes going on long journeys to find food.
Their main predators are birds, beetles, mice, snakes, and spiders, and they are also prone to attack from a type of parasitic fly. These flies lay their eggs near, or even on top of, grasshoppers and when they hatch the newborn flies eat the grasshoppers and any eggs they may have.
Perhaps one of the most musical insects around, the grasshopper can make an extraordinarily loud chirping sound, known as ‘stridulating’. They make this sound by rubbing a row of pegs that they have on their back legs against their forewings. Stridulating is used mainly by males in courtship displays to attract a mate, or to compete with rivals.
When the female has mated she will lay eggs in dry soil, and what are called ‘nymphs’ will emerge during spring when the weather starts to get warmer. From there the grasshopper will simply grow into an adult, shedding its layers until it reaches full size in August.
Appearance: Usually green, brown or grey in colour, although some are brightly coloured to warn off predators.
Size: They vary in length depending on their species, but most in the UK measure 20 – 30mm.
Lifespan: Around one year.
Diet: They feed on grass, leaves, corn and other cereal crops.
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Last date edited: 24 January 2019
Laura Ingalls Wilder and One of The Greatest Natural Disasters in American History
When a Trillion Locusts Ate Everything in Sight
In the fall of 1873, Charles and Caroline Ingalls sold their little house in the Big Woods of Wisconsin, the log cabin where their two oldest daughters had been born, for a thousand dollars. Perhaps they were struggling to pay back debts; perhaps it was simply an offer too good to refuse. Years later, Laura Ingalls Wilder would attribute the decision to the disappearance of game and her father’s distaste for the crowds piling into Wisconsin, where the population had swelled to more than a million. Charles Ingalls never seemed to realize that his ambition for a profitable farm was irreconcilable with a love of untrammeled and unpopulated wilderness. Whatever the motivation, selling a comfortable, established home with plowed fields and a productive garden was a leap into the unknown. It would be repaid with disaster and heartbreak.
In February 1874, the Ingallses headed west in their wagon across the frozen Mississippi River into Minnesota. Charles found a property on Plum Creek, a tributary of the Cottonwood River, and in June he filed a claim on 172 acres. To get title to the land, he would have to stay at least six months, establish a residence, and eventually pay $2.50 an acre—twice the price for ordinary public land, because this property was near the railroad. The land was two miles north of a not-yet-incorporated town, then known as Walnut Station, and later renamed Walnut Grove for its black walnut trees.
The family moved into a dugout already on the property, a cavity scooped out of the creek’s banks. As was customary, the roof had been crafted from a lattice of willow branches with strips of sod laid across the top. As the grass grew together, its thatch formed a relatively sturdy ceiling, but one that could be pierced by an errant ox wandering across the top.
However primitive the accommodations, Plum Creek was a beautiful place. Along the creek bed, clear water meandered over a soft, silty bottom shaded by willows and plum thickets, perfect for wading. Tall-grass prairie spread to the horizon, waving with big bluestem and a riot of summer wildflowers: bergamot, butterfly weed, coreopsis, purple coneflower, black-eyed Susan. Butterflies, meadowlarks, and red-winged blackbirds flew among the grasses while badgers lay in their burrows. Beyond the east bank lay a vast flat tableland, the vista topped by a spectacular blue sky studded with distant white.
Laura and Mary were delighted with dugout living and had “wonderful times” playing in Plum Creek. They were proud of their new responsibilities: minding three-year-old Carrie to make sure she didn’t fall in the water and watching for the family cow, brought back each afternoon by a herd boy after a day grazing on the prairie. Their father was busy plowing and digging a well next to the site where he planned to build a house. Charles Ingalls was once again chasing a wheat crop that, he hoped, would put him in the black. Wheat was selling high at the moment, $1.02 a bushel.
But even as the Ingallses were finding a place for themselves in Walnut Grove, there was trouble on the horizon. Ominously, two other men had previously filed claims on the same land, then relinquished it. Neither one had “proved up” by completing the process and paying for the claim. Whether Charles knew it or not, the previous owners may have had good reason to leave the bucolic Plum Creek property.
In June 1873, a year before the Ingallses arrived, a mystifying cloud had darkened the clear sky of southwest Minnesota on “one of the finest days of the year.” Like a demonic visitation, it was flickering red, with silver edges, and appeared to be alive, arriving “at racehorse speed.” Settlers were terrified to realize that it was composed of locusts, swarming grasshoppers that settled a foot thick over farms, breaking trees and shrubs under their weight. They sounded, according to one unnerved observer, like “thousands of scissors cutting and snipping.” A young Minnesota boy was in school with his brother when they heard the locusts coming, around two o’clock in the afternoon. As they started for home, cringing under a hail of falling insects, the boys had to “hold our hands over our faces to keep them from hitting us in our eyes.”
Farmers tried everything to get rid of them, firing guns, building barricades, starting fires, clubbing them off houses. Nothing worked. According to eyewitnesses, a month after they arrived, having eaten everything green, the grasshoppers formed a column and marched off to the east.
During that one month, the locust swarms destroyed more than three million dollars’ worth of crops, including over half a million bushels of wheat. A dozen counties reported damages, including virtually all of Redwood County. Yet though it was a blow to the state’s economy, the lost crops represented only 2 percent of that year’s production. The state wrote it off as a fluke, reveling in a banner year elsewhere.
Charles Ingalls must have heard of the grasshoppers; newspaper columns were full of them. Yet when the Ingallses settled on Plum Creek in 1874, the land was cloaked in spring green. They may have believed, as others did, that the grasshoppers had moved on. In fact, the previous year’s swarm had laid their eggs before departing. While Charles Ingalls plowed his fields, grasshoppers flew and marched in columns again, leaving destitute farmers in their wake with no seed to plant the next season. As with tornadoes, however, devastation was spotty and localized, with locusts touching down like funnel clouds in one place only to leave a neighboring township untouched. Perhaps a fluke of the wind spared Laura’s family their first year.
Losses from the 1874 locust swarm were immense. Twenty-eight counties were affected, more than twice as many as in the previous year. Farmers lost a total of 4.5 million bushels of grain and potatoes, including 2.6 million bushels of wheat. Many of them suffered crop failures two years in a row, leaving them wholly without food. An elderly farmer east of Walnut Grove pleaded with Minnesota’s chief executive as if he were God himself: “Oh, most honorable governor, I hope you will help us poor old mortals.” A girl wrote to say that her family had seen all their crops destroyed by grasshoppers and were suffering from cold, “having but two quilts and two sheets in the house.”
But the governor was busy with other matters. As he saw it, the farmers’ problems were primarily a matter for the private sector. That year, the state legislature appropriated only 5,000 dollars in direct relief, with another 25,000 to buy seed grain for affected farmers. General Henry Hastings Sibley, the state’s renowned Indian killer, was brought out of retirement to coordinate charitable relief. St. Paul merchants proved generous, but need far exceeded supply.
Minnesota was far from the only state harmed by the locusts, with destitution also reported that winter in Kansas, Nebraska, Iowa, Colorado, and Dakota Territory. In Nebraska, soldiers were tasked with delivering surplus Army clothing, and found women and children surviving in a pitiable state, men having left to find work. One boy staggered into an army outpost with bare feet wrapped in cloth, saying that his mother and five siblings were at home, starving.
Melanoplus spretus, the Rocky Mountain locust, was a stupendous force of nature. Individually, the grasshopper was scarcely noticeable: a dull olive green, just an inch and a half long. In the aggregate, however, it wielded immense power, as hinted at by the nomenclature. The word locust comes from the Latin phrase locus ustus, which means “burnt place.” Spretus means “despised.” Reflecting the general feeling, one of the common names for the creature was “hateful grasshopper.”
Ordinary grasshoppers never gather in immense clouds. Locusts, on the other hand, have the ability to become gregarious, form massive swarms, and fly astonishing distances. After settling, adults feed and lay eggs over a summer; their offspring hibernate during the winter and hatch out the following spring. It was these immature locusts that would march across the country, devouring foliage as they molted into adulthood. Until recent times, every inhabited continent on earth had at least one locust species. Before modern pest control, Europe was plagued by them; Africa, Asia, and Australia still are. The US had only a single species. The Rocky Mountain locust could go for years without swarming, until the perfect conditions set it off.
Perfect conditions were created by drought, which was a major problem across the West and Midwest in the 1870s. Indeed, the entire planet was gripped that decade by a severe El Niño event, which disrupted climate around the globe. It caused mass famines in China and India, triggering epidemics of disease; millions died. A study in Nature called it “the most destructive drought the world has ever known.”
In 1873, parts of Kansas had had their driest year on record. The following year, much of the Great Plains experienced a summer without rain. A Kansas woman remembered eerie, oppressive heat, broken only by a cataclysmic hailstorm. “The grasses seemed to wither and the cattle bunched up near the creek and well and no air seemed to stir the leaves on the trees,” she recalled. “All nature seemed still.” Then the clouds took on a “greenish hue” and hail fell, “devastating everything.”
Prolonged heat and aridity favored locusts by accelerating their growth and concentrating sugars in plants. Then, as drought wasted wild vegetation, the invertebrates focused their attention on the densest, highest-quality source of nutrients: crops. In 1875, locust nymphs hatched from their eggs throughout the Great Plains. Billions upon billions matured in a flash.
Given the severity of damage the previous two years, some of the Ingallses’ neighbors were simply sitting on their hands, refusing to plant until the danger had passed. Total acreage planted declined in 1875 and the following year by nearly 60 percent. But there was a great deal of misinformation. An inveterate newspaper reader, Charles Ingalls may have taken the advice of farm papers such as the one in Red Wing, Minnesota, which confidently reported in late May 1875 that “there are no grasshoppers . . . in any part of Minnesota north, south, east or west . . . the conclusion is inevitable that their eggs have been entirely destroyed.”
That year, after the arid summer the year before and the mild winter that followed, Charles Ingalls had made a considerable financial outlay, building a spacious house, probably the finest the family had yet lived in. It stood 20- by 24-feet square and 10 feet high, with a solid roof and floor, and three windows. It was the pride of the family. Laura would later call it “the wonderful house.” Charles built two stables for oxen and horses, plowing and cultivating 40 acres. He was feeling confident enough to take advantage of the Timber Culture Act, new legislation that allowed settlers to acquire 160 acres at no cost in exchange for planting a certain number of trees on that land. In early June 1875, he filed on such a “tree claim” a few miles north of his Plum Creek property, expanding his holdings. Meanwhile, he was raising a bumper crop of wheat.
Charles was gloating over the wheat as the family sat down to dinner one June day. Raising his arms, he showed them how tall it was, “with long beautiful heads and filling nicely.” Just as he pronounced it a “wonderful crop,” they heard someone calling them outside. It was their neighbor Olena Nelson, and she was screaming, “The grasshoppers are coming! The grasshoppers are coming!”
The Ingallses had no way of knowing it, but the locust swarm descending upon them was the largest in recorded human history. It would become known as “Albert’s swarm”: in Nebraska, a meteorologist named Albert Child measured its flight for ten days in June, telegraphing for further information from east and west, noting wind speed and carefully calculating the extent of the cloud of insects. He startled himself with his conclusions: the swarm appeared to be 110 miles wide, 1,800 miles long, and a quarter to a half mile in depth. The wind was blowing at 10 miles an hour, but the locusts were moving even faster, at 15. They covered 198,000 square miles, Child concluded, an area equal to the states of Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont combined. “This is utterly incredible,” he wrote, “yet how can we put it aside?” The cloud consisted of some 3.5 trillion insects.
The swarms swept from Saskatchewan to Texas, devouring everything in their path. The grasshoppers savored the sweat-stained handles of farm implements, chewed the wool off sheep, ate the leaves off trees. After flying, settling, consuming, and laying eggs, they began marching across the country, millions massing to form pontoons across creeks and rivers. Hoppers were said to “eat everything but the mortgage.” Terrified, people reached for comparisons, likening the insectile clouds to other natural disasters: snow storms, hail storms, tornadoes, even wildfires. “The noise their myriad jaws make when engaged in their work of destruction can be realized by any one who has ‘fought’ a prairie fire . . . the low crackling and rasping,” read a report from the US Entomological Commission, created by Congress to address the crisis. Even modern scientists stretch for language to convey the swarm’s ferocity, calling it a “metabolic wildfire.” It consumed roughly a quarter of the country.
Farmers ran frantically to cover tender garden plants with gunny sacks, quilts, shawls, and dresses, only to watch, stunned, as the insects chewed right through them. A Kansas woman found denuded pits hanging from her peach tree. She tried to save her garden by covering it with sacks but soon saw it was hopeless: “The hoppers regarded that as a huge joke, and enjoyed the awning . . . or if they could not get under, they ate their way through. The cabbage and lettuce disappeared the first afternoon.” She noticed the “neat way” they had of eating onions from the inside out, leaving the outer shell behind.
Grasshopper carcasses fouled wells, polluted creeks and rivers, and halted trains laboring up grades, the tracks greasy with crushed bodies. There were reports of children screaming in horror as insects alighted on them and of farmers’ wives becoming hysterical, mad with fright. A woman wearing a striped frock said insects settled on her and ate “every bit of green stripe in that dress.”
Technology was useless. Inventive farmers crafted “hopperdozers” out of sheet metal, contraptions drenched in coal tar and pulled across infested fields. These collected some pests, but their effectiveness was limited. Grasshoppers could work faster than fields could be dragged.
When the Ingallses saw the locusts coming, Wilder recalled, her father put on his hat and “went out toward his beautiful wheat field.” He set fire to berms of straw and manure piled around the field, hoping to smoke out the locusts. But it was to no avail. By noon of the second day, he gave up and returned to the house exhausted, “his eyes all swollen and red from the smoke and lack of sleep.”
The dream of the perfect crop died that day. It was a nightmarish repetition of Caroline Ingalls’s early privation, when she and her siblings had had nothing to eat but bread crumbs and water. Once again there was no money to buy food. The catastrophe could not have come at a worse time: Caroline was pregnant again, expecting a child in November.
On the third day, the insects began marching west, walking inexorably up the east side of the house, across the roof, and down the other side, coming in the window by the score until Caroline ran to close it. They were marching, Wilder wrote, “like an army,” and the family looked around at each other “as though we were just waked from a bad dream.” Grasshopper bodies filled the creek and left fields pocked with holes, “like a honey comb.” The holes were filled with eggs.
The locust plague constituted the worst and most widespread natural disaster the country had ever seen, causing an estimated $200 million in damage to western agriculture (the equivalent of $116 billion today) and threatening millions of farmers in remote locations—far from social services in the cities—with starvation. In 1875, Minnesota once again lost more than two million bushels of wheat. That January, the so-called Grasshopper Legislature appropriated a mere $20,000 in aid for the stricken, extending the deadline for property taxes but balking at doing more for those perceived as shirkers. Miserly amounts of food aid were distributed in some counties, in amounts ranging from two to four dollars per family, while the minimum required by a family of four for a year was estimated at two hundred dollars. Just like the locusts themselves, relief, such as it was, fell in haphazard fashion.
As for the federal government, Congress appropriated $100,000 in aid for settlers on the western frontier. But the easterners were generally cavalier. Newspapers shrugged at the constant reports of “famine, suffering and misery” in the West. “It is humiliating to have them so constantly before us, passing round the hat,” wrote one editorialist.
Even as Minnesota distributed aid, it expressed contempt for the destitute, enacting punitive regulations that required farmers to prove they were completely bereft before applying for relief. In a cruel and counterproductive move, the state demanded that applicants sell any livestock they owned before receiving aid. Meanwhile, trying to empty the ocean a drop at a time, counties nailed flyers to town walls advertising a bounty for grasshoppers: five cents a quart, “caught and delivered dead.” An informational pamphlet distributed by a railroad urged farmers to get busy collecting the pests, since solving the problem was their responsibility. Newspapers advised their hungry readers to eat the bugs: “make it a ‘hopper’ feast.”
In desperation, Charles Ingalls sold his horses, leaving the money with his wife. With nothing left for train fare, he walked 200 miles east to work the harvest, possibly near his brother Peter Ingalls’ farm in southeastern Minnesota, where the grasshoppers had not penetrated. When he returned, he moved the family into town for the winter, where they rented a house behind the church. On November 30, Charles signed a sworn statement before county officials stating that he was “wholy without means,” the humiliating requirement of the relief act passed earlier that year. It made him eligible to receive two half-barrels of flour, worth five dollars and twenty-five cents. He may never have told his children where the flour came from.
The one thousand dollars he had received for the little house in the Big Woods was long gone. Wilder later recalled that her parents had hoped Plum Creek would restore their fortunes. “Prosperity was only just around the corner, just till that crop of wheat was raised,” she wrote wistfully. “Plum Creek was safety and then look what happened.”
Charles Ingalls and his family must have longed for their former home. The locust swarm had never crossed the Mississippi River. It left Wisconsin untouched.
From Prairie Fires: The American Dreams of Laura Ingalls Wilder by Caroline Fraser. Courtesy Henry Holt and Co. Copyright 2017, Caroline Fraser.
Big Two-Hearted River (Parts I and II)
by Ernest Hemingway
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- The Grasshopper
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- The Grasshopper
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Symbolism, Imagery, Allegory
Do you write about every bug you see? Neither does Hemingway. That should be your first clue that the grasshopper means something more than a grasshopper. To be fair, though, this grasshopper definitely starts off as any other one—until, that is, Nick tells us:
These were just ordinary hoppers, but all a sooty black in color. Nick had wondered about them as he walked, without really thinking about them. Now, as he watched the black hopper that was nibbling at the wool of his sock with its fourway lip, he realized that they had all turned black from living in the burned-over land. He realized that the fire must have come the year before, but the grasshoppers were all black now. He wondered how long they would stay that way. (I.12)
Hm, interesting observation, don’t you think? Something has desolated the landscape and, even though it was a while ago, it still has an effect on the wildlife—maybe even a permanent one.
To put it bluntly, the metaphor here seems to be the war. “Ordinary hoppers,” i.e. ordinary people like Nick, have been affected, in some way reflecting the destruction of the landscape. And even though the destruction is over and has been for some time, he’s still manifesting its effects. And Nick has no idea if or when these effects will change.
But the episode with the grasshopper isn’t hopeless; after all, Nick tells the grasshopper to “Fly away somewhere” (I.14). The message here seems to be that life goes on. Sure, the grasshoppers are black, and they might be for a while, but that doesn’t stop them from being grasshoppers. In other words, if there is a way for the grasshopper to be free, then there is a way for Nick too.
Hemingway seems to be saying something about the way people wear their traumatic experiences. The grasshoppers literally “wear” what has happened to them by being the black color of soot. Nick doesn’t literally wear his experiences—as far as we can tell, he isn’t physically maimed—but he is carrying something that he can’t really speak about (many people still viewed shell shock and combat stress as a weakness that manly men needed to just “get over”). So he’s dealing with this thing that no one really wants to acknowledge. Therefore, we can’t see Nick’s trauma as clearly as we can the grasshoppers’, but that doesn’t mean it isn’t there.
Where does grasshopper come from river
ECOLOGY, BEHAVIOR AND BIONOMICS
Feeding patterns of the aquatic grasshopper Cornops aquaticum (Bruner) (Orthoptera: Acrididae) in the middle Paraná river, Argentina
S Capello I ; ML de Wysiecki II ; M Marchese I, III
I Instituto Nacional de Limnología (INALI-CONICET-UNL), Santa Fe, Argentina
II Centro de Estudios Parasitológicos y de Vectores (CEPAVE) (CCT-La Plata- CONICET- UNLP), La Plata, Argentina
III Facultad de Humanidades y Ciencias-UNL, Santa Fe, Argentina
The aquatic grasshopper Cornops aquaticum (Bruner) is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay. This grasshopper is host-specific to aquatic plants of the genera Eichhornia and Pontederia. The objectives of this study were to analyze the feeding patterns of the aquatic grasshopper C. aquaticum in relationship to development stages and sex and to determine the food consumption rate in their host plant, Eichhornia crassipes. Samples were collected from April 2006 to May 2007 in different floodplain lakes of the Middle Parana River. The average consumption was greater in the females (0.127 g food/day ± 0.051) than in the males (0.060 g food/day ± 0.025). The feces of 361 nymphs and adults of this locust were examined and the most common tissue fragments found were of the water hyacinth (E. crassipes). In the initial nymphal stages (I, II and III), an exclusive consumption of E. crassipes was registered, while in the IV and V stages the choice included also other macrophytes. In summary, C. aquaticum presents polyphagy in the field, feeding on six macrophytes of different classes and families.
Keywords: Diet composition, dairy consumption rate, nutritional index
The diet breadth of grasshoppers varies from strict monophagy to extreme polyphagy. Between these extremes there are species exhibiting varying degrees of selectivity of the food they eat. The essential difference among polyphagous, oligophagous and monophagous species is one of sensitivity to deterrents (Bernays & Chapman 1994). Isely (1944) showed that grasshoppers are conveniently classified as grass-feeders (graminivorous), forb-feeders (forbivorous), or a mix of the two (ambivorous or mixed feeders). Joern (1986) pointed out that the most oligophagous species are grass feeders, while monophagous- and polyphagous species are forb-feeders. Forbs are generally considered a higher quality food than grasses for most herbivores because of their higher nitrogen, phosphorus and sugar contents (Randolph et al 1995).
The feeding patterns of nymphs and adults of a given species of grasshopper are similar, and vary according to seasonal changes in the availability and quality of food (Gangwere 1961), and the processes of learning (Bernays & Bright 1991). The aquatic grasshopper Cornops aquaticum (Bruner) is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay (Adis et al 2007). It is host-specific to aquatic plants of the genera Eichhornia (Pontederiaceae) and Pontederia (Pontederiaceae) (Adis & Victoria 2001, Adis & Junk 2003). Gangwere & Ronderos (1975) suggested that the high degree of specificity of this grasshopper depends on the mandible type and it is classified as parenchyma-forbivorous because this acrids eats the parenchyma of plants with wide leaves.
Very little is known concerning the Orthoptera species that inhabit moist or wet environments because usually such species do not become pests. Nevertheless, C. aquaticum could have potential use for biological control of the water hyacinth, Eichhornia crassipes weed, and is planned to be released in South Africa for this purpose (Oberholzer & Hill 2001). This macrophyte is considered the world’s most important aquatic weed (Center 1994, Wright & Purcell 1995) because it invades aquatic ecosystems on almost every continent, reproducing rapidly, dispersing easily, displacing indigenous floras, and causing problems in reservoirs, fisheries, irrigation schemes, and transportation routes (Timmer & Weldon 1967, Mitchell & Thomas 1972, Gopal 1987, Ogwang & Molo 2004).
The objectives of this study were to analyze the feeding patterns of the aquatic grasshopper C. aquaticum in relationship to development stages and sex and to determine the food consumption rate in their host plant, E. crassipes.
Material and Methods
Samples were collected from April 2006 to May 2007 in different floodplain lakes of the Middle Paraná River. The selected sites differed in their degree of connectivity with the main channel, being lakes either connected permanently (31°38′ 43.77″ S; 60°34′ 35.07″ O), or temporarily to the Paraná River (31°40′ 14.40″ S; 60°34′ 44.43″ O).
The vegetation of these lakes is associated directly with the hydrological regime of the Paraná River, because the species richness varies according to the level of water (Sabattini & Lallana 2007). In spite of the differences in connectivity of the lakes, in both sites the most important macrophytes were the same: E. crassipes, Paspalum repens, Salvinia herzogii, Pistia stratiotes, Ludwigia peploides, Echinochloa sp. and Polygonum sp.
Cornops aquaticum adult grasshoppers were collected with entomological nets in the spring (November) of 2007. Thirty grasshoppers of each sex were transported to the laboratory to determine their consumption rate of the host plant E. crassipes. After 2h of fasting, the grasshoppers were weighed and placed individually in vials with E. crassipes leaves. After 24h, the grasshoppers, the food remaining and the feces were oven-dried (at 60ºC for 72h or constant mass) and weighed in an OHAUS balance (accuracy of 10 -5 g).
The biomass gained and the food consumed were calculated from the difference between the initial and the final dry weights. The initial dry weight of the grasshoppers and the leaves were derived from the fresh weight and a conversion factor, which was obtained by dividing the product of the dry weight/fresh weight of 10 grasshoppers of each sex and 50 leaves of water hyacinth with the same characteristics of those used in the experiments (Pereyra 1995).
The consumption rate, growth and feeding efficiency were calculated using the following nutritional indexes (Pereyra et al 1996): i) rate of relative consumption: ingested food/mean dry weight of individual/day, ii) rate of relative growth: biomass gained/mean dry weight of individual/day, and iii) efficiency of ingested food conversion: (gained biomass/ingested food) x 100.
The diet composition of C. aquaticum was determined by microanalysis of the feces under an optical microscope (400x) according to Arriaga (1981, 1986). Individuals (152 nymphs and 209 adults) were sampled fortnightly with an entomological net from 2006-2007. Each individual collected was immediately placed in a paper tube for a period of 24h and the feces collected, clarified with 10% potassium hydroxide (KOH) and mounted on a slide. Twenty microscope fields were randomly selected for each sample (feces of one individual) where at least one epidermic tissue piece was present (Sheldon & Roger 1978).
The anatomy of leaves of all the macrophytes recorded in the floodplain lakes was previously analyzed. The epidermal tissues were identified based on cellular characteristics (epidermal cells, stomata, trichomes or hairs, etc) and photographs were taken under the optical microscope. The vegetal tissues observed in the feces of C. aquaticum were compared with these reference collections to identify the plant species consumed.
Frequency of occurrence was calculated for each food item present based on the number of fields containing this particular food item.
The data collected were grouped among four seasons (autumn, winter, spring and summer) to conduct statistical analyses. Factorial design (2 k ) was used to test differences in feeding rates between development stages and sex. The individuals that consumed water hyacinth exclusively were excluded in this test. The level of probability that was considered significant was P
The daily consumption was higher for females (0.127 g food/day ± 0.051) than for males (0.060 g food/day ± 0.025). An average consumption of 0.093 g food/day was noted for adults of both sexes.
The female adults presented high values in all nutritional indexes in comparison with the male adults. The relative consumption rate average, relative growth rate and ingested food conversion efficiency obtained for C. aquaticum are shown in Table 1.
The feces of 361 grasshoppers were examined (152 nymphs and 209 adults), and plant tissues of six species were identified. The most common tissue fragments found in the feces were of the water hyacinth, representing 90.4% of all samples. Others plant species consumed were P. repens (3.6%), L. peploides (3.6%), Panicum sp., Polygonum sp. and one unidentified grass (2.4%). The epidermal structures (epidermal cells, stomas, trichomes or hairs) of the three most consumed plants are shown in Fig 1.
A total of 298 individuals consumed exclusively E. crassipes, 52 individuals, E. crassipes and other plants and 11 non-E. crassipes host plants.
In the initial nymphal stages (I, II and III, n = 51), only E. crassipes was consumed, while in the stages IV and V (n = 86) other macrophytes were also consumed (mainly L. peplo >
The amplitude of diet of C. aquaticum is different according to the development state, being the adult females those that present greater niche breadth, consuming the six plants registered in feces (Fig 2)
There were no significant differences between the botanical composition and the stages of development (P = 0.955) and sex (P = 0.251) of C. aquaticum, demonstrating that the election of the nutritional items depends neither on the stage of development nor on the sex of the grasshoppers (Table 2).
The daily consumption by individual in C. aquaticum was greater in females than in males. Similar results available when the daily consumption of aquatic (Amorim & Adis 1994) and terrestrial grasshoppers were evaluated (Gangwere 1959, de Wysiecki 1986, Sánchez & de Wysiecki 1990, Mariottini 2009). In coincidence with Lockwood et al (1996), females consume greater amounts of food than males because they have higher protein demands for egg production.
When E. crassipes was the host plant, the relative consumption rate of C. aquaticum populations of the Central Amazonia was 0.9 g food/g individual/day, and the individual consumption per day was 0.0522 g in males and 0.0837 g in females (Adis & Junk 2003), recording slightly higher values than in our study. Amorim & Adis (1994) reported a lower relative consumption rate of adult males (0.135 g food/g individual/day) and adult females (0.229 g food/g individual/day) of the semiaquatic grasshopper Stenacris fissicauda fissicauda (Bruner) compared to that of C. aquaticum. Thus, the consumption capacity of C. aquaticum was greater when considering that the dry weight of C. aquaticum is greater than that of S. fissicauda fissicauda.
Comparing the relative consumption rate obtained, the aquatic grasshopper C. aquaticum consumes a larger amount of food than the terrestrial S. fissicauda fissicauda and Dichroplus pratensis Bruner (Pereyra et al 1996). By coincidence, Cyr & Pace (1993) reported that aquatic herbivores consumed greater quantities of biomass than their terrestrial counterparts.
The efficiency of C. aquaticum to convert the ingested food was higher in females than in males, concurring with the results obtained by Sánchez & de Wysiecki (1990) and de Wysiecki & Sánchez (1992) for D. pratensis.
Early instars (I, II and III) of C. aquaticum consumed water hyacinth leaves exclusively. This finding agrees with that reported by Sword & Dopman (1999) for Schistocerca lineate (Scudder), which represent a more extreme situation in which the early stages are monophagous. However, the later instars and adults become polyphagous. The greater variety of mixed foregut contents in later instars might also suggest their greater mobility (Bernays & Chapman 1994). In contrast, early instars of Chorthippus parallelus (Zetterstedt) were observed to feed frequently on three or four of the grass species, suggesting that they require a wider range of grass species (Bernays & Bright 2001).
Bennett (1971, 1974) and Carbonell (1981) demonstrated that C. aquaticum could eat another variety of aquatic plant (Commelina sp.), but their life cycle is associated with Eichhornia because other vegetal species were unsuitable for their endophytic oviposition.
In an experimental study on feeding habits of C. aquaticum, the acceptance of six aquatic macrophytes species was detected, indicating that these plants can represent alternative resources, but are not essential for the development of the species (Vieira & dos Santos 2003). Ludwigia sp. and P. repens are the only plants found in this study, what confirms that the feeding pattern of an herbivore insect in its natural environment would differ from the laboratory conditions, as suggested elsewhere (Bernays & Lewis 1986, Bernays & Simpson 1990, Bernays & Chapman 1994).
The specificity of C. aquaticum on E. crassipes has been determined for populations of the Pantanal wetlands in Brazil (Lhano et al 2005), but those in South Africa also feed on cultivated plants such as Canna indica and Musa paradisiaca (Oberholzer & Hill 2001).
An important preference for monocotyledonous plants (approximately 95%) was observed in the diet composition of C. aquaticum through the whole year in contrast to that revealed by Chapman (1990) that the polyphagous herbivores consume greater proportions of dicotyledons.
In summary, C. aquaticum presents polyphagy in the field, feeding on six different species of macrophytes of various classes and families (monocotyledonous: Pontederiaceae and Poaceae; dicotyledonous: Onagraceae and Polygonaceae). Although C. aquaticum is considered specific to the genus Eichhornia, this grasshopper also feeds on other plant species in the laboratory and in the field. Its acceptance of several plant species in the absence of the preferred host plant could indicate that it is the host plant’s relative abundance in the field that determines the C. aquaticum diet breadth.
The authors dedicate this work in memory to Dr Joachim Adis. We thank to Language Edit by the revision of our manuscript and especially thanks to the Department of Mathematical of the Faculty of Biochemistry and Biological Science (FBCB – UNL) for help in data analysis. This study was financed in part by a Grant of Orthopterist´s Society and CONICET.
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Instituto Nacional de Limnología
Ciudad Universitaria, 3000
Santa Fe, Argentina
Received 10 December 2009 and accepted 27 August 2010
Edited by Angelo Pallini – UFV
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