Evaluation of Methods for Screening Grasses for Resistance to Feeding

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G. B. HEWITT AND C. C. BLICKENSTAFF

Highlight: A study was initiated to find a rapid method of screening forage (1949) studied the feasibility of using plant selections for grasshopper preference. Six grass species both as seedlings crested wheatgrass for regressing field and as plants 6 weeks older were fed to nymphs and/or adults of five grasshopper margins in order to crowd out weeds species and one group of nymphs of mixed species. It was concluded that it is which are attractive as food for certain feasible to screen plant species in the seedling stage for preference by usinggrass- grasshopper species. Putnam (1962) hopper nymphs because the nymphs selected plant species of both ages equally reported on both native and intro- well and their preferences were similar to those of adults. This allows for more rapid screening of plants than would be the case with older plants and adult duced plants as food for Camnula . pellucida (Scudder) in western Canada. In Arizona, Nerney and Hamilton, resistance in crop plants has forage production, erosion control, (1967) mention that the grasshopper been most valuable in reducing damage and improvement of soil water-holding MorseieZZa f7aviven tris (Bruner) des- by various insect pests. This method of capacity (Gomm, 1962; Parker, 1961; troyed 85 to 90% of the seed crop of control might also be used as a means and Rauzi et al., 1963). During 1966, reseeded lovegrass and sideoats grama. of reducing damage by rangeland grass- approximately 9.8 million dollars was Hewitt (1968, 1969) reported on the hoppers. For this purpose a rapid involved in four types of range im- resistance of 26 forage plants to feed- method of screening forage plants for provement practices on the public ing by MeZanopZus sanguinipes (F.). In grasshopper feeding preferences is lands in 11 western states by four Kansas, Chu and Knutson (1970) desirable. As increased emphasis is federal agencies. Approximately 2.1 studied the food preferences of eight placed on range rehabilitation any million of this total was used in grasshopper species for 11 species of information on methods for screening seeding programs (Public Land Law cultivated grasses. They determined forage plants for grasshopper feeding Review Commission, 1970). the type of damage (preference for preferences will be of assistance to A number of workers have deter- leaves, inflorescence, seeds, etc.) plant breeders and range management mined the native preferred food plants caused by both nymphs and adults of personnel. f o r m any rangeland grasshopper the eight species. For example, in recent years, species based on crop analysis and reseeding and interseeding rangeland observations (Isely, 1938; Anderson A study was therefore initiated to has often proved profitable in terms of and Wright, 1952; Brooks, 1958; find a rapid means of screening plant Lambley, 1967; Ueckert, 1968; selections for resistance to grasshopper Mulkern et al., 1969; Hansen and feeding. One objective was to deter- The authors are research entomologist, Ueckert, 1970; and Ueckert et al., mine which stage of grasshopper Agricultural Research Service, U.S. Depart- ment of Agriculture. Research reported here 1972). However, studies on forage development (nymph or adult) and was conducted at the U.S. Dep. Agr. Grass- varieties and species used in reseeding which of two stages of plant develop- hopper Laboratory, Montana State Univer- sity, Bozeman. The junior author is current- programs and whether or not they are ment (seedlings or more mature ly located at the U.S. Dep. Agr. Entomology preferred by grasshoppers are limited. plants) gives the best indication of Laboratory, Twin Falls, Idaho. Herman and Eslick (1939) reported on resistance. A second objective was to The authors greatly appreciate the inter- est and assistance of Stephen R. Chapman, the selection of food plants by grass- check the possibility that one or two Plant and Soil Science Department, Mon- hoppers in a grass field nursery in grasshopper species might be represent- tana State University, Bozeman. The statis- Pullman, Washington. They found the ative in their preferences of other tical computations were performed by Gary Richardson, ARS Statistical Laboratory, Standard variety of crested wheatgrass species with similar food habits, since Fort Collins, Colorado. Wayne Burleson, Grasshopper Laboratory, assisted with field (Agropyron cristatum (L.) Gaertn.) most economically important species and greenhouse work. was damaged considerably more than are graminivorous. Reported here are Manuscript received August 4, 1973. the Fairway variety. Also, Davis, the interactions of nine grasshopper

JOURNAL OF RANGE MANAGEMENT 27(4), July 1974 285 Table 1. Relative percentage eaten of six grass species at two phenological stages by nine different groups of grasshoppers.

Mean Grasshopper Grass’ Plant growth deviation stage Species Stage2 Stvi Elju Agtr Agda Dagl Brin from avg Seedling plants A. deorum 2.5 10.0 10.5 28.0 21.8 28.0 1.8 M. sanguinipes 4.5 14.8 14.0 28.8 19.8 18.5 3.1 Mixed 6.8 11.0 17.5 28.0 14.8 22.0 3.6 C. pellucida 9.0 14.5 13.5 31.5 20.5 11.2 5.2 A. deorum 3.5 13.0 22.2 31.8 15.0 15.2 6.2 B. brunnea 4.0 5.2 6.5 16.2 30.2 37.8 6.8 M. sanguinipes 3.5 12.0 23.8 34.8 6.5 18.8 7.6 M. pardalinus 4.5 2.0 9.8 12.2 25.2 46.0 8.0 C. pellucida 1.5 1.8 5.0 15.8 37.0 39.5 9.6 Avg seedlings3 4.4 a 9.4 ab 13.6 b 25.2 d 21.2 cd 26.3 d Advanced plants C. pellucida 2.8 11.0 20.2 15.5 23.0 27.8 2.2 Mixed 1.8 8.2 17.5 10.5 31.2 30.8 3.6 B. brunnea 4.0 1.5 25.2 14.5 36.8 18.0 4.5 A. deorum 3.2 6.2 25.5 21.5 27.2 15.8 5.2 M. sanguinipes .5 8.2 15.8 7.8 30.8 37.0 5.7 A. deorum 3.5 2.0 12.0 20.8 37.2 25.0 5.8 M. sanguinipes 3.2 12.8 16.0 12.8 16.5 38.8 6.3 M. pardalinus 8.0 3.2 30.5 22.2 15.0 21.0 6.6 C. pellucida 1.0 2.2 46.8 6.8 17.5 26.0 7.8 Avg advanced 3 3.1 a 6.2 a 23.3 d 14.7 bc 26.1 d 26.7 d

Avg seedlings and advanced 3.8 7.8 18.5 20.0 23.7 26.5 ’ Stvi = green needlegrass; Elju = Russian wildrye; Agtr = pubescent wheatgrass; Agda = thickspike wheatgrass; Dagl = orchardgrass; Brin = smooth brome. 2A = adults; N = nymphs. 3Means, both amo n g and between plant ages, accompanied by the same letter do not differ significantly at the 1% level.

groups and six grass species. used. Before a test, the plantings were 300/cage and depended on the devel- thinned to insure that both the test opmental stage of the grass, the size of Materials and Methods and control portions of a row con- the grasshoppers, and the number of The six grass species used were tained comparable amounts of foliage. grasshoppers available. More grass- selected to represent the range of When the second planting was in hoppers were used on plantings that preference by and resistance to M. the 2-leaf stage and the first planting had the most vegetative growth. The consisted of more advanced vegetative grasshoppers were allowed to feed sanguinipes observed in previous studies (Hewitt, 1968, 1969) and were growth, the cages were infested with from 24 to 96 hours, depending on nine groups of rangeland grasshoppers, how rapidly they consumed the grow- as follows: green needlegrass (Stipa all of which could be found on short- ing plants, and were removed as soon viridula Trin.), thickspike wheatgrass grass rangeland in the same habitat: as an observable range of damage was (Agropyron dasystachyum (Hook.) ( 1) nymphs and (2) adults of M. apparent among the six species of grass S cribn.), smooth brome (Bromus nymphs and (4) adults but before any one grass species was inermis Leyss), pubescent wheatgrass sanguinipes; (3) of (Scudder); completely eaten, All testing was done (Agropyron trichophorum (Link) Ageneotettix deorum and (5) nymphs and (6) adults of in a greenhouse. Richt.), Russian wildrye (Elymus (Scudder); adults of Immediately after the grasshoppers ju n ceus Fisch.) and orchardgrass CamnuZa pellucida (7) (Saussure) and were removed from the cages, the grass (Dactylis glomerata L.). All were Metator pardalinus from each test and check row was cut seeded in 30.5-cm rows at random (8) Bruneria brunnea (Thomas); and at soil level, and oven dried at 74°C. across the width of redwood green- (9) a group of nymphs of mixed for 24 hours. Then the samples were house flats (one row of each species/ rangeland species that ranged from the weighed, and the amount eaten was flat) that had been divided lengthwise second to the fourth instar but not necessarily composed of the same determined by the difference between into two equal parts by a board. Thus test and check rows for each entry. four flats could be placed together in a species as the other species tested. M. These were added for a replicate and rectangular pattern, and a metal-screen sanguinipes is a mixed feeder that eats grasses and forbs (Mulkern et al., the entry data then converted to a cage 101 X 39 X 30 cm could be percentage of the total eaten for that placed over half of each row within a 1964). The other species feed mainly replicate. The data were subjected to flat, while the rows outside the cage on grasses (Anderson and Wright, analysis of variance for detection of served as controls; there were four 1952; Criddle, 1933; Mulkern et al., differences among grasses. Plant means replicates of each grass species per 1969: Ganwere, 1961 and Brooks, (within age groups) were compared by cage. Half of each grass species was 1958). We assumed that the mixed use of Duncan’s multiple range test. planted in May and half 6 weeks later, group of nymphs would consume both so seedling plants and more mature grasses and forbs. Results and Discussion plants could be tested at the same The number of grasshoppers used time. In all, 72 flats and 18 cages were for an infestation ranged from 30 to The relative amount eaten of each

286 JOURNAL OF RANGE MANAGEMENT 27(4), July 1974 Gomm, F. B. 1962. Reseeding studies at a grass species by each grasshopper Table 1. On seedlings, adult A. deorum sma.tl high-altitude park in southwestern group is reported in Table 1. Con- represented the entire group best, and Montana. Montana Agr. Exp. Sta. Bull. sumption varied significantly (P<.Ol) adult C. pehcida was least representa- 568. 16 p. between grass species, and there was a tive. On advanced plants, adult C. Hansen, R. M., and D. N. Ueckert. 1970. significant interaction between grass pelhcida was most representative, and Dietary similarity of some primary con- age and grass species. Green needle- sumers. Ecology 5 1:640-8. nymphs of C. pellucida was least repre- Herman, W., and R. Eslick. 1939. Suscepti- grass and Russian wildrye sustained sentative. bility of seedling grasses to damage by significantly less feeding than the grasshoppers. Amer. Sot. Agron. J. other species, both as seedlings and as Conclusions 31:333-337. Hewitt, G. B. 1968. Resistance of forage advanced plants, and did not differ The results of the tests confirm that plants to the feeding of Melanoplus significantly themselves either within grasshoppers exhibit large differences sanguinipes. Ann. Entomol. Sot. Amer. or between plant ages. Orchardgrass in feeding preference among plant 61:739-744. and smooth brome sustained signifi- species. On the average, that is for four Hewitt, G. B. 1969. Twenty-six varieties of cantly more feeding than the other of the six plant species, these prefer- forage crops evaluated for resistance to species both as seedlings and advanced feeding by Melanoplus sanguinipes. Ann. ences persisted in much the same order Entomol. Sot. Amer. 62:737-741. plants and did not differ either within at two stages of the plant growth. With Isley, F. B. 1938. The relation of Texas or between plant ages. The relative very few exceptions, green needle- to plants and soils. Ecol. amounts of feeding on pubescent grass and Russian wildrye were least Monogr. 8:551-604. wheatgrass and thickspike wheatgrass preferred by all grasshopper species Lambley, J. 1967. Food plant preferences of grasshoppers (: Acrididae) were significantly different within and stages. of selected planted pastures in eastern both plant ages and between plant ages No one grasshopper species or age Kansas. Unpubl. MS dissertation, Kansas but were reversed in order from seed- was clearly representative of all groups State Univ., Manhattan. ling to advanced plants. This reversal tested. However, the group of mixed Mulkem, G. B., D. R. Toczek, and M. A. was the major cause of the indicated Brusven. 1964. Biology and ecology of nymphs appeared to select grass North Dakota grasshoppers. 11. Food interaction between grass age and grass species most uniformly and was fairly habits and preference of grasshoppers species reported for the total test. representative of all grasshopper associated with the sand hills prairie. Our results tend to confirm pre- groups. North Dakota Agr. Exp. Sta. Res. Rep. We concluded that it is feasible to 11,59 p. vious observations. For example, Mulkern, G. B., K. P. Pruess, H. Knutson, A. Hewitt (1968) reported lower average screen plant species in the seedling F. Hagen, J. B. Campbell, and J. D. feeding rates, less weight increase over stage for preference by using grass- Lambley. 1969. Food habits and prefer- four generations, and fewer egg pods hopper nymphs because the nymphs ences of grassland grasshoppers of the selected plant species of both ages north central Great Plains. North Dakota per female over four generations for Agr. Exp. Sta. Bull. No. 48 1, 30 p. M. sanguinipes on green needlegrass about equally well and their prefer- Nerney, N. J., and A. G. Hamilton. 1967. than on Russian wildrye and thick- ences were generally similar to those Field observations of grasshoppers and spike wheatgrass. Also, Hewittt (1969) of adults. This combination would damage surveys on rangeland of San Rafael Valley, Arizona. U. S. Dep. Agr., in working with M, and permit more rapid screening than sanguinipes Agr. Res. Serv. Special Report Z-202. 13 would be the case with older plants the same six plant species used in the P* present test found that green needle- and adult grasshoppers, since less time Parker, K. G. 1961. Seeding and using grass gave low nymphal feeding in the would be required for rearing and permanent pastures. Montana Coop. Ext. greenhouse, least adult feeding in the maintenance. Serv. Bull. 312,28 p. field, least survival, and least weight Public Land Law Review Commission. 1970. Literature Cited The forage resource. Public Land Law , gain than any other plant species; Anderson, N. L., and J. C. Wright. 1952. Review Commission, Washington, D.C. Russian wildrye also gave very low Grasshopper investigations on Montana Vol. 2. survival and weight gain. range lands. Montana Agr. Exp. Sta. Putnam, L. G. 1962. Experiments with Tech. Bull. 486,46 p. some native and introduced plants as The analysis of variance did not Brooks, A. R. 1958. Acridoidea of southern food for Camnula pellucida (Scudder) in show significant differences among Alberta, Saskatchewan, and Manitoba western Canada. Canadian J. Plant Sci. grasshopper groups, either as a main (Orthoptera). Can. Entomol. Suppl. 9, 42589-595. factor or in interactions, because of go:92 p. Rauzi, F., R. L. Lang, and C. F. Becker. Chu, I-Wu, and H. Knutson. 1970. Prefer- 1963. Interseeding Russian wildrye into the large error variance. An attempt ences of eight grasshopper species among native shortgrass rangeland. Wyoming was made, however, to compare the eleven species of cultivated grasses, J. Agr. Exp. Sta. Bull. 406. 8 p. feeding of grasshopper groups within Kans. Entomol. Sot. 43:20-31. The Forage Resource, 1970. Public Land plant ages by calculating the mean Criddle, N. 1933. Studies in the biology of Law Review Commission. Wash, D. C. deviation of each group from the North American Acrididae-development Vol. 2. and habits. Proc. World Grain Exhib. Ueckert, D. N. 1968. Seasonal dry weight average of all groups, thus providing an Conf. Canada 2:474-94. composition in grasshopper diets on index as to how well a particular Davis, E. G. 1949. Reducing grasshopper Colorado herbland. Ann. Entomol. Sot. grasshopper species and stage repre- damage by regrassing weedy roadsides Amer. 61:1539-1544. sented all grasshopper species and and fence rows. U. S. Dep. Agr. Circ. Ueckert, D. N., R. M. Hansen, and C. stages tested. Grasshopper groups are 813. 11 p. Terwilliger, Jr. 1972. Influence of plant Gangwere, S. IL 1961. A monograph on frequency and certain morphological arranged by magnitude of deviation food selection in Orthoptera. Trans. variations on diets of rangeland grass- from the average for each plant age in Amer. Entomol. Sot. 87:67-230. hoppers. J. Range Manage. 25:61-65.

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