Graminella Nigrifrons Research Articles

Corn Stunt Vector Leafhopper Attractancy to and Oviposition Preference for Hybrid Dent Corn. II. Graminella nigrifrons1,2

Tests were conducted to determine if corn hybrids known to be susceptible to corn stunt virus are more attractive to or preferred for oviposition by Graminella nigrifrons (Forbes) (Homoptera: Cicadellidae) over apparently resistant hybrids. On the basis of leafhopper counts and rate of egg deposition, susceptible hybrids in general were not preferred over hybrids exhibiting resistance when the leafhoppers were given a choice of hybrids in a field cage. Further, no significant differences in egg laying were obtained when females were confined on individual hybrids and not given a choice of oviposition sites.

Greenhouse Studies of Host Plant Suitability to Graminella nigrifrons, a Vector of Corn Stunt Virus12

The suitability of 34 plant selections, representing 28 species, for feeding, survival, oviposition or nymphet development of the black-faced leafhopper, Graminella nigrifrons (Forbes), was tested in the greenhouse. Of the test leafhoppers, 20% or more survived 10 days on 14 of 30 test plants. Percent survival of females was significantly higher than that of males. Twelve of 30 test plants had 20 or more eggs laid in them within a 10-day period. Millet, oats, rice, and sorghum with 67, 56, 54, and 51 eggs, respectively, were the preferred hosts for oviposition. Incubation of eggs varied from 13 to 19 days on 12 test plants, being shortest on barley, oats, and rye and longest on common Bermuda grass. Development of nymphs to adulthood required from 17 to 18 clays on 9 plant species. Nymphs were observed on 29 of 33 test plants. However development to adulthood occurred on only 15 of these. Barley and rye appeared to be good hosts for colony development, while millet, oats, tall fescue, orchard grass, wheat, and perennial ryegrass were considered fair to poor host plants.

Leafhopper1 Populations on Ten Corn Inbred Lines at Florence, South Carolina2

The leafhopper species most frequently collected from corn lines at Florence, S. C, in 1967 were, in order of decreasing abundance, the aster leafhopper, Macrosteles fascifrons (Stal) ; Graminella nigrifrons (Forbes) Stirellus bicolor (Van Duzee) ; Deltocephalus spp.; and Exitianus exitiosus (Uhler). M. fascifrons and G. nigrifrons combined made up at least 77% of the total leafhopper collection on each of 4 collection dates. Populations of the predominant leafhopper species were as high on corn lines tolerant to corn stunt virus as on susceptible lines, indicating that tolerance to this disease is not dependent on the degree of attractiveness of corn to the leafhopper vectors.

Studies on the Field Biology of Graminella nigrifrons,1 a Vector of Corn Stunt Virus in Mississippi2

There are at least 3 generations of the black-faced leafhopper, Graminella nigrifrons (Forbes), in Mississippi. These generations, represented by peaks of adult activity, may be referred to as the spring, summer, and fall generations. High populations of this vector of corn stunt virus in April in the northern portion of the State occur about the time of spring corn planting. Although leafhopper infectivity is low (less than 1% of the natural population) the large first generation is most destructive to young corn. The second generation of leafhoppers is of lesser concern because the crop is older when exposed. G. nigrifrons survives through the winter as both adults and eggs on winter grasses, grain, and grazing crops. Adult leafhoppers actively lay fertile eggs in warm periods during the winter; thus there is no apparent diapause.

Corn Stunt Virus: Transmission by Three Cicadellid Vectors1

The duration of nymphal instars of Dalbulus maidis (DeLong & Wolcott), D. elimatus (Ball), and Graminella nigrifrons (Forbes) was 18.5, 20.2, and 23.5 days, respectively, at 24±2°C. The life span of adult D. maidis, D. elimatus , and G. nigrifrons was 56.5, 51.5, and 38.2 days, respectively. G. nigrifrons was inefficient in acquisition and transmission of corn stunt virus (CSV) to plants in comparison with both Dalbulus species. D. elimatus was able to acquire CSV during access feeding times of 15 minutes. G. nigrifrons and both species of Dalbulus transmitted virus during 4-hour and 15-minute inoculation access feeding periods, respectively, but not at shorter periods. The minimum incubation period of CSV in colonies of the 3 leafhoppers ranged from 22 to 26 days in G. nigrifrons , 17 to 22 days in D. maidis , and 14 to 15 days in D. elimatus at 24±2°C. The frequency of virus transmission by G. nigrifrons and D. elimatus showed that infective insects of both species transmitted virus to almost every plant they were transferred to at 1-, 2-, and 4-day intervals. Poor and efficient vectors were observed in both species. In spite of its comparative inefficiency in acquisition and transmission of CSV, G. nigrifrons might play an important role in the spread of the virus, since it is abundant throughout the corn-growing areas of North America, and it can survive on a variety of plant hosts.

Systemic Insecticides for Control of the Black-Faced Leafhopper, Graminella nigrifrons, and Effect on Corn Stunt Disease1

Three soil systemic insecticides, Baygon® (o-isopropoxphenyl methylcarbamate), disulfoton, and Furadan® (Niagara 10242) (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate), were tested in 1967 for their efficacy against Graminella nigriforons (Forbes), vector of com stunt virus. Experimental plots (0.25 acre) in 3 replications of a randomized complete block design were treated with insecticide as in-furrow applications only or as in-furrow plus side-dress applications at 1 lb/acre 5 weeks after planting. Significantly fewer leafhoppers were collected in Furadan treatment plots and in the Baygon furrow plus side-dress treatment than in the other treatments, Vector control was reflected in disease incidence data; those treatment plots with smaller leafhopper populations had fewer diseased plants than plots harboring larger vector populations. Side-dress applications of Furadan and Baygon 5 weeks after planting increased the efficiency of these materials to a higher level of leafhopper control. Furadan plots receiving a supplemental side-dress application did not have a lower incidence of disease compared with plots treated with this insecticide in-furrow only. Side-dressing with Bagron and disulfoton reduced disease incidence; however these 2 materials were in general less effective than Furadan.

Seasonal Incidence of Indigenous Leafhoppers (Homoptera: Cicadellidae) on Corn and Several Winter Crops in Mississippi1

At least 36 species of leafhoppers were collected on corn and from plots of winter grasses and grains (oat, ryegrass, wheat, and bahia grass) in the vicinity of State College, Miss., in 1965–66. Of the 33 that were found on corn (30 species in 1965, 26 in 1966), 12 were sufficiently numerous so that each constituted 1% or more of each season's total leaf hopper collections. The other 21 (15 species in 1965, 14 in 1966) were considered miscellaneous species which occurred only incidentally on corn. Graminella nigrifrons (Forbes) and Macrosteles fascifrons (Stal) accounted for 36.5% and 12.5%, and 54.0% and 23.0%, of the total seasonal leafhopper collections in 1965 and 1966, respectively. They were the predominant species in both years, and were collected during every semimonthly collection period. In general, leafhopper populations on corn reached high levels in late May and June, declined in July, and increased to high levels again in August and September. Bahia grass was an excellent winter host for M. fascifrons , but most leafhoppers preferred oat and ryegrass. G. nigrifrons , M. fascifrons , Deltocephalus sonorous Ball, and Balclutha sp. were the predominant leafhoppers during the winter. Five other species— Exitianus exitiosus (Uhler), Draeculacephala portola Ball, D. balli Van Duzee, Empoasca sp., and Aceratagallia sp.—were present in the test area throughout the year. Agallia constricta Van Duzee, Carncocephala flaviceps (Riley), Stirellus bicolor (Van Duzee), and Chlorotettix viridius (Van Duzee), on the basis of seasonal occurrence and population levels on corn, are other species which may be considered of significance in investigations of possible vectors of corn stunt virus.

Biology of Graminella nigrifrons (Homoptera: Cicadellidae), a Vector of Corn (Maize) Stunt Virus1

Under experimental conditions, the length of time from oviposition to adult emergence for the black-faced leafhopper, Graminella nigrifrons (Forbes), is 30–37 days. Different specimens may have 4, 5, or 6 nymphal instars, but 5 is usual. Adults live about 30 days, with the females producing 10–23 eggs during this time. The species bred freely on several small grains, grasses, sorghums, and maize. The studies confirm field observations that there are at least 2 overlapping broods of the insect annually. Literature covering nomenclature, host plants, and distribution of the insect is reviewed. The synonomy of the species is given. Detailed data of the stadia of the life cycle, fecundity, and experimental plant host range are presented. Field biology is discussed and the various developmental forms are figured.