Graminella Nigrifrons Research Articles

Transmission of Sorghum Stunt Mosaic Rhabdovirus by the Leafhopper Vector, Graminella sonora (Homoptera: Cicadellidae).

The transmission parameters of sorghum stunt mosaic rhabdovirus (SSMV) by the leafhopper Graminella sonora were determined. The minimum acquisition and inoculation times were 6 and 1 h, respectively, while 100% transmission was obtained from a 48-h acquisition access or a 24-h inoculation access period. Transmission efficiency was highest at temperatures of 24 to 36°C. The minimum latent period prior to transmission was 9 days at 30°C, with an 11-day incubation period necessary for 100% transmission. After a 14-day incubation period at 16°C, no transmission was obtained; however, doubling the incubation period to 28 days gave high levels of transmission. Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of individual leafhoppers held at 16°C for a 14-day incubation period detected no virus in leafhoppers, whereas over 50% of the leafhoppers had detectable virus after a 28-day incubation period. Graminella nigrifrons and Peregrinus maidis were not able to transmit SSMV.

Morphology of the Digestive and Reproductive Systems of Dalbulus maidis and Graminella nigrifrons (Homoptera: Cicadellidae)

The corn leafhopper, Dalbulus maidis (DeLong and Wolcott) (Homoptera: Cicadellidae) is the principal vector of maize rayado fino marafivirus, corn stunt spiroplasma and maize bushy stunt phytoplasma in tropical and subtropical areas of the Western Hemisphere. The black-faced leafhopper, Graminella nigrifrons (Fobes) (Homoptera: Cicadellidae) is the principal vector of maize chlorotic dwarf waikavirus in North America. The morphology of their digestive and reproductive systems was studied by light microscopy, and illustrations were made to aid in dissection and injection of pathogenic inoculum for various vector-pathogen relation studies. In both species, two salivary glands, located one on each side of the head, extend into the mesothorax. Each gland consists of principal and accessory glands. The former contains an anterior lobe and posterior lobe. Two types of acini are present in the anterior lobe, whereas the posterior lobe has four acini. The accessory glands of D. maidis and G. nigrifrons are very similar rod to elbow-shaped structures. The esophagus of both species is a narrow tube originating from the pharynx and extending to the anterior midgut below the filter chamber. The anterior midgut is a large sac-like structure extending from the metathorax through the entire length of the abdomen, and then ascends backward to the anterior of the midgut to form the filter chamber. The filter chamber of D. maidis has a more complex structure than that of G. nigrifrons. There are two pairs of Malpighian tubules in both species. The central tubule is formed from a pair of fused tubules within the filter chamber; the other tubules extend along the front of the hindgut. In G. nigrifrons the three tubules run parallel to each other along the top of the posterior midgut. In D. maidis, the central tubule and one tubule from the other pair run along the interior of the deep loop of the posterior midgut; the other tubule runs along the exterior of the loop. The ovaries of both species contain six ovarioles. Each ovariole consists of a terminal filament, a germarium, developing oocytes and eggs within follicles and a pedicle. The ovarioles contain six follicles. In G. nigrifrons each ovariole usually contains only one egg within the last follicle whereas the ovarioles of D. maidis often contain two eggs. The ovarioles open into the lateral oviduct, common oviduct and the vagina. The spermathecae open into the common oviduct. A collaterial gland and accessory glands are present. The male of both species has two lateral testes each with six follicles. A pair of accessory glands arise at the posterior of each seminal vesicle and open into the lateral ejaculatory duct.

Leafhoppers on leaves: An analysis of feeding behavior using conditional probabilities

Feeding behavior of four deltocephaline leafhoppers,Graminella nigrifrons, G. oquaka, Amblysellus grex, andDalbulus maidis on maize and johnsongrass was analyzed using an electronic monitoring device. Five distinct waveform patterns were identified: secretion of sheath saliva (salivation), nonvascular probing, nonsieve element ingestion, x-waveform, and phloem ingestion. Waveforms were associated with feeding activities by correlation with light microscopic examination of salivary sheath termination points in leaf tissue and analysis of honeydew excreted by monitored leafhoppers. In previous studies x-waveforms have been reported to occur only when the stylets of homopterans are in contact with the phloem; the function of x-waveforms is poorly understood. There were no differences in time spent salivating or ingesting from nonsieve elements amongG. nigrifrons, G. oquaka andA. grex on either plant.D. maidis differed from other species in phloem probing and feeding behavior; only a small proportion produced x-waveforms, although those that did spent significantly more time in this behavior than other species. Also,D. maidis spent more time than other leafhoppers ingesting from tissues other than sieve elements. Kinetic diagrams of transition probabilities show that probing activities of all species were not random regarding the sequence of behaviors culminating in phloem ingestion. Thirty-five percent ofG. nigrifrons x-waveforms were followed by nonsieve element ingestion. This was consistent with observations showing that salivary sheaths of leafhoppers producing x-waveforms sometimes do not terminate in the phloem, but rather in nearby cells. Phloem ingestion was always preceeded by x-waveforms. The quantitative differences in probing behavior are discussed in relation to ability of these leafhoppers to transmit the phloem-associated maize chlorotic dwarf waikavirus.

Periodicity of Diel Activity of Graminella nigrifrons (Homoptera: Cicadellidae) and Implications for Leafhopper Dispersal

Activity periodicity of Graminella nigrifrons (Forbes) virgin adults on maize seedlings was studied in the laboratory. Light intensity was manipulated to examine its effect on vertical distribution and interplant movement of virgin males and females of different ages. Vertical distribution of G. nigrifrons depended upon light intensity and photoperiod, and varied according to sex and age of leafhoppers. Most males and females stayed within the plant canopy during the photophase. Approximately 60% of the males left the plant canopy after light was reduced to simulate dusk, but most females began this upward vertical movement before dusk. No free-running cycles of vertical movement of females were observed under constant light or darkness, suggesting that movement periodicity is not circadian. Fewer young than older males and females flew above the plant canopy during dusk and scotophase; this suggests that newly eclosed adults may undergo a teneral period before engaging in dispersal flights. Within the canopy, males moved between plants more rapidly than females, and this movement decreased markedly during dusk and scotophase. Implications of activity periodicity for dispersal of G. nigrifrons and spread of maize chlorotic dwarf waikavirus are discussed.

Contrasting effects of sewage sludge and commercial fertilizer on egg to adult development of two herbivorous insect species

Municipal sewage sludge containing heavy metals had a toxic effect on the development of the cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae), one of two herbivorous insects commonly found in an Ohio old-field which had been subjected to long-term sewage sludge application. Soils were removed in 1992 from an old-field following 11 years of heavy nutrient enrichment (1978 to 1988) with applications of either sewage sludge (Milorganite(®)) containing heavy metal contaminants or urea-phosphate fertilizer. Egg to adult development rate and survival of the blackfaced leafhopper, Graminella nigrifrons (Homoptera: Cicadellidae), and the cabbage looper was determined on maize (leafhopper) and broccoli (looper) seedlings grown in soils from sludge-treated, fertilizer-treated, or untreated control plots of the old-field. Fertilizer and sludgetreated soils had higher levels of N. P and organic matter, and a lower pH than the untreated control soils, while sludge-treated soils contained significantly higher concentrations of Cd, Cu, Pb, and Zn. Maize appeared to be unaffected by the three soil treatments, and survival and rate of egg to adult development of the leafhopper was not affected. Broccoli seedlings grown in both the high nutrient fertilizer and sludge soils were greener and larger than broccoli grown in control soils. However, the cabbage looper had significant larval and pupal mortality (25 to 40%) and prolonged egg to adult development on sludge-grown broccoli compared to control and fertilizer treatments. As assimilation into the food chain of heavy metals and other organic pollutants, such as PCBs, is in part a function of the interaction of soil chemistry and type of plant, the application of municipal sludges to old-fields needs to be carefully monitored, as contaminants may have significant developmental and behavioural effects on some secondary links in the old-field food chain.

Leafhopper Transmission and Host Plant Range of Maize Chlorotic Dwarf Waikavirus Strains

Two strains of maize chlorotic dwarf waikavirus (MCDV), the type strain MCDV-T and the recently isolated MCDV-M1, were compared for leafhopper transmission, vector specificity, and host plant range. Leafhopper species tested as vectors and their estimated transmission rates (by single insects) of MCDV-T and MCDV-M1, respectively, were Graminella nigrifrons, 27.0 and 20.4%; Amblysellus grex, 17,5 and 6.7%; Planicephalus flavicostatus, 7.9 and 1.0%; Stirellus bicolor, 5.9 and 1.2%; G. sonora, 1.2 and 2.5%; and Dalbulus maidis, 0.8 and 1.7%. Euscelidius variegatus. Macrosteles quadrilineatus, and Ollarianus strictus were tested as well but did not transmit either strain

Evaluation of Maize Chlorotic Dwarf Virus Resistance in Maize with Multiple Inoculations by Graminella nigrifrons (Homoptera: Cicadellidae)

Disease escapes have hindered the progress of evaluation of maize, Zea mays L. subspp. mays , germ plasm for maize chlorotic dwarf virus (MCDV)resistance. The behavior of the primary leafhopper vector, Graminella nigrifrons (Forbes), is the least controllable variable in the disease evaluation process. This variable was minimized in a compact, multiple-inoculation method in a growth chamber where maize seedlings (2-3 d old) were exposed to a different group of viruliferous leafhoppers at 2-d intervals over a 6-d period. The reactions of fourteen resistant maize inbreds and the standard susceptible inbred Oh28 were determined in three comparative tests between the previous single inoculation method and this multiple-inoculation method. At 2 wk after inoculation, infections were >90% in most inbreds in the multiple-inoculation method. At 3 wk after inoculation (except for one plant in inbred Pall in one test), all plants were infected. In contrast, at 2 and 3 wk after inoculation in the single-inoculation method, MCDV infections averaged 78 and 82%, respectively. In all three tests, the mean percentage transmission at the second and third evaluation was greater in plants with the multiple-inoculation method.

Versatile Pressure Chamber for Insect Behavior Studies

A chamber for evaluating effects of pressure on virus transmission and behavior of the blackfaced leafhopper, Graminella nigrifrons (Forbes), was made from a cylindrical metal container (55 cm high by 41 cm diameter), open at the top. At the open end, a plywood (2 cm [3/4 inch] thick) support rim and a rubber gasket coated with vacuum grease were used to support a polycarbonate lid (1 cm thick) and a plywood (2 cm [3/4 inch] thick) retaining ring. The transparent lid allowed illumination into the pressure chamber. The unit was housed in a growth chamber. Air pressure inside the chamber was controlled by inflating or deflating a rubber inner tube at the bottom of the airtight pressure chamber. A timer-actuated solenoid valve regulated air to the inner tube. Temperature, humidity, and pressure were recorded with a datalogger and transmitted to a computer for analysis. In three 12-h tests with controls set at 2.8 mm mercury (Hg) per h increase and 2.6 mm Hg per h decrease, chamber pressure rose and dropped by an average of 30.7 and by 28.4 mm Hg, respectively. When the controls were set for constant pressure, the pressure fluctuated no more than 0.1 mm Hg in a 12-h period. The transmission of maize chlorotic dwarf virus by leafhoppers that had an acquisition access period in the pressure chamber during falling pressure or exposed to atmospheric pressure was 14 versus 21% for males, 48 versus 49% for females, and 37 versus 43% for both males and females respectively.

Biological factors affecting leafhopper transmission of purified maize chlorotic dwarf machlovirus

AbstractA helper component from maize chlorotic dwarf machlovirus (MCDV)‐infected plants was necessary for insect transmission of purified MCDV. Purified MCDV, WS strain, when acquired by membrane feeding, was transmitted by Graminella nigrifrons (Forbes) (Homoptera:Cicadellidae) which fed first on MCDV (M1 strain)‐infected maize. Conversely, feeding on MCDV‐WS‐infected maize allowed transmission of purified MCDV‐M1, indicating that the helper component was not strain specific. Viruliferous G. nigrifrons lost the ability to transmit MCDV‐M1 after feeding for 24 h on healthy maize, but retained the ability to acquire and transmit purified MCDV‐WS for up to 36 h. When G. nigrifrons fed initially on MCDV‐infected plants and then on a second strain of purified MCDV, the second strain of MCDV could be transmitted alone, suggesting that the helper component from MCDV‐infected plants was something other than the virion itself. Lengthening acquisition feeding of G. nigrifrons on MCDV‐M1‐infected maize or purified MCDV‐WS did not significantly change the transmission frequency of MCDV‐WS. Amblysellus grex (Oman), an experimental vector of MCDV, also transmitted purified MCDV‐WS after an initial acquisition feeding on MCDV‐M1‐infected maize. This suggests that the helper component is not vector species specific.

Influence of Leafhopper (Homoptera: Cicadellidae) Gender and Female Mating Status on Plant Disease Dynamics within a Simple Habitat

The influence of leafhopper, Graminella nigrifrons (Forbes), gender and female mating status on the disease dynamics of leafhopper-transmitted maize chlorotic dwarf machlovirus was examined in a maize, Zea mays L., monoculture. Physical maps of disease incidence showed that diseased plants resulting from the release of males at the center of plots were less aggregated than for female treatments. Disease gradient slopes were compared after fitting the data to the log-logistic disease spread model. The release of males resulted in a mean disease gradient slope that was significantly more shallow than female treatments. Disease dispersion was further characterized using Lloyd's patchiness index, which yielded results that confirmed the analysis of disease gradients. These measures of dispersion also indicated a tendency for disease aggregation resulting from virgin females to be intermediate to males and mated females. Although the level of aggregation was most different for male and mated female treatments, there was no Significant difference between these treatments for overall disease incidence, indicating that the pattern of disease spread, but not overall disease incidence, was influenced. Whereas previous studies have focused on the role of host plant finding by leafhoppers as a determinant of individual movement behavior within a habitat, and consequently pathogen spread, our results suggest that an understanding of mating behavior may contribute to our understanding of plant disease dynamics.

Leafhopper Probing Behavior Associated with Maize Chlorotic Dwarf Virus Transmission to Maize

Maize chlorotic dwarf virus (MCDV) is a semipersistently transmitted, foregut-borne virus, transmitted in the field by the leafhopper, Graminella nigrifrons. When MCDV-inoculative G. nigrifrons were given access periods from 15 min to 4 h on maize test plants, there was a positive correlation between longer access and higher transmission. An electronic insect feeding monitor was used to evaluate components of leafhopper probing associated with MCDV inoculation and to compare the probing behaviors of five MCDV-vector and five nonvector leafhopper species. MCDV transmission occurred only when monitored G. nigrifrons produced x-waveforms (this waveform was recorded from all 16 monitored leafhoppers that transmitted MCDV). This characteristic waveform always was recorded prior to ingestion from phloem by leafhoppers [...]

Spread of Maize Chlorotic Dwarf Virus from Infected Corn and Johnsongrass byGraminella nigrifrons

Early emerged adults (males and females) or last instar nymphs (males, females, or males and females together) of the leafhopper Graminella nigrifrons were allowed to acquire maize chlorotic dwarf virus (MCDV) from corn or johnsongrass source plants positioned in the center of maize plots in 1990. In 1991, two planting dates of maize were tested by using newly emerged adult males, females, or males and females. After leafhopper acquisition and potential flight to other plants, disease incidence was assessed throughout the plots. The log-logistic model provided an acceptable fit to the observed disease gradients (.)

Diel Flight Periodicity of Graminella nigrifrons (Homoptera: Cicadellidae)

The effect of light intensity, temperature, and host-plant age on the diel flight periodicity of Graminella nigrifrons (Forbes) was evaluated under controlled laboratory conditions and in the field. In a controlled environment, leafhoppers reared on young and mature oats responded similarly to changes in light intensity when temperature was held at a constant 26.6 ± 1°C. Most leafhoppers were trapped under low light that simulated dusk and dawn. Activity was low at midday and at night. Temperature altered this flight pattern. When day temperature was 26.6 ± 1°C and night was 18.3 ± 1°C, most leafhoppers were trapped late in the day and peaked at dusk. Few leafhoppers flew at night, but there was a small peak at dawn. In these laboratory experiments, numbers of females and males trapped did not differ greatly. In the field, many more leafhoppers were trapped in July than in June or August. Peak flight for all months was at dusk and then declined to low numbers throughout the night, especially in July. There was little or no flight at dawn when temperatures were at their daily low or during warmer daylight hours. Considerably more males than females were trapped. Crepuscular flight reported here for G. nigrifrons is similar to that reported for leafhoppers and other insects.

Behavioral response ofGraminella nigrifrons (Homoptera: Cicadellidae) to experimentally manipulated vibrational signals

Mate recognition for the leafhopper Graminella nigrifrons(Forbes) occurs when a male spontaneously emits a multisectional vibrational calling song to which females respond by emitting simple pulses. Significant differences were found among males in the duration, number of chirps, and chirp rate within sections of the song and the total song. Repeatability (proportion of total variation due to differences among males) of call features ranged from very low (0.04 for total chirps in song) to high (0.67 for section 3 chirp rate). However, song modification and playback experiments revealed that the variation in the measured song features was not important in determining whether a female will respond. Rather, female response depended only on the presence of two of the three types of pulses which comprise a chirp. These “essential” pulses were found within chirps of all call sections that contain chirps. Manipulation of chirp rates from 0.58 to 2.70 times the normal rate did not affect female response, nor did changing the period of silence between the “essential” pulse types from 0.25 to 1.75 times the normal period. These results suggest that components of the male calling song function in mate recognition but are not used by females to discriminate among conspecific males.

Roles of interplant movement, acoustic communication, and phototaxis in mate-location behavior of the leafhopper Graminella nigrifrons

Male Graminella nigrifrons leafhoppers (Cicadellidae: Homoptera) employ a “call-fly” strategy to find virgin females on oat host plants. Males observed in isolation during daylight hours exhibit a high rate of interplant movement, calling from the lower canopy on each plant visited. Virgin and mated females exhibit little interplant movement. They differ from one another in that virgin females perch on the upper half of plants, whereas mated females perch on the lower half of plants. The positioning of females in the plant canopy is influenced by light. Unlike mated females, virgin females respond to male calls by emitting their own acoustic signals. When virgin females are present on plants visited by males, interplant movement of males ceases, and a localized-upward search of the female bearing plant ensues. Male search is influenced by light. Regardless of whether virgin females were confined to the upper or lower portion of plants, direction of male search was towards a light source used to illuminate above or below the plant canopy. These findings suggest that interplant movement by males and sedentary behavior by females prior to mate recognition and their use of acoustic and phototactic sensory modalities after mate recognition represent previously unrecognized adaptations to problems associated with the use of vibrational signals on plants.

Maize Chlorotic Dwarf Viruslike Particles Associated with the Foregut in Vector and Nonvector Leafhopper Species

Transmission electron microscopy was used to observe viruslike particles (VLP) in thin sections of the foreguts of leafhoppers previously fed on maize plants infected with the semipersistently transmitted maize chlorotic dwarf virus (MCDV). The VLP, of size and shape similar to that of MCDV virions, were found embedded in a semiopaque matrix attached to the cultivar intima of the pharynx, cibarium, and precibarium and occasionally to the inner surface of the maxillary food canal in three cicadellid vector species (Graminella nigrifrons, G. sonora, and Amblysellus grex) and in the nonvector cicadellid Dalbulus maidis; they were not found in the nonvector delphacid Peregrinus maidis (...)

Effect of temperature and host plant on the development of the blackfaced leafhopper

Abstract Population dynamics of the blackfaced leafhopper, Graminella nigrifrons (Forbes) (Homoptera: Cicadellidae), was studied at five temperatures (18, 21, 24, 27, & 30 °C) in the laboratory on seedling maize (Zea mays L.), oats (Avena sativa L.), and the perennial johnsongrass (Sorghum halepense (L.) Pers.). Effects of temperature and host plant on egg to adult mean development time, adult size and weight, and fecundity were determined. Leafhoppers on all three hosts developed fastest at the highest temperature tested (21.3 days), and slowest at the lowest temperature tested (73.2 days). The duration from first to last adult eclosion was shortest at 30 °C, (11.5 days) and longest at 18 °C (43 days). The sex ratio of males to females did not differ from 1:1, but males developed an average of 1.2 days faster than females on all three hosts. Mean percent development/day ranged from 1.4% at 18 °C to 4.7% at 30 °C. The relationship of this development rate and temperature was determined using both a linear model and a variable parameter biophysical model. Based on these models, the developmental threshold is estimated at 12–15 °C. The lowest temperature yielded larger and heavier adults (312 μg, dry weight) than did the highest temperature (225 μg). Fewer leafhoppers developed on the perennial than the annuals at 30 °C and fewer on the annuals than the perennial at 18 ° C. Our results suggest that early in the season johnsongrass and perhaps other perennials are the superior developmental hosts for this leafhopper, whereas in midsummer when temperatures are highest, annuals are the better hosts. Résumé Effet de la température et de la plante-hôte sur le développement de Graminella nigrifrons La dynamique des populations (durée de développement de l'œuf à l'adulte, poids et taille des adultes, fécondité) de G. nigrifrons Forbes (Homop. Cicadellidae) a été étudiée au laboratoire à 5 températures sur plantules de maïs (Zea mays L.), avoine (Avena sativa L.) et sorgho vivace (Shorgum halepense (L.) Pers.). Sur les 3 plantes, les mâles se développent en moyenne 1,2 j plus vite que les femelles. Les relations entre vitesse de développement et température ont été déterminées en utilisant à la fois un modèle linéaire et le modèle biophysique à 2 paramètres de Sharpe & DeMichele (1977). Les températures plus basses donnent des adultes des 2 sexes plus gros et plus lourds. Moins de G. nigrifrons se sont développés sur la graminée vivace que sur les 2 graminées annuelles à la température la plus élevée (30 °C), tandis qu'à la température la plus basse (18 °C) moins de cicadelles se sont développées sur les graminées annuelles. La température semble jouer un rôle significatif en déterminant l'adéquation des plantes comme hôtes convenant au développement de G. nigrifrons. Le potentiel de ponte de cette cicadelle avait été sous-estimé par les étudies précédentes.

Effect of Temperature on the Development of the Blackfaced Leafhopper (Homoptera: Cicadellidae)

A laboratory investigation examined the effects of temperature on development of Graminella nigrifrons (Forbes) using seedling johnsongrass as the host. Daily development for each life stage was calculated. Results indicate no significant differences between developmental rates of male and female G. nigrifrons eggs at the temperatures studied. Male nymphs, however, exhibited significantly faster developmental rates than female nymphs. Using estimated thresholds of development of eggs and female nymphs, it was determined that three generations of the leafhopper per year were likely in central Kentucky.

Influence of Life History of Grasses and Maize Chlorotic Dwarf Virus on the Biotic Potential of the Leafhopper Graminella nigrifrons (Homoptera: Cicadellidae)

Suitability of annual and perennial species of Sorghum, Lolium , and Panicum and of healthy or maize chlorotic dwarf virus (MCDV)-infected maize ( Zea mays L.) was determined for oviposition and development of Graminella nigrifrons (Forbes). Intra- and intergeneric comparisons show that host life history and genus had a significant effect on the number of adult leafhoppers produced, their weight, and their developmental time from egg to adult, as did the interaction of these effects. More and heavier adults were produced on annual Sorghum and Panicum than on their perennial counterparts. Numbers and weights of leafhoppers produced on annual and perennial Lolium were not significantly different. Developmental time from egg to adult was shorter on annual than on perennial Panicum but was not different within Sorghum and Lolium . Numbers of adults and their weights on Sorghum species were greater than on Lolium species, which was greater than on Panicum species. Evidence that annual grasses may be superior to perennials as hosts within a genus for this generalist leafhopper is consistent with recent studies of natural grasslands that show higher leafhopper densities on annuals during the logarithmic phase of plant growth than at any time on perennials. Although healthy maize was an excellent host for G. nigrifrons , MCDV infection improved its suitability. This agrees with previous field (but not laboratory) studies that show young maize to be a suitable host for this leafhopper.

Spread of Maize Chlorotic Dwarf Virus in Maize Fields by its Leafhopper Vector,Graminella nigrifrons

(...) In 1984 and the early plantings of 1985 and 1986, there was little change in b over time. In the late plantings, however, b increased (indicating steeper gradients) between 14 and 21 days after release. At ∼21 days after release, the distance at which y declined to 0.10 (10 %) ranged from 124 to 525 cm. The rates of increase in y over time for the entire plots and at selected distances from the release point were measured using the apparent infection rate (r). There was no discernible effect of distance from the source on r. The r parameter consistently declined over time. Results indicate that MCDV spread can be substantial when viruliferous leafhoppers are introduced into a field of susceptible maize