Female Leafhoppers Research Articles

Phylogeny and Strain Typing of Wolbachia from Yamatotettix flavovittatus Matsumura Leafhoppers.

Wolbachia is a maternally inherited bacterium of insects that can alter the reproduction, biology, and fitness of the hosts. It was detected in natural populations of the Yamatotettix flavovittatus Matsumura leafhoppers, the vector of phytoplasma, which is responsible for sugarcane white leaf disease. Wolbachia infection prolongs the longevity of female leafhoppers and promotes a strong reproductive incompatibility; importantly, highly maternal transmission rate was observed. However, limited data on the diversity or strain typing of Wolbachia in Y. flavovittatus are available. We aimed here to detect the presence of Wolbachia in different populations by amplification of the wsp gene, which was then sequenced. Multilocus sequence typing (MLST) was also performed to explore the diversity of the Wolbachia strains. Based on the wsp sequences, Wolbachia in the Y. flavovittatus leafhoppers belonged to supergroup B, and formed a distinct evolutionary lineage; therefore, we designated this new specific strain as wYfla. The MLST profiles revealed ten potential new sequence types (STs) in different leafhopper populations. Multiple STs were detected in individual leafhoppers, among which the ST-wYfla1 strain was predominant. Furthermore, we obtained congruent results for the phylogenetic analyses using the wsp gene and MLST loci. To the best of our knowledge, this is the first study characterizing Wolbachia strains in Y. flavovittatus. Our results reveal a novel strain and multiple STs of Wolbachia, and these data may prove useful in the exploitation of Wolbachia as a biological Y. flavovittatus control agent.

Investigating the Movement Components of Host Preference in a Highly Mobile Insect Herbivore, Nephotettix cincticeps (Hemiptera: Cicadellidae).

Effective insect management strategies require a firm understanding of the factors determining host preference, particularly in highly mobile insect herbivores. Host preference studies commonly employ average or first position as a proxy for preference. Yet few studies have explored host preference in relation to transitory attraction and leaving rates, yet these are both components of host plant selection. We investigated the transitory dynamics of preference by the green rice leafhopper, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae) by conducting experiments on groups of females, males, or mixed-sex leafhoppers, and recording their position over time between low-N and normal-N rice plants. Utilizing a log-linear model and variants of a biostatistical model we used these positional data to extract attraction, leaving and tenure rates to better understand the process of host-plant selection. We found a general preference for normal-N over low-N plants at equilibrium. However, between sexes there was variation in the relative significance of attraction or leaving rates on that preference. Female leafhoppers were more attracted to host plants with higher nitrogen content. Male leafhoppers were less discriminate in their initial attraction to hosts but left low-N hosts at a faster rate. Whereas estimated tenure times on both normal- and low-N plants exceeded transmission times for the leafhopper-transmitted rice dwarf virus, longer tenure on normal-N plants likely increases the likelihood of virus acquisition from these plants. Our findings support previous recommendations that growers can mitigate the risks of leafhopper damage and pathogen transmission by optimizing their application of nitrogenous fertilizers.

Role of Dalbulus maidis (Hemiptera: Cicadellidae) gender on maizebushy stunt phytoplasma transmission

There is a behavioral difference between male and female of insect vectors of plant pathogens that may reflect on the transmission of such pathogens. Dalbulus maidis is the leafhopper vector of the maize bushy stunt (MBS) phytoplasma. In this work, sex ratio of D. maidis collected directly from the maize whorl or with yellow sticky cards in a field plot in Piracicaba, SP (Brazil) was evaluated during the first month of the crop development. The natural MBS infection of the captured leafhoppers was assessed by PCR and the disease incidence was visually evaluated in the maize plots. Female D. maidis were more easily captured from the maize whorl, whereas male leafhoppers were more abundant in the cards. The incidence of MBS diseased plants in the plot was 21.2%. MBS phytoplasma was detected in 8% of the captured females whilst 2% of males carried the prokaryote. It is possible that the infected leafhoppers in the early stage of the crop contribute to the final disease incidence. Additionally, the acquisition and transmission rates to maize seedlings by males and females of D. maidis, virgin or mated, was studied. Acquisition rate of MBS phytoplasma was not significantly different between male and female leaf hoppers, however, female, either virgin or mated, transmitted the phytoplasma in a higher rate than males. The behavior of females of spending more time on the plant feeding may explain the higher natural infection of MBS phytoplasma in field condition and the increased transmission rate observed in the experiment.

Identification of Empoasca onukii (Hemiptera: Cicadellidae) and Monitoring of its Populations in the Tea Plantations of South China.

Tea green leafhoppers (Empoasca spp.) are considered one of the major pests in tea plantations in Asia. They are, however, difficult to monitor due to their size and flying and jumping abilities. In this study, we clarified the identification of the leafhopper species encountered in our study plantations and examined the impacts of sampling methods in estimating population abundance and sex ratio. The natural sex ratio of eggs, nymphs, and adults of tea green leafhopper and the differences between male and female were tested. Despite previous reports that Empoasca vitis (Goethe) was the major leafhopper present in our study area, our results showed that only Empoasca onukii Matsuda was found. Variation in population size over time and bias in sex ratio depending on the sampling methods were found in our monitoring experiments. In general, adult males were more attracted to yellow sticky cards than females. We believe that because female leafhoppers should be the target in pest control, yellow sticky cards may not be the most suitable monitoring or effective control of tea green leafhopper. We demonstrate the importance of understanding the implications of sampling techniques for population estimation and sex ratio bias as well as how temporal variation may affect monitoring results. Precise monitoring should take into consideration the different life histories of male and female.

Temporal Distribution of Aster Leafhopper Sex Ratios and Spatial Pattern of Aster Yellows Phytoplasma Disease in Lettuce

The aster leafhopper, Macrosteles quadrilineatus Forbes, is an important pest of fresh market vegetable crops as the primary vector of the aster yellows (AY) phytoplasma. Two sampling methods, sticky trapping and inverted cage trapping, were used to monitor male and female leafhopper populations over three growing seasons in leaf lettuce fields in Ohio. Captures by one sampling method could not be used to estimate captures by the other method, because sticky traps captured significantly more male leafhoppers and cage traps captured significantly more females. The proportion of females collected in cage traps decreased significantly in individual plantings as lettuce matured and also over the course of the season in one of 2 yr of sampling by using both techniques. Subsamples of captured leafhoppers were tested for AY phytoplasma infection by using a polymerase chain reaction (PCR) assay. In one year of our study, more male than female leafhoppers were infected with AY phytoplasma. Because the field distribution of insect-vectored diseases can reveal information about vector movement, as well as vector identity, spatial analysis was performed. Analyses indicated the distribution of symptomatic AY phytoplasma-infected lettuce plants was significantly clustered and followed a beta-binomial distribution. Our data suggest that females may be responsible for at least the early season inoculation of clustered symptomatic lettuce plants.

Effect of environmental conditions and leafhopper gender on Maize chlorotic dwarf virus transmission by Graminella nigrifrons (Homoptera: Cicadellidae).

To determine the most economical and efficient means to maintain cultures of Maize chlorotic dwarf virus (MCDV) and to screen for host plant resistance to MCDV, we evaluated the effects of temperature, light intensity, daylength, atmospheric pressure, and leafhopper gender on the frequency of transmission of MCDV by Grarminella nigrifrons Forbes (Homoptera: Cicadellidae). Female leafhoppers transmitted at higher frequencies than males under most conditions. In temperature studies, transmission rates for both male and female leafhoppers progressively increased as temperatures rose from 20 to 30 degrees C. At high light intensities, both males and females transmitted at greater frequencies than they did at low. Similarly, longer day lengths were correlated with higher transmission rates for both sexes. No significant differences in transmission rates were observed in response to differences in atmospheric pressure. The results also showed that transmission rates under most conditions are high enough to overcome potential ambiguities caused by inoculated susceptible plants that do not become infected (disease escapes) when screening for resistance.

Nitrogen Fertilization and Use of Container-grown Maple Selections as Hosts by the Potato Leafhopper

The suitability of container-grown clones of red maple, Acer rubrum L., as a host to the potato leafhopper, Empoasca fabae Harris (Homoptera: Cicadellidae), under different fertilization regimes was determined, and compared to different freeman maple cultivars (A. ×freemanii E. Murray). Three clonal selections of red maple (USNA numbers 56026, 59904, and 55410), and three freeman maple cultivars (55892 `Indian Summer', 67256 `Jeffersred' [trademark Autumn Blaze], and 55890 `Armstrong') were potted in 7.6-L containers, fertilized with either 0, 3.3, or 6.6 g/pot of calcium nitrate and used in experiments. When given a choice, female leafhoppers laid more eggs on leaves of red maple clone 56026 than on leaves of clone 59904, with oviposition linearly increasing on both clones with increases in the fertilization level applied to the trees. Yet, when female leafhoppers were confined to leaves using organza sleeve cages, oviposition increased linearly as fertilizer level increased, without a significant clonal effect. Oviposition did not differ among freeman maple cultivars, nor was it influenced by the fertilizer level applied to the freeman maple trees. Nymphs had the lowest odds of surviving to adulthood when reared on the freeman maple `Jeffersred', but highest when reared on red maple 59904. Red maple 59904 had the fastest growth rate while red maple 55410 had the slowest. Leaf initiation and expansion in red maple 56026 was significantly slower than in the other selections. Leaf development of these three red maple clones was significantly accelerated by the application of fertilizer, regardless of level. The maple selections differed in their mean amounts of foliar macronutrients and micronutrients, which related to the fertilizer level applied to trees. Unfertilized trees had the highest C to N ratio, which decreased as fertilizer level applied to trees was increased. This study showed that fertilization improved the performance of the potato leafhopper on previously nonpreferred maple selections, and that the foliar nutrient content and C to N ratio could be used as indicators of tree susceptibility to insect attack under different growing conditions.

Repellency to the Potato Leafhopper (Homoptera: Cicadellidae) by Erect Glandular Trichomes on Alfalfa

We sought to gain insights into the mechanism of resistance of glandular-haired alfalfa to the potato leafhopper, by testing the trichomes of proprietary genotypes for chemical versus morphological differences. Two-choice, noncontact tests were conducted using four glandular-haired and one glabrous genotype of alfalfa, representing a spectrum of resistance, to determine whether adult female leafhoppers could detect and be repelled by putative volatiles released from the trichomes. Settling patterns roughly agreed with the degree of resistance reported by industry scientists who provided the plants. Repellency was strong for the most resistant genotypes, and absent with the most susceptible genotype. The remaining, intermediate-to-low-resistance genotypes exhibited variable repellency. A no-choice, plant-contact preference test showed no significant differences in settling among stems left intact or denuded, neither within nor among all genotypes. In all cases, adult leafhoppers settled on glandular-haired alfalfa if given no alternative. Environmental scanning electron microscopy of erect, glandular trichomes of eight proprietary genotypes (including the four used above) showed no obvious morphological differences among genotypes, or between stems and leaves within each genotype, although morphological comparisons were not quantified due to the fragility of the specimens. Taken together, our results suggest that volatile compounds contribute to variable levels of repellency to potato leafhoppers by glandular-haired alfalfa, but that such compounds cannot strongly prevent feeding at all costs.

Influence of Aster Yellows Phytoplasma on the Fitness of Aster Leafhopper (Homoptera: Cicadellidae)

This study revealed that feral aster leafhoppers, Macrosteles quadrilineatus Forbes, exposed to aster yellows phytoplasma live longer and may lay more eggs than nonexposed leafhoppers. Aster leafhoppers were reared on asters infected with either of 2 strains of aster yellows phytoplasma or uninfected asters. After eclosion, adults were placed on uninfected healthy lettuce or oat plants and transferred periodically. The life span of test leafhoppers and the number of offspring they produced were compared. Females reared on noninfected aster plants lived for an average of 19 d, those reared on ‘severe’ and ‘bolt’ strain aster yellows phytoplasma-infected plants lived 26 and 28 d, respectively. The mean number of offspring produced by females reared on the bolt strain of aster yellows phytoplasma-infected asters was almost twice the number produced by nonexposed leafhoppers. The life span of feral leafhoppers or the number of eggs laid did not differ for leafhoppers maintained on either oats or lettuce after exposure to aster yellows phytoplasma-infected asters. Female leafhoppers lived twice as long as males. Our results suggest that the aster leafhopper may have had a long association with aster yellows phytoplasma. The longer life and higher fecundity of phytoplasma-infected leafhoppers may influence disease dynamics of aster yellows in lettuce.

Diel Settling Patterns of Female and Male Potato Leafhoppers (Homoptera: Cicadellidae) on Alfalfa

Settling of male and female potato leafhoppers, Empoasca fabae (Harris), were compared over a diel regime (16:8 [L:D] h) on alfalfa, Medicago sativa L. cultivar ‘Ranger’, in the laboratory. On average, >80% of the females and 50% of the males were recorded on stems. Leaves were used more frequently by males than by females, but little use was made of the upper leaf surface by either sex. The proportions of both males and females on stems declined over time, whereas over time the proportion of males increased on leaves. Based on stem and leaf surface area available to leafhoppers, both sexes preferred stems and avoided leaves. Scotophase did not appear to alter the dynamics of leafhopper distribution. Females more frequently caused expression of injury symptoms in the alfalfa stems than did males in a 36-h access period. Thus, use of females in electronic monitoring and other feeding studies of adults for assessing injury to plants is supported for studies that are 36 h or shorter and where gender is not germane.

Leafhopper (Homoptera: Cicadellidae) Transmission of Aster Yellows Phytoplasma: Does Gender Matter?: Fig. 1.

Male and female aster leafhoppers, Macrosteles quadrilineatus Forbes, differ in their ability to transmit the aster yellows phytoplasma. In laboratory and greenhouse experiments, males were up to twice as likely as females to acquire and become infected with aster yellows phytoplasma as measured by polymerase chain reaction analysis. Yet, in 3 different experimental arenas, infected females were significantly more likely than infected males to transmit aster yellows phytoplasma. When confined on single leaves, more females (55%) than males (35%) transmitted phytoplasma to lettuce plants. In cages with access to 4 lettuce plants, females transmitted to 18% and males to 8% of the plants. When leafhoppers were released in the greenhouse, where leafhoppers were relatively unrestricted in their movement, females transmitted to 29.8% and males to 10.1% of lettuce plants. The pattern of spread by females in the greenhouse was significantly more clustered than that by males. The different movement and feeding behaviors of males and females may explain, in part, differences observed. We conclude that gender does matter in transmission of aster yellows phytoplasma by the aster leafhopper.

Differences in Cellular Abnormalities Induced by the Probing Behaviors of Empoasca kraemeri (Homoptera: Cicadellidae) on Tolerant and Susceptible Common Beans

Cellular abnormalities induced by the feeding behavior of Empoasca kraemeri Ross & Moore were studied in 2 tolerant lines ('EMP 84' and 'EMP 392'), an intermediate ('Porrillo sintetico') and a susceptible ('Calima') cultivar of Phaseolus vulgaris L. Groups of two 3- to 4-d-old Female leafhoppers were placed for 3 h in l clip cage per plant, each covering 1cm2 of fully expanded primary laeves, 1 5 dafter planting. Leaf tissues were fixed 48 h after this access period and prepared for light and confocal microscopy. Damage to the leaf lamina in all genotypes included cell emptying and breakage of cell walls, as well as enlarged intercellular spaces in the palisade and spongy parenchyma. In the main vascular bundle, hypertrophied parenchyma cells plus cells with enlarged nuclei and stained nucleoli were observed. In general, cellular damage was less severe in the tolerant lines than in the susceptible genotypes, although more so for EMP 84 than for EMP 392. Morphometry of autofluorescent tracheary elements showed what seems to be a compensatory response to leafhopper attack in the tolerant lines. Although control leaves from tolerant lines had fewer tracheary elements per vascular bundle after leafhopper feeding, EMP 84 had more tracheary elements in damaged tissues. Both tolerant genotypes had tracheary elements with larger internal radii, which increased their estimated relative flow rates. The implications of cellular damage for the onset of hopperburn, in bean as well as other host plants such as alfalfa and potato, and the mechanisms of tolerance are discussed.

Quantification of DNA from the Aster Yellows Mycoplasmalike Organism in Aster Leafhoppers ( Macrosteles fascifrons Stål) by a Competitive Polymerase Chain Reaction

Summary A rapid and accurate assay was developed for the quantification of the aster yellows plant pathogenic mycoplasmalike organism (MLO). The assay was based on the competitive polymerase chain reaction (PCR) technique using the MLO 23S ribosomal gene and adjacent sequence as target template. Amplification from this region was MLO-specific, and DNA from several different aster yellows MLO strains yielded PCR products. For the internal standard, a PCR product was cloned from Bacillus cereus after amplification with the target primers under reduced annealing stringency. Coamplification of MLO and internal standard DNA provided accurate quantification of 1 to 10 7 copies of MLO target DNA. The assay was used to quantify the aster yellows MLO in aster leafhoppers ( Macrosteles fascifrons Stal) after the insects had fed on MLO-infected plants. Female leafhoppers accumulated MLOs much faster than males during the first 15 days following feeding. From 20 to 39 days after initial exposure, the concentration of MLOs in male leafhoppers remained approximately half that of females. Initially, the difference in MLO concentration between male and female leafhoppers may have been due to a greater amount of feeding, and therefore MLO uptake, by female leafhoppers. Later, the difference may have been related to the larger body weight of female leafhoppers. By 39 days after infection, the MLO population had reached stationary phase in the insect, and MLO DNA detected by the assay comprised 0.8–0.9% of the total DNA content of infected leafhoppers.

Effects of Host-Plant Nitrogen on the Preference and Performance of Laboratory Populations of Carneocephala floridana (Homoptera: Cicadellidae)

Cameocephala floridana Ball is an oligophagous leafhopper that switches host plants seasonally and feeds primarily on the salt-marsh cord grass, Spartina alterniflora Loiseleur-Deslongchamps, during the winter. In the laboratory, we examined how variation in foliar nitrogen of S. altemiflora influenced the choice of cord-grass culms by C. floridana as feeding and oviposition sites. We also examined the effects of host-plant nitrogen on leafhopper oviposition rate, body size, and fecundity. Given a choice among cord-grass culms grown under four fertilization regimes, groups of adult female leafhoppers preferentially fed on culms that were higher in foliar nitrogen. Although the total number of eggs laid was highest on plants of superior quality (as measured by nitrogen content), the rate of oviposition did not differ among plants of different nitrogen levels. Leafhoppers reared from first instar to adult on highly fertilized plants were significantly larger (had higher dry body weight) than those reared on unfertilized or minimally fertilized plants. A significant relationship between body weight and maternal sibship was also found for males, but not for females. Larger body size is advantageous because larger adult females have higher daily oviposition rates than smaller ones. We suggest that C. floridana that choose plants with higher nitrogen content under natural conditions enjoy a selective advantage and that choice within a host-plant species (and perhaps among species) is correlated with host-plant nitrogen content.

Feeding Behavior of the Potato Leafhopper (Homoptera: Cicadellidae) on Chlordime form- and Phosmet-Treated Alfalfa

The feeding behavior of the potato leafhopper, Empoasca fabae (Harris), on Chlordimeform- and phosmet-treated alfalfa, Medicago sativa (L.), was investigated using an alternating current electronic monitoring system. Feeding of adult female leafhoppers was recorded on alfalfa stems dipped in 100-ppm chlordimeform or phosmet emulsions and compared with that on stems dipped in a control solution of acetone plus surfactant. The potato leafhopper normally feeds by making numerous short duration probes, which consist of one or more distinctive feeding patterns. The presence of chlordimeform and phosmet on alfalfa stems significantly reduced probing frequency and total probing duration. However, on chlordimeform-treated alfalfa, the duration of individual probes was significantly longer. The individual probes of chlordimeform-exposed leafhoppers were significantly longer during the first 30 min of exposure, suggesting that chlordimeform interferes with processes that are responsible for probe initiation and termination. Phosmet treatment resulted in 25% mortality and other symptoms of toxicity after 120 min of exposure.

Ovipositional Sites of the Potato Leafhopper (Homoptera: Cicadellidae) on Vegetative Stage Soybean Plants

Ovipositional site selection of the potato leafhopper, Empoasca fabae (Harris), was studied on five early vegetative growth stages of ‘Essex’ soybeans. In a greenhouse study, plants were exposed to female leafhoppers for 24 h, whereas a natural population was allowed to oviposit on the plants in a field study. After oviposition, plants were divided into predetermined morphological parts, and eggs were counted utilizing a staining technique. Results from the greenhouse study indicated that oviposition in the stems predominates in stages VC and V1 contrasted with primarily leaf oviposition in stages V2, V3 and V4. The total number of eggs per plant generally was greater in older than in younger plants. Among the stem sections, that portion between the cotyledon and unifoliolates was preferred for oviposition. Among the leaf parts, the petioles and midribs were preferred for oviposition with the petiolules and other veins less preferred. Within a growth stage, whether leaf or stem tissue, the newest (i.e., apical) part was preferred over older tissue.

Temperature Effect on Development and Morphometrics of the Potato Leafhopper1

Development and mortality of the potato leafhopper [ Empoasca fabae (Harris)] were studied in the laboratory under constant temperature regimes. Lower thresholds for egg and nymphal development were 7.6 and 8.8°C, respectively, and the upper threshold for development was ca. 29°C. Nymphal mortality was high at 13°C, decreased at 18°C, and gradually increased to 81% at 35°C. Most mortality occurred in the first and fifth instars. Adult measurements indicated differences in size of head capsule width and body length due to sex, differences in whole length due to sex and temperature, and differences in wing length due to temperature. Centigrade degree day (CDD) accumulation for egg development was related to field monitoring of alfalfa for leafhopper eggs, nymphs, and adults during the spring of 1976 and 1977 in Montgomery Co., VA. Calculated CDD from first females collected to nymphal hatch and from first observed eggs to nymphal hatch was 199 ± 20.4 and 136±39.7 respectively. This system could be used in an alfalfa scouting program to indicate when nymphal samples should be collected based on accumulated temperatures after arrival of female potato leafhoppers in the spring.

Emergence Trap and Sweep Net Sampling for Adults of the Potato Leafhopper from Alfalfa12

Adults of Empoasca fabae (Harris) were sampled from alfalfa under varying field conditions by using a newly designed emergence trap, absolute density determinations, and the sweep net. Efficiency of the emergence trap in collecting adults was not significantly affected by wind, temperatures, or alfalfa height. However, decreasing solar intensity resulted in a significantly decreased efficiency as predicted by the equation, E = 0.87S0.36 (E = efficiency, S = cal/cm2/min). At solar intensities greater than 0.8 cal/cm2/min, the emergence trap gave a good estimate (80%) of absolute density. Wind velocity and, to a much lesser extent, temperature were the 2 important variables affecting sweep net catches. When pendular sweeps were used, the relationship of sweep net catches to wind velocity was predicted by the equation, M = 0.075 (1.205)w (M = sweep net conversion factor, W = wind speed (m/sec)). The ratio for pendular vs. 180° sweeps for adult E. fabae was 0.48:1. Absolute density ranged from 17.6–66.0 per m2 and the average sex ratio of males to females was 1.5:1. Female leafhoppers were caught more frequently in sweeps and less frequently in emergence traps than expected, probably due to lessened flight activity of females relative to males.

Transmission characteristics and host range of the clover yellow edge agent

A disease of clover, designated as clover yellow edge (CYE), was transmitted by Aphrodes bicinctus (Schrank) but not by the leafhoppers Scaphytopius acutus (Say), Macrosteles fascifrons (Stal), Agallia constricta Van Duzee, and Agallia quadripunctata Prov. or a Cercopid sp. Transmission by A. bicinctus, given various acquisition access periods on infected clover as nymphs, increased from 29% for 1 day to 67% for 14 days for females and from 42% for 1 day to 72% for 14 days for males. When leafhoppers were given similar acquisition access periods as adults, transmission ranged from 5% for 1 day to 24% for 14 days for females and from 25% for 1 day to 33% for 14 days for males. Inoculative female leafhoppers, given inoculation access periods ranging from 0.5 h to 96 h, began transmitting with 1-h feeds (29%) and reached a maximum with 96-h feeds (88%). Inoculative males began transmitting with 8-h feeds (50%) and reached a maximum with 48-h feeds (83%), the longest time tested. The average preinfective period for female and male leafhoppers tested individually was 42.2 days and 40.1 days, respectively. Once an insect became inoculative, it continued to transmit until death.Of the 31 plant species in 12 families tested as hosts of the clover yellow edge agent (CYEA). 15 species in 6 families developed symptoms. The most commonly observed symptoms were chlorosis or yellowing of leaf margins and reduction in the size of flowers and leaves. Aphrodes bicinctus transmitted CYEA to clover from eight of eight infected plant species tested as source hosts.

Aphrodes bicincta1 as a Vector of the Clover Phyllody Agent

Transmission of clover phyllody agent (CPA) by Aphrodes bicincta (Schrank), given various acquisition access periods on infected clover plants as nymphs, increased from 13.3% for 1 h to a maximum of 82.4% for 24 h for males and from 2.9% for 1 h to a maximum of 89.5% for 216 h for females. Neither sex transmitted with acquisition access periods of 0.5 h. When adult female leafhoppers were given similar acquisition access periods, transmission increased from 2.6% for 1 h to 60% for 216 h. Inoculative female leafhoppers, given inoculation access periods on clover ranging from 0.5 to 216 h, began transmitting during 1-h feeds (29%) and reached a maximum during 7-day feeds (76%). Inoculative males began transmitting during 2-h feeds (33%) and reached a maximum during 7-day feeds (100%). Transmission by inoculative females became erratic as the insects aged but most insects appeared to retain their inoculativity to within one week of their death. The incubation period in individual leafhoppers varied from 24–27 days to 50–54 days. A. bicincta acquired CPA from 8 of 9 infected species of plants but the number of insects that became inoculative varied with the species used as the source. Clover was more susceptible than aster as a test host for transmission of CPA by A. bicincta.