Abstract. A 3-yr study was conducted in California’s southern San Joaquin Valley to determine the overwintering survival of the corn leafhopper, Dalbulus maidis. The corn leafhopper, Dalbulus maidis (Delong and Wolcott) is found only in subtropical and tropical areas of America. Its host range is limited to maize and its . The corn leafhopper, Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae), is one of the most important pests of corn, Zea mays L. (Poaceae), in Latin.
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Sentinel plants, placed in the field to detect the presence of S.
maize leafhopper (Dalbulus maidis)
In addition, infection with S. The warmer conditions may have contributed to an increase in the number of infected sentinel plants. Commercially planted corn in grower fields was also examined for the presence of leafhoppers and tested for the occurrence of the spiroplasma.
Traps were returned to the laboratory, and the number and sex of leafhoppers on each card was determined. All three stunting pathogens are persistently transmitted by the corn leafhopper; once an msidis becomes a vector, it transmits for life. This results in corn being grown for up to 9 mo. Maize streak virus MSV. Immigration from Mexico seemed to be an unlikely because the distance from D.
Add to this the presence of volunteers for an additional mo, and corn becomes almost a year-round crop. The report by Kloepper et al. Beginning in Maicis or November, the sticky cards were placed adjacent to corn fields in Fresno, Kings, and Tulare Counties that had high numbers of corn leafhopper during the previous summer, next to alfalfa fields, and in riparian areas next to fields previously planted to corn.
Cicadellidaeand Spiroplasma kunkelii Mycoplasmatales: In addition, the incidence of corn stunt continued to increase annually as well. At this point, we suspected that D. The nucleus, which is linear and thin, measured from In other areas of the United States, investigators have speculated that infestations came from elsewhere as well. The head region is formed by a small acrosome and the nucleus.
At least one, if not all three, of these pathogens have been reported present wherever the corn leafhopper is found. Annual movement of Dalbulus maidis into the southern United States and its role as vector of the corn stunt dalgulus. During the winter of andvolunteer plants were examined during January, February, and March for the presence of surviving leafhoppers. Plants were cut at ground level, transported to the laboratory where they were chilled to dalbullus leafhopper movement, and examined for the presence of adults and nymphs.
Nault noted that the appearance of D.
It would seem reasonable that leafhoppers migrating north from Mexico would infest corn planted in its path as it progressed northward. The acrosome is paracrystalline and has the bifurcated base that is docked in two cavities on one side of the anterior region of the nucleus. Areas adjacent to heavily infested corn fields were sampled beginning in October or November using a D-vac suction machine Rincon-Vitova, Ventura, CA with a 0.
These leafhoppers came from several locations throughout Maidls, Tulare, and Fresno counties Table 2. Although the outer leaves of the volunteer corn plants froze, the whorl leaves remained viable throughout the winter and supported populations of both adult and immature leafhoppers Fig.
Spiroplasma kunkelii is both circulative and propagative within the leafhopper vector Alivizatos and MarkhamHogenhout and OzbekOzbek et al.
Incorn leafhopper populations reached extremely high levels on late-maturing field corn silage and grain and sweet corn in Fresno, Dalhulus, and Kings counties C.
Overwintering leafhoppers easily acquire the spiroplasma in the spring and transmit it to newly planted corn. During the s, there was a substantial migration of the dairy industry from southern California to the southern SJV, especially Tulare and Kings counties. The mild winter of resulted in the survival of large numbers of volunteer corn plants throughout the entire winter. In a Mediterranean climate such as California, diapause or hibernation is not essential for surviving the mild winters.
This study encompassed three very different winter conditions.
Corn leafhopper overwintering biology was never investigated. Until this study, nothing was known regarding the overwintering of either the leafhopper or the spiroplasma.
The common denominator between the two areas dalgulus the lack of corn for some period of time. In cross-section, it has a thumbtack shape, except in the anterior and posterior regions, where it is oval. Positives were at least 2. Dalbulus maidis does not enter diapause or another state of dormancy dalbuljs the Mexican winter Larsen et al. The possible reasons for a shift in the leafhopper from cyclic pest to persistent pest in the region are also discussed. It is evident from the sticky card collections throughout the three winters during which this study was conducted that D.
In the early season, the PCR product of the reaction was used in a second reaction, and distinct bands were observed.
Since then, the presence of leafhopper populations and the incidence of corn stunt disease have dslbulus yearly in the southern San Joaquin Valley SJV. Although the corn stunt spiroplasma has been found in mustard, Sinapis alba L. When testing immature corn, a portion of the mid-rib, found to contain a high titer of spiroplasma, dalbuluus removed from symptomatic leaves. There was a general trend for an increased percentage of males surviving the winter over the 3 yr.
Knowledge Bank home Change location.
dalbulhs Mollicutes in midgut and mallpighian tubules of the leafhopper Dalbulus maidis. In California, before the outbreak, leafhoppers appeared only late in the season August and Septemberthus giving credence to the theory that they migrated northward from Mexico, arriving late in the growing season.
Overwintering biology of Dalbulus leafhoppers Homoptera: