Glandular Trichome Extracts from Medicago sativa Deter Settling by the Potato Leafhopper Empoasca fabae

Extracts of glandular trichomes from Medicago sativa were tested for their ability to disrupt the settling behavior of the potato leafhopper, Empoasca fabae. Erect and procumbent glandular trichomes were mechanically isolated from stem sections of resistant genotype "G98A," and nonglandular trichomes were collected from susceptible cultivar "Ranger." Isolated trichomes were extracted with chloroform, acetone, and ethanol, and the resulting crude extracts were applied to the surface of a sachet containing an artificial diet. Leafhoppers were offered a two-way choice between crude trichome extracts from G98A and Ranger. All three of G98A solvent extracts caused various degrees of diet rejection, resulting in the crude Ranger trichome extracts being preferred over G98A extracts. Overall, the fewest leafhoppers settled on the ethanolic extracts. Additional bioassays documented a dose response associated with G98A ethanolic extracts when compared with Ranger trichome extracts and a solvent control. No difference in preference behavior was detected between Ranger trichome extracts and a solvent control. Gas chromatography-mass spectrometry analysis revealed a homologous series of nonvolatile fatty acid amides C(n)H(2n+1)NO (n = 19-23) unique to G98A glandular trichome extracts.     

Effects of Colorado potato beetle and potato leafhopper on amino acid profile of potato foliage

Feeding by Colorado potato beetles and artificial defoliation had a minor effect on the profile of amino acids in potato foliage, whereas feeding by potato leafhoppers caused an increase in about one half of the amino acids measured.     

Interference of sonic communication and mating in leafhopperAmrasca devastans (distant) by certain volatiles

Mating between the two sexes in the leafhopperAmrasca devastans was inhibited by cineole vapors surrounding host plant leaves bearing the insects. There was a decline in the percentage of pairs mating and mated females fertilized. The vapors were not toxic and did not prevent the insects' arrival on the leaves. The cineole vapors inhibited the mating chiefly by interfering with the surface-mediated sonic communication between the sexes. The inhibition of mating was chemical specific since other volatiles, e.g., citral, were not as effective as cineole. Exposure to cineole vapors resulted in a decline in the sexual response of the females to the sonic signals of the male     

Inhibition of oviposition by volatiles of certain plants and chemicals in the leafhopperAmrasca devastons (distant)

Oviposition by the leafhopperAmrasca devastans (Distant) on its susceptible host plant, cotton (Gossypium hirsutum var. PS-10), was inhibited by the volatiles of certain plants and by the vapors of some chemicals occurring in various plants when these were presented at a distance from the ovipositional substrate. The effectiveness of the volatiles of the plants for inhibiting the oviposition decreased in the order: eucalyptus > coriander=castor=tomato > lime,Ocimum being without effect. Among the volatile plant chemicals tested, the inhibitory effects decreased in the order: citral=carvacrol > citronellol=farnesol = geraniol=eucalyptus oil > neem oil=Cymbopogan oil. These chemicals served as volatile antiovipositants and did not reduce the arrival/stay of the insects on the host plants. Carvacrol had a slight toxic effect on the nymphs, but none of the volatiles was toxic to the adults.Homoptera: Cicadellidae.