Influence of the site of oviposition on the level of egg parasitism in the corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae)

AbstractNative parasitoids of the adult Mexican corn leafhopper, Dalbulus elimatus (Ball), and corn leafhopper, Dalbulus maidis (Delong and Wolcott), are described and their rates of parasitism on maize, Zea mays L., common barley, Hordeum vulgare L., and sorghum, Sorghumbicolor (L.) Moench (Poaceae) in central Mexico are determined. The survey was conducted throughout an annual cycle, with sampling of the previous season's crops when they were available. Leafhoppers showing evidence of parasitism were reared individually in the laboratory to obtain adult parasitoids. Adult D. elimatus were parasitized on winter maize, barley, and sorghum by the fly Eudorylas subopacus (Loew) (Diptera: Pipunculidae) and the wasp Gonatopus bartletti Olmi (Hymenoptera: Dryinidae), whereas adult D. maidis were parasitized by these fly and wasp parasitoids on winter maize only. The highest rates of parasitism of D. elimatus by E. subopacus were 57.4% on maize, 39.6% on barley, and 48.8% on sorghum. The highest rate of parasitism of D. maidis by E. subopacus was 20.4% on maize. In contrast, the highest rates of parasitism of D. elimatus by G. bartletti were 9.4% on maize, 2.7% on barley, and 25.8% on sorghum. The highest rate of parasitism of D. maidis by G. bartletti was 7.1% on maize. These results indicate that winter crops are habitats of E. subopacus and G. bartletti during the winter season. This is the first report of D. elimatus and D. maidis being parasitized by E. subopacus and of D. elimatus being parasitized by G. bartletti.

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Probing behavior of the corn leafhopper Dalbulus maidis on susceptible and resistant maize hybrids

10.1101/2021.10.21.465285 ◽

2021 ◽

Author(s):

Pablo Carpane ◽

María Inés Catalano

Keyword(s):

Total Duration ◽

Electrical Penetration Graph ◽

Corn Hybrids ◽

Dalbulus Maidis ◽

Maize Hybrids ◽

Probing Behavior ◽

Corn Stunt ◽

Corn Leafhopper ◽

Old Females ◽

Mesophyll Resistance

The corn leafhopper Dalbulus maidis is the main vector of the pathogens that cause corn stunt, a major disease of maize in the Americas. As host resistance is an efficient tool to control diseases, the findings of a previous report showed that some corn hybrids are resistant to D . maidis . In this work, we assessed the probing behavior of D . maidis on susceptible and resistant corn hybrids using EPG (Electrical Penetration Graph) technology. Fifteen-day-old females were monitored for 20 hours, with access to hybrids DK390, DK670, DK79-10, and DK72-10. Hybrids DK390 and DK72-10 showed resistance to D . maidis in phloem, since insects feeding on these hybrids presented more salivation events in phloem without subsequent ingestion, which are seen as failed attempts to ingest. A reduction of the total duration of phloem ingestion was observed, and accordingly of the time spent by insects with access to these hybrids on xylem ingestion. The hybrid DK390 also had mesophyll resistance, seen as less probing time and a higher number of probes of short duration. These findings support and are consistent with previous research, providing useful information to characterize maize hybrids resistant to D . maidis , and so to corn stunt.

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