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This research study explores the effects of Melanaphis sacchari on the performance of other aphid species on different sorghum cultivars. Results show that M. sacchari can either improve or diminish the performance of co-infesting aphids depending on the cultivar. Effective resistance to M. sacchari is crucial in countering this facilitation.
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Cultivar-dependent facilitation of other aphids by M. sacchari J.P. Michaud Kansas State University Sorghum – Sugarcane Aphid Research Exchange Meeting Dallas, TX January 3 – 4, 2017
Introduction Aphid species recorded co-infesting with M. sacchari on either sorghum or johnsongrass: H. setaria S. maydis Hysteroneurasetaria Schizaphisgraminum Siphaflava Siphamaydis Rhopalosiphummaidis Rhopalosiphumpadi
Materials & Methods • We reared SCA + GB (+ BCOA), alone and together, on pairs of sorghum cultivars • Either: 10 GB, 10 SCA, or 5 GB + 5 SCA - all 1st instars (< 12 h old) • P8500 vs KS116B (SCA + GB) • P8500 vs PI 550610 (SCA + BCOA) • Last aphid to molt to adult left to reproduce on the same plant • All life history data recorded daily - survival, developmental time, reproduction
Developmental times for SCA and GB on P8500, both alone and together (GB+ and SCA+) a b c c Developmental time (days) Aphid treatment
Developmental times for SCA and GB on KS116B, both alone and together (GB+ and SCA+) a ab b ab Developmental time (days) Aphid treatment
Nymphal survival for SCA and GB on P8500, both alone and together (GB+ and SCA+) a a ab b Nymphal survival (%) Aphid treatment
Nymphal survival for SCA and GB on KS 116B, both alone and together (GB+ and SCA+) Nymphal survival (%) a ab b b Aphid treatment
Relative reproductive rates of SCA & GB at (23 °C) infestingP8500 either alone or together (GB+ and SCA+) Time (days) GB benefits from SCA, SCA unaffected
Relative reproductive rates of SCA vs GB at (23 °C) infesting KS 116B either alone or together (GB+ and SCA+) Time (days) GB disadvantaged by SCA, SCA unaffected
Life tables for SCA and GB infesting plants either alone or together (GB+ and SCA+) Cultivar determines commensalism or amensalism (facilitation or interference)
Nymphal survival for SCA and BCOA on P8500 and PI 550610, both alone and together (GB+ and SCA+) ab Nymphal survival (%) Aphid treatment
Developmental time for SCA and GB on P8500 and PI 550610, both alone and together (BCOA+ and SCA+) a a ab b a a a b Developmentlal time (days) Aphid treatment
Reproductive performance of SCA and GB on P8500 and PI 550610, both alone and together (BCOA+ and SCA+) a b a 12-day fecundity (no. nymphs) b c c d d Aphid treatment
Key Learnings Greenbug: SCA improved performance of GB on one variety and diminished it on another, while SCA was unaffected Bird-cherry oat aphid: SCA improved performance of BCOA on both varieties, with SCA performance diminished by BCOA on both, but more so on the less suitable one SCA has the ability to improve the suitability of susceptible sorghums for other aphids, but effects vary with the identity of the co-infesting aphid and the cultivar of the host plant Effective resistance to SCA should counter or eliminate this facilitation of other aphid species