1. 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

2. Introduction Hysteroneura setaria Schizaphis graminum Sipha flava
Aphid species recorded co-infesting with M. sacchari
on either sorghum or johnsongrass:
H. setaria
S. maydis
Hysteroneura setaria
Schizaphis graminum
Sipha flava
Sipha maydis
Rhopalosiphum maidis
Rhopalosiphum padi

3. 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 (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

4. Aphid treatment Developmental time (days)
Developmental times for SCA and GB on P8500,
both alone and together (GB+ and SCA+) a b c
Developmental time (days) c
Aphid treatment

5. Aphid treatment Developmental time (days)
Developmental times for SCA and GB on KS116B,
both alone and together (GB+ and SCA+) a ab b ab
Developmental time (days)
Aphid treatment

6. Nymphal survival (%) 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

7. Nymphal survival (%) Aphid treatment
Nymphal survival for SCA and GB on KS 116B,
both alone and together (GB+ and SCA+)
Nymphal survival (%) a b ab b
Aphid treatment

8. Relative reproductive rates of SCA & GB at (23 °C)
infesting P8500 either alone or together (GB+ and SCA+)
Time (days)
GB benefits from SCA, SCA unaffected

9. 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

10. Life tables for SCA and GB infesting
plants either alone or together (GB+ and SCA+)
Cultivar determines commensalism or amensalism
(facilitation or interference)

11. Nymphal survival (%) Aphid treatment
Nymphal survival for SCA and BCOA on P8500 and
PI , both alone and together (GB+ and SCA+) ab
Nymphal survival (%)
Aphid treatment

12. Aphid treatment Developmentlal time (days)
Developmental time for SCA and GB on P8500 and
PI , both alone and together (BCOA+ and SCA+) a a ab b a a a b
Developmentlal time (days)
Aphid treatment

13. 12-day fecundity (no. nymphs)
Reproductive performance of SCA and GB on P8500 and
PI , both alone and together (BCOA+ and SCA+) a b a
12-day fecundity (no. nymphs) b c d c d
Aphid treatment

14. 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