title: Grasshopper crop and midgut extract effects on plants: an example of reward feedback.
abstract: Acid extracts and a resultant fraction from solid-phase extraction (SPE) of Romalea guttata crop and midgut tissues induce sorghum (Sorghum bicolor var. Rio) coleoptile growth in 24-h incubations an average of 49% above untreated controls. When combined with plant auxin, indole-3-acetic acid (IAA), the SPE fraction shows a synergistic reaction, yielding increases in coleoptile growth that average 295% above untreated controls and 8% above IAA standards. The interaction lowered the point of maximum sensitivity of IAA 3 orders of magnitude, resulting in a new IAA physiological set point at 10(-7) g/ml. This synergism suggests that contents in animal regurgitants making their way into plant tissue during feeding may produce a positive feedback in plant growth and development following herbivory. Such a process, also known as reward feedback, may exert major controls on ecosystem-level relationships in nature.
authors.affiliation: Department of Entomology and Institute of Ecology, University of Georgia, Athens, GA 30602, USA.
authors.forename: M I
authors.initials: MI
authors.lastname: Dyer
authors.forename: A M
authors.initials: AM
authors.lastname: Moon
authors.forename: M R
authors.initials: MR
authors.lastname: Brown
authors.forename: D A
authors.initials: DA
authors.lastname: Crossley