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Absence of food‐aversion learning by a polyphagous scarab, Popillia japonica , following intoxication by geranium, Pelargonium × hortorum
Author(s) -
Potter Daniel A.,
Held David W.
Publication year - 1999
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1046/j.1570-7458.1999.00468.x
Subject(s) - geranium , geraniaceae , biology , popillia , fecundity , japonica , botany , japanese beetle , herbivore , poinsettia , horticulture , ornamental plant , population , demography , inflorescence , sociology , bract , cultivar
It is commonly held that food‐aversion learning should be more prevalent in polyphagous herbivores than in specialists. We tested the ability of Popillia japonica , a polyphagous scarab, to learn avoidance of a palatable but illness‐inducing plant. Beetles that feed on flowers of geranium, Pelargonium × hortorum , became paralyzed, although most recovered within 24 h. In choice tests, naive beetles strongly preferred geranium petals over leaves of linden, Tilia cordata , a highly suitable host. Experienced beetles maintained this preference although it resulted in repeated bouts of paralysis. Fecundity was >10 times higher for beetles fed linden foliage for 2 wk than for those fed only geranium. Nevertheless, when a surplus of both foods was provided, the beetles fed mainly on geranium, resulting in greatly reduced fecundity. These results contradict the view that generalists should show propensity for food‐aversion learning. Indeed, in this case, P. japonica continued to prefer the toxic plant, compromising its fitness.