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Melanism and disease resistance in insects
Author(s) -
Wilson Kenneth,
Cotter Sheena C.,
Reeson Andrew F.,
Pell Judith K.
Publication year - 2001
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.2001.00279.x
Subject(s) - melanism , biology , larva , pest analysis , beauveria bassiana , resistance (ecology) , zoology , botany , ecology , biological pest control
There is growing evidence that insects in high‐density populations invest relatively more in pathogen resistance than those in low‐density populations (i.e. density‐dependent prophylaxis). Such increases in resistance are often accompanied by cuticular melanism, which is characteristic of the high‐density form of many phase polyphenic insects. Both melanism and pathogen resistance involve the prophenoloxidase enzyme system. In this paper the link between resistance, melanism and phenoloxidase activity is examined in Spodoptera larvae. In S. exempta , cuticular melanism was positively correlated with phenoloxidase activity in the cuticle, haemolymph and midgut. Melanic S. exempta larvae were found to melanize a greater proportion of eggs of the ectoparasitoid Euplectrus laphygmae than non‐melanic larvae, and melanic S. littoralis were more resistant to the entomopathogenic fungus Beauveria bassiana (in S. exempta the association between melanism and fungal resistance was non‐signficant). These results strengthen the link between melanism and disease resistance and implicate the involvement of phenoloxidase.