Oviposition by herbivorous insects on spider webs as an anti-predation defence.
Nafus D., Schreiner I.
Author Affiliation: Agricultural Experiment Station, College of Agriculture and Life Sciences, University of Guam, Mangilao, Guam 96923, USA.
Ecological Entomology 16 : 513-517
Abstract : The distribution of eggs of the noctuids Penicillaria jocosatrix, Achaea serva and Dysgonia absentimacula [Parallelia absentimacula] and the geometrid Anisodes illepidaria on food plants and non-plant structures was studied in Guam during 1986, 1988 and 1989. Anisodes illepidaria and P. jocosatrix were found on mangoes, Achaea serva on Achras zapota [sapodillas] and P. absentimacula on Phyllanthus acidus. Most of the eggs of Anisodes illepidaria and Achaea serva (90.7 and 80.9%, resp.) were found on spider webs near new leaves, while the other 2 species laid 20% of their eggs on spider webs. On spider webs, 28% of eggs of A. serva were parasitized by Telenomus sp. Of eggs of P. absentimacula on leaves, 5% were parasitized by a trichogrammatid, compared to 10% of those on webs. No parasitized eggs of A. illepidaria or P. jocosatrix were found. When eggs of A. illepidaria were exposed to foraging workers of Pheidole megacephala on mango branches, workers removed more eggs from leaves than from webs. The fate of eggs of A. illepidaria was monitored on webs and leaves. After 48 h, 3 eggs on the leaves had hatched and 25 had disappeared, while on the webs, 44 eggs had hatched and 12 had disappeared.