Bioecology of the parasitism of Billaea rhynchophorae (Blanchard, 1937) (Diptera: Tachinidae) in Rhynchophorus palmarum (L., 1758) (Coleoptera: Curculionidae) in Brazil

Abstract

We investigated bioecological aspects of Rhynchophorus palmarum parasitism by Billaea rhynchophorae under field and laboratory conditions. In oil palm plantations, eleven species of spontaneous flowering plants were also collected and identified. In the laboratory, the effect of food resources on some parasitoid parameters was also assessed. The mean parasitism rate in the field was higher than 60%, but no significant correlation existed between the environmental variables and the parameters evaluated. Spontaneous flowering plants identified were Acmella uliginosa (Sw.) Cass., Ageratum conyzoides L., (Asteraceae), Borreria verticillata (L.) G. Mey. (Rubiaceae), Clidemia hirta (L.) D. Don (Melastomataceae), Commelina erecta L. (Commelinaceae), Cuphea racemosa (L.f.) Spreng. (Lythraceae), Ipomoea sp. (Convolvulaceae), Lantana camara L., Stachytarpheta cf. maximiliani Schauer (Verbenaceae), Ludwigia sp. (Onagraceae) and Sauvagesia erecta L. (Ochnaceae). The mean viability of parasitoid pupae from the field was 41.83%, and the mean pupal duration was 45.54 days. Mean parasitoid puparia length, diameter, and weight were 10.61 mm, 4.8 mm, and 0.07 g, respectively. The sex ratio of flies was 0.59, and the mean longevity was 8.61 days. Each female produced an average of 159.79 planidia, with a length of 0.92 mm. Longevity of parasitoids fed with bee pollen, 20% honey, and sugarcane stalks was greater when compared to those fed with Adonidia merrillii flowers, chamomile flowers, and 33% sucrose. However, there was no parasitism or viable planidia when adults were fed with the food resources evaluated until 18 days of age.