Species diversity, dominance and frequency of leaf-eating Lepidoptera in plum biocenose in Bulgaria

Abstract: The mating disruption technique is one of the most selective methods of controlling Cydia funebrana Tr. and is under development in Bulgaria. In this connection, a pre-study was carried out to follow the dynamics and density of the leaf-eating and fruit-surface damaging lepidopteran larvae in an abandoned plum orchard of mixed varieties in Sofia region. Species belonging to eleven families were found during the eight years of observations. Permanent inhabitants in the plum biocenose were larvae of Gelechiidae, Tortricidae and Geometridae with index of constancy c=100. The next by frequency of occurrence were species of Coleophoridae and Noctuidae (c=87.50), followed by Yponomeutidae (c=75), Lycaenidae (c=50), Lymantriidae and Pieridae (c=25). The rarest were individuals of families Ypsolophidae, Chimabachidae and Lasiocampidae with c=12.50. In 1998 and 2002 the dominant species of all collected lepidopterian larvae was Recurvaria nanella (Denis & Schiffermüller, 1775) and Anarsia lineatella (Zeller, 1839) in 1999. Operophtera brumata (Linnaeus, 1758) dominated in complex of external lepidopteran larvae in 2000 and 2005, Neusphaleroptera nubilana (Hübner, 1799) in 2003, Hedia nubiferana (Haworth, 1811) in 2006 and Argyresthia spp. in 2007. Specimens belonging to 35 genera and 47 species were identified altogether. In spite of very rich biodiversity, the density of leaf-eating and fruit-surface damaging lepidopteran larvae was aboveeconomical threshold only during three of the eight years of investigation, so we consider it possible to develop plant protection programs for biological production of plum fruits in West Bulgaria.