Externally- Feeding Lepidopteran Complex on Untreated Apple Trees – Species Composition, Domination and Ocurrence

The study was conducted to determine species composition, frequency of occurrence and domination of externally- feeding Lepidoptera on untreated apple trees in West Bulgaria. The aim was to estimate specific level of risk of lepidopteran pests outbreaks when organic production of apples is intended to produce. As a result sixty-four moths were identified to feed on buds, flowers, leaves and on the surfaces of apple fruits during sixteen years observations. The group of euconstant (31.3% and constant species 17.2% comprised almost half of the established lepidopteran complex. The other half of the complex consisted mainly of subconstans – 43.8% and the smallest group was this of accessory species – 7.8%. Almost half of the eucostants – 45.0% belonged to family Tortricidae, 20.0% to Geometridae, 15.0% to Noctuidae, 10.0% to Gelechiidae, 5.0% to Ypsolophidae, 5.0% to Coleophoridae. The only one species – Hedya nubiferana Haworth was eudominant, dominants were two pests – Recurvaria nanella Denis and Schiffermьller and Spilonota ocellana Denis and Schiffermьller, subdominants for the whole period of observations were three – Pandemis heparana Denis and Schiffermьller, Operophtera brumata Linnaeus and Recurvaria leucatella Clerck, recedents eleven – Acleris rhombana Denis and Schiffermьller, Archips rosana Linnaeus, Pandemis cerasana Hьbner, Erannis defoliaria Clerck, Pasiphila rectangulata Linnaeus, Alsophila aescularia Denis and Schiffermьller, Cosmia trapezina Linnaeus, Orthosia cerasi Fabricius, Coleophora hemerobiella Scopoli, Coleophora coracipennella Hьbner, Malacosoma neustria Linnaeus, and forty-seven lepidopteran species were subrecedents. The number of species making 70-80% of the complex varied from three to eleven comprising twentythree species altogether or 37.09% of all identified Lepidoptera. These are the insects against which selective insecticides have to be tested and applied in the established highest effective dose against pest of this gild in spring, when it is supposed that threshold of injury would be rich. New contribution for Bulgarian apple entomofauna were found specimens of the species Cilix glaucata, Scopoli 1763 Drepanidae and Macrothylacia rubi, Linnaeus, 1758 Lasiocampidae on apple trees.