Leaf Burial by the Earthworm, Lumbricus terrestris (Oligochaeta: Lumbricidae), as a Major Factor in the Population Dynamics of Phyllonorycter blancardella (Lepidoptera: Gracillariidae) and Its Parasites

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Abstract
Leaf burial by the earthworm, Lumbricus terrestris L., is a significant mortality factor for the spotted tentiform leafminer (STLM), Phyllonorycter blancardella (F.), and its braconid parasites, Pholetesor ornigis (Weed) and Pholetesor pedias (Nixon). In apple orchards with high earthworm densities, and in years with relatively warm springs, P. blancardella emerges before all leaves are buried by earthworms. In years with cool springs, STLM development is prolonged and almost all leaves are buried before STLM emergence. In both cases, however, braconid parasites of STLM that overwinter in leaves do not emerge until most leaves have been buried, and, hence, suffer a high mortality. In another orchard with very low earthworm densities, leaf burial was negligible and not a significant mortality factor for STLM or its parasites.