Phyllonorycter blancardella (Fabricius)

Taxonomic placing: Insecta, Holometabola, Lepidoptera, Gracillariidae

Common name: Spotted tentiform leafminer.

Geographical distribution: Europe, east to Ukraine, Middle East and North America.

Morphology: Larva about 4-6 mm long, very flat, young stages legless, elder stages with legs, body yellow-green with a brown head. Prior to pupating the larvae become more yellow. Adult 4 mm long, brown-yellow, forewings reddish with white areas or stripes, heavily fringed. Hindwings narrow with wide fringes.

Host plants: Apple, pear, quince.

Life history: The adults emerge in spring from their diapause sites in fallen leaves. They mate and lay eggs (about 50/female) on the lower side of young host leaves. The hatching larvae (caterpillars) burrow therein, their frass being in the central area of the oval swollen mine, amongst silken threads. They pupate within their mines, even in shed leaves. The pest raises 4-5 annual generations that may partially overlap. The mines attain the form of a lower surface tent-likew form mine, as the epidermis has some folds.

Economic damage: Heavy infestations reduce the photosynthetic capability of the leaves, disrupting growth regulation and the ripening processes. This may be followed by leaf drop (thus increasing fruit exposure to direct sunlight), stunting and premature fruit ripening, reduced fruit quality and quantity, and diminished fruit setting in the following season.

Management:

Monitoring: Examining lower leaf surfaces for the presence of mines. Control measures should be considered after finding 1-2 mines/leaf. Sex pheromone traps are used for pest monitoring in South America, the Middle East, North Africa and Europe.

Horticultural methods: Healthy trees, well supplied with water and nutrients can better tolerate infestation. Destruction of dropped leaves by raking and burning in the autumn may reduce overwintering pest populations.

Chemical control: The pest has become resistance to organophosphate and pyrethroids, and only IGRs are now recommended.

Biological control: In North America the pest is attacked by many species of hymenopterous parasitoids belonging to the families Aphelinidae, Braconidae, Chalcidae, Eulophidae, Ichneumonidae, Pteromalidae and Scelionidae. The most prevalent species were the braconid Pholetesor ornigis (Weed) and the eulophid Sympiesis marylandensis Girault. Eleven parasitoids were collected in Egypt.

References

Bishop, S.D. (and 6 co-authors) 2001. Hymenopterous parasites associated with Phyllonorycter blancardella (Lepidoptera: Gracillariidae) in Nova Scotia and Quebec. Phytoprotection 82: 65–71.

Gagne, R.S. and Barrett, B.A. 1994. Seasonal occurrence and density of Phyllonorycter spp. (Lepidoptera: Gracillariidae) and major parasitoids in Missouri apple orchards. Environmental Entomology 23: 198-207.

Morsi, G. A. 2004. Differential population of the spotted tentiform leafminer, Phyllonorycter (Lithocolletis) blancardella (Fabricius) (Lepidoptera: Gracillariidae) and its parasitoids in Middle Egypt. Egyptian Journal of Biological Pest Control 14: 53-57.

Plaut, H. N. 1975, Overwintering in Israel of Lithocolletis blancardella Fabricius (Lepidoptera, Gracillariidae) and some of its parasites (Hymenoptera, Eulophidae) on apple. Alon Hanotea 29: 525-529 (in Hebrew with an English summary).

Pree, D.J., Marshall, D.B. and Archibald, D.E. 1986. Resistance to pyrethroid insecticides in the spotted tentiform leafminer, Phyllonorycter blancardella in southern Ontario. Journal of Economic Entomology 79: 318-322.

Website: http://mothphotographersgroup.msstate.edu/species.php?hodges=0740