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Pest Status and Background
Chapter 20
Phyllonorycter blancardella (F.), Spotted
Tentiform Leafminer (Lepidoptera:
Gracillariidae)
J.E. LAING
The spotted tentiform leafminer (STLM). Phyllonorycler blancardella (F.). is an indirect
pest of apple in eastern Canada and the United States. This species probably
entered North America from Europe early in the 1900s. Severe infestations (> 20 mines
per leaf) may cause early leaf drop. stunting of terminal growth. premature fruit
ripening, and fruit drop with a resultant decrease in yield and reduction of fruit set the
year following the infestation (Pottinger & LeRoux 1971. Johnson 1975). There are three
generations of the leafminer per year throughout its range in North America. The
leafminer overwinters as a pupa. emerges in May. and begins to oviposit first-generation
eggs. Adults of the first generation are present in orchards from mid-June through July.
Second-generation adults appear in August (Johnson 1975. Laing 1977).
Although many species of parasitoids have been recorded from STLM (Pottinger &
Le Roux 1971. Johnson el al. 1978). this species is able to reach damaging levels in some
orchards each year by the third or overwintering generation. Because of the cryptic
feeding habits of the larvae. chemical controls must be either systemic or timed to
coincide with adult emergence. The latter has been facilitated by the synthesis of a sex
attractant for STLM (Roelofs el al. 1977) and the development of heat unit requirements
above a threshold of approximately 7°C for emergence of the adults (Johnson el 01.
1979). Although individual growers may obtain good control of STLM at times. reinvasion
of commercial orchards likely occurs from hedgerow and abandoned or poorly
maintained orchards.
The following parasitoids have been reported from STLM in Ontario and Quebec
(Pottinger & LeRoux 1971. Johnson el al. 1978):
Braconidae Apanteles ornigis Weed
Eulophidae Sympiesis marylandensis Girault
Sympiesis bimaculatipennis Girault
Sympiesis sericeicornis (Nees)
Sympiesis conica (Provancher)
Pnigalio maculipes (Crawford)
Pnigalio flavipes (Ashmead)
Pnigalio uroplatae (Howard)
Chrysocharis cuspidogaster (Yosh.)
Chrysocharis Iricinclus Ashm.
Chrysocharis laricinellae (Ratz.)
Tetrastichus sp.
Cirrospilus cinclilhorax (Girault)
Zagrammosoma mullilinealum (Ashmead)
Horismenus Jraternus (Fitch)
Eupelmidae Eupelmella vesicularis (Retzius)
The most abundant parasitoids of STLM are the braconid Apanteles ornigis Weed in
the first and third generations. and the chalcids Sympiesis marylandensis Gir. and S.
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