Rl. Hill et al., Biology and host range of Phytomyza vitalbae and its establishment for thebiological control of Clematis vitalba in New Zealand, BR EDUC R J, 27(4), 2001, pp. 459-473
Phytomyza vitalbae Kaltenbach (Diptera: Agromyzidae) creates mines in leave
s of Clematis vitalba, a significant environmental weed in New Zealand. Stu
dies in Europe found that most leaves had one mine, but some had many; heav
y mining deformed leaves and reduced photosynthetic area.; P. vitalbae was
multi-voltine; fecundity averaged 521 eggs per female; and larval parasitis
m was high. Together, these biological characteristics suggested it had the
capacity to produce large populations in the absence of parasitism. P. vit
albae has been recorded on other Clematis species in Europe, and experiment
al determination of host range confirmed this species was narrowly oligopha
gous, but posed no significant risk to New Zealand native plants. Results s
uggested mines might be produced in some exotic Clematis species growing in
New Zealand, but only where flies fed on C. vitalba before ovipositing. P.
vitalbae was released from quarantine in New Zealand in 1996. It is consid
ered to be established at 20 of the 29 release sites, and populations have
grown rapidly at those sites. The Xy spread 5 km within 15 months at one si
te. Three parasitoids have been reared from P. vitalbae mines since its rel
ease in New Zealand, but it is uncertain whether parasitism will adversely
affect leafminer populations.