Biology of Monochamus galloprovincialis (Coleoptera, Cerambycidae) in the Pine Wilt Disease Affected Zone, Southern Portugal

The biology of Monochamus galloprovincialis, which is the vector of the pathogenic nematode Bursaphelenchus xylophilus, was studied in the pine wilt disease-affected zone south of the Tejo River, Portugal. Insects required ten to thirteen months to develop and had a single generation per year. The emergence pattern during 2001 to 2004 occurred from May to September with a peak in July, being consistent with the captures of attractive traps (flight curve). Emergencies occurred slightly earlier for males than for females, with a global sex ratio of 0.48. Females laid eggs on trap-trees from May to August and the young larvae had an extremely fast development before tunnelling into the xylem, where they passed the winter. The number of larval instars could not be defined by the frequency distribution of head-capsule width measurements. Developmental success and adult dimensions differed between tree sections, being higher for the trunk. Mortality was generally low for all developmental instars and the within log generation survivorship from egg to adult was 53%. The most important identified mortality agents were the fungi Beauveria bassiana and the parasitic wasp Cyanopterus flavator. Results are discussed in view of the current strategies to control the insect and the possible existence of a winter dormancy affecting the insect's larvae.