Biology of the Eucalyptus leaf beetle Paropsisterna selmani (Chrysomelidae: Paropsini): a new pest of Eucalyptus species (Myrtaceae) in Ireland

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Abstract

  1. The biology of the Eucalyptus leaf beetle Paropsisterna selmani (de Little) (Chrysomelidae: Paropsini) was assessed in the field and under laboratory conditions. The invasive species, most probably from Tasmania, severely defoliates the new flush foliage of several Eucalyptus species in Ireland.
  2. The adult beetles and larvae both fed on the foliage and caused typical broom-top damage to trees. Adult beetles over-wintered in the soil and emerged in April and laid egg batches of approximately seven eggs on the leaves. Teneral adults were most noticeable in late June and July.
  3. In bioassays, the life cycle took approximately 26 days to complete at 20 °C, and survival rates were approximately 67% when fed on E. parvula. Teneral adults took 13.3 days to initiate egg-laying. Leaf consumption was highest in female larvae, and adult beetles consumed a leaf area of approximately 102 mm2/day.
  4. A mean daily egg-laying rate of 11.4 eggs/female was recorded over a period of 130 days. This egg-laying rate is comparable to other leaf beetles attaining pest status in other Eucalyptus-growing regions.
  5. The biology of Pt. selmani suggests that this will be a significant pest of Eucalyptus species grown for cut-foliage and forestry in Ireland. It also poses a potential threat to eucalypt-growing regions in the U.K. and mainland Europe.

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