Development of citrophilus mealybug (Pseudococcus calceolariae) on grape roots
Pseudococcus calceolariae (Hemiptera Pseudococcidae) is a vector of Grapevine leafrollassociated virus 3 (GLRaV3) the most destructive virus disease affecting New Zealand grapevines Previous studies suggest that P calceolariae can survive on remnant vine roots for at least 12 months and these mealybugs could account for the spread of the disease in replanted vineyards A laboratory assay test was developed to observe the growth of P calceolariae on grape rootstock 3309 Clean root pieces were left on moist filter paper in Petri dishes for a week to encourage new growth before P calceolariae eggs (n15) were inoculated and held at 23C Recordings were made every 34 days of the survival and development from first instar until males emerged as adults and females started oviposition About 50 mortality was recorded during first and second instars and ca 30 developed into adult stages The development periods from first instar to adult males and females were 441 1 (n16) and 454 1 (n22) respectively This methodology is being developed to assess the relative resistance of grapevine rootstocks effects of contact insecticides and to understand GLRaV3 transmission from roots