Paper Title
Population Abundance Of Woolly Aphid, Eriosoma Lanigerum (Hemiptera: Aphididae) And Parasitism By Aphelinus Mali (Hymenoptera: Aphelinidae) In Apple Orchard In Thimphu Valley, Bhutan

Abstract
This study aimed to investigate the abundance of woolly aphid, Eriosoma lanigerum (Hemiptera: Aphididae) infestation and examine parasitism by natural enemy, endo-parasitoid, Aphelinus mali (Hymenoptera: Aphelinidae) in apple. The monitoring survey was conducted in two apple orchards in Thimphu valley, Bhutan from April-October 2018. Primary data were collected randomly from five trees comprising sample unit of four terminal shoots (approx. 10 cm) each tree. Woolly aphid and natural enemies were enumerated fortnightly. Plant samples along with aphid colonies and mummies were collected and reared. Parasitoids emerged are identified to species. The aphid infestation was observed higher during the growing season (June-September) when tender shoots and plants resource are abundant. The infestation level was significantly different in the two orchards surveyed. An independent sample t-test showed statistical significant difference in the aphid abundance. Results indicated Hongtsho-2 (M=1.40, SD= 0.30) extremely significant difference than Kausumche-3 (M=1.27, SD= 0.38) over growing season t =0.358, P=0.0001. Parasitism by A. mali was detected only two weeks after aphid colonies are already established. There was significant difference in parasitism of 12% and 34% at Hongtsho-2 and Kausumche-3 respectively despite variations in the time of occurrence and commencement. With in-depth management study of natural enemy, A. mali, intensive use of chemicals can be averted with consideration of effective natural biological control of woolly aphid in apple. Keywords - Apple, Conservation, Endo-parasitoid, Pest Management, Woolly Aphid