|Freeman, Thomas - NORTH DAKOTA STATE UNIV|
Submitted to: National Research and Action Plan for Silver Leaf Whitefly
Publication Type: Abstract Only
Publication Acceptance Date: December 21, 1999
Publication Date: N/A
Technical Abstract: Bemisia argentifolii eggs oviposited on artificial membranes of Parafilm M were used to study the role of the egg pedicel on hatch & nymphal development. Females oviposited eggs on membranes. The pedicels of eggs on membranes were exposed to [14C]-inulin. Label uptake per egg was 7.6 dpm or 0.6 nl. Inulin cannot cross biological membrane so it was assumed that inulin resided within pedicel of egg & not within embryo. Eggs were exposed to radiolabeled sodium acetate 48 hr & then held at 95-100% rh until hatch. In three experiments, egg hatch ranged from 91-100% and uptakes of 14C was 339, 349 and 672 dpm/nymph, respectively. Uptake volumes in nl/nymph were 1.6, 0.8 and 1.8, respectively. Thus, eggs use their pedicels to transport water & solutes from the media into developing nymphs. Eggs require water or water vapor for normal embryonic development & egg hatch. Egg laden membranes incubated at 25C for 7-8 days had no hatch at humidities below 95%. At 95-100% rh hatch was 95.0 +/- 5.2%. Thus, whitefly egg hatch is dependent upon water uptake from the host plant either as free water or very humid air. Electron microscopy of mature eggs removed from ovaries revealed that surfaces of the distal portion of the pedicel consisted of a tangled array of fibers. 20-25% of the outer diameter of distal portion of pedicel consisted of fibrous material. Fibers may function as collector and conduit for water vapor and solute into the egg.