Can aphids extract a high percentage of photosynthate from a plant?

Question

considering that aphids are herbivores that reproduce asexually under good food conditions.

Answer 1

Each of the following 4 paragraphs comes from each of the 4 different websites below:

The crop is plagued by the cotton aphid, Aphisgossypii, which stunts the growth of plants and removes photosynthate and contaminates the lint with its sugary excretions (honeydew).

Photosynthate destined for seed production and plant growth is thus diverted into energy for insect growth.  Aphids reproduce using a form of asexual reproduction called parthenogenesis where only females are present, giving birth to live young (up to 12 per day).  Under optimal conditions these new born nymphs mature into a reproducing adult within as little as five days.  This article will focus on the direct damage caused by soybean aphids, Aphis glycines Matsumura, in the North Central Region.  

Black margined aphids feed on the underside of leaves on major leaflet veins while yellow pecan aphids feed on the network of small veins located throughout the leaf. They damage pecan trees by extracting large amounts of photosynthate and water from leaves, which impairs the growth of both shoots and roots. They also secrete large amounts of honeydew on to leaves, and the sooty mold that grows on the honeydew can reduce photosynthetic efficiency.

In years of high nut set, photosynthates (plant energy) might become limiting. Photosynthate loss from high yellow aphid populations in these years can reduce quality. A host-specific control measure (one which affects only aphids) like a beneficial-friendly insecticide could be used to improve quality under such conditions.