Location: Fruit and Tree Nut Research
Title: Pecan aphids, part II: feeding biologyAuthor
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Submitted to: Pecan South
Publication Type: Trade Journal Publication Acceptance Date: 5/7/2019 Publication Date: 6/1/2019 Citation: Cottrell, T.E. 2019. Pecan aphids, part II: feeding biology. Pecan South. (52)4: 34-39. Interpretive Summary: Three species of aphids, black pecan aphid (BPA), yellow pecan aphid (YPA) and blackmargined aphid (BMA) attack pecan foliage. The YPA and BMA do not require leaf tissue modification to feed on phloem sap after inserting stylets. In contrast, BPA must enzymatically condition leaf tissue to break down chlorophyll in order to feed on the resulting catabolites of chlorophyll breaking down. Leaf conditioning by BPA requires time and thus a proportion of BPA nymphal population moves to the upper side of the leaf surface to feed. This surface has lower predator abundance than the bottom surface of the leaf and allows the nymphal BPA the time required to elicit leaf chlorosis (chlorophyll breakdown). If a YPA or BMA nymph is disturbed on the bottom leaf surface, it can quickly leave its feeding site and begin feeding anew all within a short period of time. If the BPA moves, it requires an additional 2 to 2.5 day to condition a new area of leaf tissue for feeding. This greatly slows down aphid development exposing it to future predation. Technical Abstract: Three species of aphids, Melanocallis caryaefoliae, Monelliopsis pecanis and Monellia caryella, attack pecan foliage. Monelliopsis pecanis and M. caryella do not require leaf tissue modification to feed on phloem sap after inserting stylets. In contrast, M. caryaefoliae must enzymatically condition leaf tissue to break down chlorophyll in order to feed on the resulting catabolites of chlorophyll breaking down. Leaf conditioning by M. caryaefoliae requires time and thus a proportion of the M. caryaefoliae nymphal population moves to the upper side of the leaf surface to feed. This surface has lower predator abundance than the bottom surface of the leaf and allows nymphal M. caryaefoliae the time required to elicit leaf chlorosis (chlorophyll breakdown). If a M. pecanis or M. caryella nymph is disturbed on the bottom leaf surface, it can quickly leave its feeding site and begin feeding anew all within a short period of time. If a M. caryaefoliae nymph moves, it requires an additional 2 to 2.5 day to condition a new area of leaf tissue for feeding. This greatly slows down aphid development exposing it to future predation. |
