Back to Search Start Over

Variation in Eastern Cottonwood (Populus deltoides Bartr.) Phloem Sap Content Caused by Leaf Development May Affect Feeding Site Selection Behavior of the Aphid, Chaitophorous populicola Thomas (Homoptera: Aphididae)

Authors :
Georgianna G. Gould
Peggy Rifleman
Clive G. Jones
Antonio Perez
James S. Coleman
Source :
Environmental Entomology. 36:1212-1225
Publication Year :
2007
Publisher :
Oxford University Press (OUP), 2007.

Abstract

Apterous populations of Chaitophorous populicola Thomas (Homoptera: Aphididae) appear to track Eastern cottonwood (Populus deltoides Bartr.) leaf development. Few aphids occur on mature leaves. Marked individual aphids on leaves of different developmental stages were observed through a period of new leaf initiation. Nymph and adult C. populicola frequently track leaf development by moving up to younger leaves. A comparison of phloem sap constituents and leaf toughness among leaf developmental stages revealed some differences that could be used by C. populicola to determine leaf age. Phloem sap exudates, collected from P. deltoides leaves of different developmental stages, were analyzed by high-performance liquid chromatography for free amino acids and the phenolic glycoside salicin. Sucrose concentration in exudates, indicative of phloem sap exudation rate, was uniform among leaf stages. Of 20 amino acids examined, only aspartic acid and γ-amino-n-butyric acid (GABA) concentrations differed significantly between leaf stages. Forward stepwise discriminant function analysis showed that seven of the amino acids analyzed are useful for classifying leaf maturity groupings. Aphid-infested cottonwoods had lower cystine concentrations in phloem sap than aphid-free plants. Salicin concentration was significantly higher in new leaves. Leaf toughness was assessed by lignin density and distance measurements in petiole cross-sections. Rapidly expanding leaves had significantly less lignification and new leaves had shorter distances to the vascular bundles than senescent leaves. These physiological and phytochemical differences among P. deltoides leaf developmental stages may contribute to the leaf stage selection patterns exhibited by the aphid, C. populicola.

Details

ISSN :
0046225X
Volume :
36
Database :
OpenAIRE
Journal :
Environmental Entomology
Accession number :
edsair.doi...........5acd5d1f13a75f3f8fab7049aef04b24
Full Text :
https://doi.org/10.1603/0046-225x(2007)36[1212:viecpd]2.0.co;2