The phloem-specific feeding behavior of Green peach aphids (GPA), using their incredibly slender stylets, help them to feed continuously from a single sieve element for an extended period of time. The Arabidopsis-Myzus persicae (Sülzer) (HEMIPTERA: APHIDIDAE) model helped us to characterize the response of GPA on Arabidopsis thaliana. We had previously demonstrated that a recessive mutation in the SSI2 gene results in heightened resistance to GPA in the ssi2 mutant plant. Microarray studies identified a gene At5g14180, which in comparison to the wild type (WT) plant is expressed at elevated levels in leaves of the ssi2 mutant and in GPA infested wild type plants. At5g14180 encodes a protein with homology to lipases. Mutations in At5g14180 resulting from the insertion of T-DNA within the gene impacted host plant resistance to GPA. No-choice test (antibiosis) indicated that there is an increased number of GPA on the At5g14180 mutant as compared to WT plants. However, choice test (antixenosis) showed comparable numbers of GPAs on the mutant and WT plants. Comparison of GPA feeding behavior on WT versus the lipase mutant indicated that there was no significant difference in the total duration of the sieve element phase (SEP) spent by GPA on lipid mutant and WT plant, suggesting that the mutation does not deter aphid feeding. Since, both SSI2 and At5g14180 encode proteins involved in lipid metabolism, and mutations in At5g14180 attenuate the ssi2-conferred heightened resistance to GPA, we suggest that a lipid or lipid-derived product is involved in antibiosis against GPA.