|Macedo, Tulio - UNIV OF CALIFORNIA|
|Peterson, Robert K - MONTANA STATE UNIV|
|Weaver, David - MONTANA STATE UNIV|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 3, 2008
Publication Date: February 1, 2009
Citation: Macedo, T.B., Peterson, R.D., Weaver, D.K., Ni, X. 2009. Impact of Diuraphis noxia (Mordvilko) and Rhopalosiphum padi (L.) (Hemiptera: Aphididae) on primary physiology of four near-isogenic wheat lines. Journal of Economic Entomology 102:412-421. Interpretive Summary: Leaf-chlorosis-eliciting Russian wheat aphid and non-chlorosis-eliciting bird cherry-oat aphid feeding on the capacity of primary metabolism was examined using a set of sister wheat lines that confer aphid resistance and susceptibility. Although the impact of aphid feeding on plant growth was assessed extensively on resistant and susceptible wheat cultivars, information about aphid feeding-elicited photosynthetic changes on aphid-resistant and –susceptible sister wheat lines was limited. The bird cherry-oat aphid had a higher reproductive capacity compared to the Russian wheat aphid on all lines except for one that confers Russian wheat aphid tolerance. Although both aphid species negatively affected net photosynthesis, the Russian wheat aphid caused a greater photosynthetic rate reduction than the bird cherry-oat aphid. The photosynthetic pigment and carbohydrate quantification data suggest that the initial net photosynthesis reduction elicited by the two aphid species may not be solely related to the photosynthetic pigment losses.
Technical Abstract: The impact of feeding injury by the Russian wheat aphid, Diuraphis noxia (Mordvilko), and bird cherry oat aphid, Rhopalosiphum padi (L.), (Hemiptera: Aphididae) on susceptible and resistant wheat, Triticum aestivum L., near-isogenic lines ‘Tugela’ (susceptible), Tugela-Dn1 (antibiotic), -Dn2 (tolerant), and -Dn5 (antixenotic) was evaluated by assessing photosynthetic parameters. Photosynthesis and closely related parameters, pigment composition, and non-structural carbohydrates were measured at 1, 3, and 9 d after aphids were introduced on plants maintained under greenhouse conditions. Overall, R. padi had a higher reproductive capacity within a period of 9 d compared to D. noxia on all lines except for Tugela-Dn2. Although the visible injury symptoms associated with aphid injury can be highly species specific, the data indicate that photosynthetic reduction is a common physiological pattern of wheat response to aphid feeding, irrespective of chlorosis elicitation. Although both aphids negatively affected net photosynthesis, D. noxia had a greater impact than R. padi, even when aphid numbers were considerably fewer (100-150 aphids per plant) for D. noxia compared to R. padi (greater than 200 aphids per plant). The photosynthetic pigment and carbohydrate quantification data suggest that the initial net photosynthesis reduction elicited by aphid feeding may not be directly related to the light reaction portion of the photosynthetic pathway via pigment losses. It is also unlikely that source-sink manipulation is the primary cause for the observed short-term inhibition of photosynthesis.