More virulent offspring result from hybridization of invasive aphid species, Diuraphis noxia (Hemiptera: Aphididae), with Diuraphis tritici endemic to the United States

Authors: Puterka, Gary

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2016
Publication Date: 3/1/2017
Citation: Puterka, G.J. 2017. More virulent offspring result from hybridization of invasive aphid species, Diuraphis noxia (Hemiptera: Aphididae), with Diuraphis tritici endemic to the United States. Journal of Economic Entomology. 110(2):731-738.

Interpretive Summary: The Russian wheat aphid (RWA) is a global pest of small grains that invaded the United States in 1986. Prior to its invasion, a closely related aphid, western wheat aphid, was native to the USA and infests wild grasses and wheat. Both of these aphids have been found to infest the same wild grasses during the time they produce males and females that mate and lay eggs to pass the winter. In the spring, both species give live birth to nymphs and do not need to mate. We conducted mating studies between these two species to determine if they could hybridize. A colony was produced from one hybrid progeny that resulted. This colony was tested for its ability to damage a wide range of wheat and barley varieties in comparison to both parents. The hybrid progeny had lower fitness in that it offspring grew slower to adult and reproduced less than either of its parents. However, damage to sixteen wheat and barley lines 21 days after infestation found the hybrid colony caused equivalent damage to wheat but higher damage to barley than its parents.

Technical Abstract: The Russian wheat aphid (RWA), Diuraphis noxia, invaded the United States in 1986 and soon became a significant pest of wheat. D. tritici was native to the USA and firmly established on wild grasses before the arrival of RWA. Both species are known to co-infest the same grass hosts during the time they enter the sexual phase in the fall, mate, and produce overwintering eggs. Therefore, we induced males and females under greenhouse conditions in the fall and conducted crossing studies in the laboratory to determine if these two species interbred and produced viable offspring. The fitness and virulence to RWA resistant wheat and barley entries were also compared between the hybrid progeny and both parents. D. tritici produced males and females in early October while only D. noxia biotype RWA8 produced enough oviparae to conduct crossing experiments. No males occurred in the D. noxia colony making it only possible to crossbreed D. tritici males with RWA8 oviparae and to inbreed D. tritici. No difference in mean egg production/female (2.0 – 2.5) or percent egg hatch (23.1 – 27.0%) was found between crosses. However, progeny survival after hatch for D. tritici inbreds (33.3%) was much higher than the D. tritici x D. noxia crosses (0.25%). Only one hybrid survived to reproductive adult. Intrinsic rate of increase (rm) indicated the hybrid (0.18) was less fit than both parents (0.24-0.29). The hybrid line produced damage ratings to the 16 cereal entries similar to D. tritici but has more virulent to barely resistance than both parents.