Halbert, Susan E.

Mowry, Thomas

Undetermined

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Section VLTVectors of Plant PathogensDOES THE TOBACCO APHID HAVE POTENTIAL TO CAUSE DAMAGE TO IDAHOPOTATOES?Susan Halbert and Tom MowryAberdeen R&E Center, P.O. Box AA, Aberdeen, LD 83210As a result of work by RogerBlackman, it is now accepted that the entity which has been knownasthe green peachaphid is really at least threespecies. It was not known if either of thenewly designatedspeciesoccurred in Idaho, or whetherthey had the potential to causedamage to potatoes, Idaho's mostimportant crop. We obtainedpermissionfrom the State Department of Agriculture to work withMyzusnicotianaeBlackman, the tobaccoaphid, to attempt to answer this question.Green peach aphids pose a threat to the potato crop primarily because they transmitpotato leafroilvirus (PLRV). Because PLRV is a persistently transmitted luteovirus, the vector must colonize the cropto be an efficient vector. Additionally, Idaho winters are severe enough that a species capable ofholocyclic overwintering would do better in Idaho than one which is not. The objectives of our researchwere to determine whether the tobacco aphid occurred naturally in Idaho, whether it could transmitPLRV, whether it could colonize potato and whether it was holocyclic.Methods:Trap NurseriesTrap nurseries, including host plants of all the Myzus (Nectarosiphon) spp. reported in NorthAmerica, were planted at Moscow, Parma, Aberdeen and Tetonia. These were observed throughout theseason, and allMyzus found were collected alive, allowed to form colonies, harvested and identified.The trap nursery at Parma was maintained for a second season.Host AcceptanceOne clone of green peach aphids and two clones of tobacco aphids were given access to potato,tobacco and mustard plants in a randomized complete block design with 6 replications. Adults wereallowed to deposit nymphs on the plants for 24 hours, after which the adults were removed and numbersof nymphs were adjusted to five per plant. After 15 days, the aphids were harvested by Berleseextraction and aphids were counted.PLRV TransmissionThe same three clones were given a two day access to Physalisfloridana leaves infected withPLRV. They were then transferred to P. floridana indicator plants for 3 days. The indicator plants wereheld in the greenhouse and observed for symptoms. The experiment was replicated four times, using 20aphids per replicate. Sets of 20 plants infested with green peach aphids directly from the culture and 20uninfested test plants were includedas checks in each replicate.Holocycle ExperimentCultures of the same three clones were kept in a growth chamber maintained at 8 hour days and15°C for 3 months. These were observed periodically for sexualesand eggs.77Results:Trap NurseriesNoMyzus spp. other thanM.persicae were found in trap nurseries. Tobaccowas not colonized.Based on this, we think that M. nicotianae does not occur naturally in Idaho.Host AcceptanceTobacco aphids were able to colonize potato as well as green peach aphids.PLRV TransmissionTobacco aphids transmitted PLRV. Neither clone transmitted the virus as well as the greenpeachaphids, but the clone of green peach aphids we usedwas selected for its high PLRV transmissionefficiency. Transmission ratesof the tobacco aphids fell within the range of other greenpeach aphidswehave tested (Halbert, Castle and Mowry, unpublished data).Holocycle ExperimentThe green peachaphidcloneproduced males, oviparae andeggsand eventually disappeared exceptfor the eggs. This is typical of a holocyclic species. Thoughonemale was found in one of the tobaccoaphidcolonies, therewereno oviparae and no eggs. Theapterous viviparae continued to multiplythroughout the experiment.Conclusions:Tobacco aphids probably do not occur naturally in Idaho. They cancolonize potato and transmitPLRV aswellas the common green peach aphid; however, unless a holocyclic cloneexists andisintroduced, they probably cannotbecome a permanentthreat to the Idaho potato crop.78

Does the Tobacco Aphid have Potential to Cause Damage to Idaho Potatoes?

https://ir.library.oregonstate.edu/downloads/pn89dd203

Does the Tobacco Aphid have Potential to Cause Damage to Idaho Potatoes?

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