Hort symposium


New IPM strategies from across the pond


British expert describes alternatives being developed to combat pome fruit pests. By Susan McIver


E


xploiting earwigs, disrupting ant- aphid ‘mutualism’ and a newsex pheromone trap for apple leaf


midges and capsid bugs are among new alternative approaches to integrated pestmanagement being developed in theUnitedKingdom. Jerry Cross shared those approaches


with growers attending this year’s Horticultural SymposiuminKelowna. An internationally recognized expert, Cross is leader of the Pest and Pathogen Ecology for Sustainable Crop Management programat EastMalling Research (EMR). EMRis a principal centre in theUK


for basic, strategic and applied horticultural research. In 2012, Cross spent sixweeks on a


study tour of pestmanagement programs in fruit-growing regions near theGreat Lakes, the PacificNorthwest of theUnited States and Canada. During this tour, he spent twoweeks


visiting B.C. fruit growers and research institutes in the Fraser andOkanagan valleys. Aphid pests of apple and pear,with


the exception of thewoolly aphid, have a strongmutualismrelationshipwith the common black ant. The ants obtain honeydewfromthe


aphids andmay also eat the aphids as a source of protein. Benefits to the aphids include


soothing and sanitary effects, direct transportation to better sites and perhapsmost importantly, protection frompredators and parasites. “The antswill bite the legs of


predators and squirt formic acid on them,” Cross said. The use of sticky bands around tree


trunks to prevent ants reaching the aphids, clearly demonstrated that if protection by ants is removed, the


British Columbia FRUIT GROWER • Summer 2013 11


aphids are readily attacked by predators, such as lady beetles, spiders, and hoverflies. Strategies tested to disrupt


mutualisminclude use of sticky bands, provision of an alternate food source (sugar) for the ants,management of grass root aphids to attract ants away fromfruit trees and establishment of competitors to the black ant such as the red ant. Another useful strategy is autumn


sprays of aphicides. Common European earwigs are now


being viewed favourably, because of their capacity to consume large quantities of pear psylla andwoolly aphids. When earwigs are abundant in


orchards, pear psylla andwoolly aphids are not a problem. Formerly, earwigswere seen as pests


themselves, because they can damage trees and ripening fruit, especially soft fruits. “Itwas previously thought thatmost


insecticideswere harmless to earwigs, but that iswrong. Many common insecticides used in Europe have deleterious long termeffects,” Cross said. Cross added thatwork is needed to


clarify the factors in addition to insecticides that are responsible for the large variation observed in earwig populations in different orchards.


Apple leafmidges are


important pests especially in nurseries and newly established orchards in Europe, Canada, theUS andNew Zealand. Themidges have proven difficult to


controlwith insecticides. However, some success has been


achievedwith natural enemies such as parasitic platygastridwasps. Recently, sex pheromones for several


gallmidge pests of apples and pears and for capsid bugs have been discovered. When used in traps, these


pheromones can be used for pest monitoring and timing sprays. Thework on ant-aphidmutualism


was done by PhDstudent at EMR CsabaNagy, thework on earwigs by Cross’ colleagueDr.Michelle Fountain and that on the apple leafmidge pheromone jointlywith Prof.David Hall. Funding for theworkwas through variousHorticulture LINKprojects which are funded jointly by the UK government and UK horticulture industry, especially the Horticulture Development Company.


Jerry Cross, a featured speaker from East Malling Research in England.


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