Apple aphid, Aphis spp. (Hemiptera: Aphididae), and predator populations in an apple orchard at the non-bearing stage: The impact of ground cover and cultivar

Abstract

Apple aphid, Aphis spp. (Hemiptera: Aphididae), and predator populations in an apple orchard at the non-bearing stage: The impact of ground cover and cultivar BRUNO Abstract.A two-year field experiment was conducted to determine whether a conservation biological control strategy could be applied to enhance the biological control of green apple aphids, Aphis spp., in a high-density and scab-resistant apple orchard at the non-bearing stage. The natural occurrence of aphid predators and their impact on aphid populations were evaluated in 2005. The impact of predation on aphid densities was evaluated by comparing a predator exclusion treatment with a control. In 2006, the possibility to enhance predator abundance/performance and aphid biological control with a flowering ground cover was tested: trees were grown either with a flowering ground cover of phacelia, Phacelia tanacetifolia Bentham, and buckwheat, Fagopyrum esculentum Moench, or with a conventional ground cover of mixed Poaceae species. In 2006, it was also determined whether aphid densities differ between Liberty and Topaz, 2 scab-resistant cultivars. Results indicate that the predatory arthropod community was dominated by Coccinellidae, Cecidomyiidae, and various spider species. The ladybird community was dominated by the exotic species Harmonia axyridis Pallas, and the abundance of this species was correlated with aphid density. Naturally occurring predators had little impact on aphid abundance, although the proportion of trees with aphid colonies was greater in the predator exclusion treatment on two consecutive dates in 2005. Ground cover types had no impact on aphid densities. The oviposition response of Cecidomyiidae to aphid density was greater in Liberty trees with flowering ground cover than with the conventional ground cover. Conversely, the response of ladybird adults to aphid density was more important in Topaz trees with the conventional ground cover than with the flowering ground cover. Finally, no difference occurred in aphid abundance between Liberty and Topaz trees. Those results are discussed from a biological control and ecological point of view.

Role of ants in structuring the aphid community on apple

“…Aphis pomi completes its whole life cycle on apple. In a survey during the experiment, A. pomi and the spirea aphid, A. spiraecola Patch, were found together in our apple orchards, as happens in North America (Fréchette et al, 2008) and some European countries (Andreev et al, 2007). These two species are very similar and hardly distinguishable in the field, so they will be referred to hereafter as green aphids Aphis spp.…”

Aphis pomi and Aphis spiraecola (Hemiptera: Sternorrhyncha: Aphididae) in Europe - new information on their distribution, molecular and morphological peculiarities

“…Their distribution, morphology, life cycles and host specificity have therefore been subjected to intensive study, together with their potential harmfulness and plant protection measures (Grasswitz & Burts, 1995;Tsai & Wang, 2001;Brown et al, 2008;Stoeckli et al, 2008;Frechette et al, 2008;Brown, 2011;Wieczorek et al, 2011;Cao et al, 2012). The apple aphid is monoecious and holocyclic on woody pomoideous hosts, with apterous males (Baker & Turner, 1916;Patch, 1923;Westigard & Madsen, 1964;Karczewska, 1965;Rakauskas & Rupais, 1983).…”

Leucopis annulipes larvae (Diptera: Chamaemyiidae) use a furtive predation strategy within aphid colonies

“…albipuncta eggs are usually laid in group of 2-3 under apple leaves in New Hampshire. As for A. aphidimyza (Kozár et al, 1994;Stewart & Walde, 1997;Brown, 2004;Fréchette et al, 2008), their abundance is highly correlated with aphid density (Tracewski, 1983). In many systems Leucopis spp.…”