Submitted to: Biocontrol
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/2/2005
Publication Date: 12/1/2006
Citation: Spellman, B., Brown, M.W., Mathews, C.R. 2006. Effect of floral and extrafloral resources on predation of aphis spiraecola by harmonia axyridis on apple. Biocontrol Testing. BioControl (2006) 51:715-724 Interpretive Summary: The use of plants that provide flowers or extrafloral nectar as food for insects is being proposed as a sustainable method to increase the amount of biological control. This study was conducted to examine the effects of both flowers and extrafloral food resources under controlled conditions in the greenhouse to see if these food sources would interfere with biological control of aphid by the Asian lady beetle. The presence of buckwheat flowers did had no effect on the rate of biological control of aphids, but the presence of peach extrafloral nectar did reduce the rates of biological control. Although the study was done in highly controlled, small scale conditions for only 4 hours, the reduction in biological control does indicate that providing alternative food may have the undesired result of reducing biological control. These results will be used by other biological control researchers in developing production systems that include biological control aspects.
Technical Abstract: Flowering companion plants and plants producing extrafloral nectar are being proposed to enhance biological control in apple (Malus domestica Borkh.) orchards. This experiment evaluated the impact of floral and extrafloral resources on predation of spirea aphid (Aphis spiraecola) on apple by adult Harmonia axyridis (Pallas) under greenhouse conditions. Predation of spirea aphids was not affected by the presence of flowering buckwheat (Fagopyrum esculentum) as compared with either buckwheat with flowers removed or an uninfested apple shoot. However, there was a significant reduction in predation of spirea aphids on an apple shoot in the presence of a peach shoot with extrafloral nectar glands compared with either a peach shoot of the same cultivar without nectar glands or an uninfested apple shoot. These findings demonstrate that alternative food resources potentially could interfere with rates of biological control and, therefore, need to be carefully evaluated before incorporating in an orchard design. More studies are needed to adequately gauge the net effects of adding floral or extrafloral resources in orchards for conservation biological control.