Providing sugar sources for ants improves the biological control of Aphis spp. in apple orchards

Manipulated ants: inducing loyalty to sugar feeders with an alkaloid

“…21 However, it is also relevant in cases in which omnipresent ants that are not used in biological control programs contribute to the build-up of aphid or other honeydew-producing pest populations in various crops. [26][27][28][46][47][48][49] If ants become loyal to sugar dispensers via attraction to an added alkaloid, then they likely prefer these to honeydew, give up attending aphids and may even switch to aphid preying 34 rather than aphid protection, ultimately leading to lower aphid populations. Although we realize that morphine is an expensive option to use commercially, other alkaloids with similar effects could serve as a cheaper but viable alternative.…”

“…This approach applies in cases in which ants are used actively to control pests (for example in fruit plantations), thus leaving only the positive effects of the ants 21 . However, it is also relevant in cases in which omnipresent ants that are not used in biological control programs contribute to the build‐up of aphid or other honeydew‐producing pest populations in various crops 26–28,46–49 . If ants become loyal to sugar dispensers via attraction to an added alkaloid, then they likely prefer these to honeydew, give up attending aphids and may even switch to aphid preying 34 rather than aphid protection, ultimately leading to lower aphid populations.…”

Implementing wood ants in biocontrol: Suppression of apple scab and reduced aphid tending

“…A number of studies have successfully tested if feeding with artificial sugar sources can effectively distract ants from attending harmful plant sap feeding homopterans on crop plants, including apples, vine, citrus, olives and pumpkins. 17,[34][35][36][37][38][39][40][41] In these studies carbohydrates have been offered as sucrose solutions, mixed sugar solutions or solutions based on honey, and in various carbohydrate concentrations. All studies led to decreased levels of aphid tending and most studies also detected reduced homopteran abundance on the crop plants.…”

“…In return for the honeydew and to increase productivity, ants protect homopteran partners against their natural enemies, sanitize them by removing their waste products (the honeydew) and transport them to fresh plant tissues 15 . This may lead to increased numbers of sap‐sucking homopterans and may negate the positive effects of ants in agricultural systems 16–19 …”

“…15 This may lead to increased numbers of sap-sucking homopterans and may negate the positive effects of ants in agricultural systems. [16][17][18][19] To counteract the mutualism between ants and their trophobionts, sugar feeding has been employed. If provided with dispensers containing artificial sugar solutions, ants may choose artificial sugar over honeydew and stop attending homopterans.…”