Aphid specific predators in potato in Belgium.
In summer 2003, aphid specific predators populations were sampled in four potato fields located in Wallonia. Ladybirds, hoverflies and lacewings were the most abundant predators collected. A total of 6 ladybird, 8 syrphid and 2 lacewing species was found. Predator species composition and abundance greatly differed from field to field, while aphids populations were more or less similar with a peak of 3 to 5 aphid/potato leaf in mid-July. All chrysopidae sampled belong to the Chrysoperla kolthoffi (NAVAS) species except 2 specimens of Chrysopa perla L. Episyrphus balteatus DEGEER was the dominant syrphid species. Sphaerophoria scripta L. and Syrphus vitripiennis MEIGEN were subdominant species and 1 or 2 specimens of Melanostoma scalare F., Melanostoma mellinum (L.), Melliscaeva cinctella (ZETTERSTED), Metasyrphus corollae (F.) and Platycheirus albimanus F. were also collected. Coccinella septempunctata (L.) and Propylea quatuordecimpunctata (L.) were the dominant ladybird species. P. 14-punctata was proportionally more abundant in beating samples than with visual inspection samples, indicating that this ladybird is probably more discrete than C. septempunctata and that their populations can be underestimated with only visual inspection. Adalia bipunctata (L.) was also present in nearly all samples, but with lower levels of populations. Coccinella quinquepunctata (L.) and Adalia tenpunctata (L.) were found in small numbers at one occasion. Larvae and adults of Harmonia axyridis PALLAS, the multicoloured Asian beetle introduced in glasshouse for aphid control, were found in 3 fields out of 4, with 1.5 to 6% of ladybirds sampled. This is the first record of H. axyridis in open field in Belgium. As this beetle has been found in numbers at different locations and with different growth stages including larvae and pupae, it is supposed that H. axyridis is adapted to ware potato aphid and able to complete a full life cycle in this crop. As this species is very competitive for exploitation of food resources and aggressive for other predators, they are several questions about the evolution in the future of aphid specific predator biodiversity in ware potato.
Jansen
J P
JP
Agricultural Research Centre, Department of Biological Control and Plant Genetic Research, Zoology Unit, Chemin de Liroux 2, B-5030 Gembloux, Belgium.
Warnier
A M
AM
D000818:Animals; D001042:Aphids / Q000145:classification / Q000502:physiology*; D001530:Belgium; D004175:Diptera / Q000502:physiology; D005843:Geography; D011235:Predatory Behavior; D011198:Solanum tuberosum / Q000469:parasitology*