CONTROL TRIALS

• Here we report on field trials (Rey & Espadaler, 2005) that have been applied to a heavily invasive population of Lasius neglectus (Seva, Spain: 41.80N,2.26E) in which ants have been known, and recently reported, to invade houses and gardens from as early as 1985. 73 properties were affected, 45 with buildings. The surface of premises is variable. Mean values are: 500 m² total area, 200 m² constructed, some 50 trees plus bushes and green. Prunus laurocerasus or Thuja sp. are usually planted at the limits. Preliminary treatments had been tested in 1999 (one of the premises) and 2000 (four premises). As results were satisfactory, an informative meeting was officially prepared and a complete agreement was reached for treatment in 2001. The following year, some proprietors declined. Treatments (see details below) involved actions aimed at:

• i) killing ant food sources. Efitax® (alfa-cypermethrin 4%) and Confidor® (imidacloprid 20%) were used to kill aphids by fogging tree canopies. 

• ii) limiting access of ants to their food sources.  Fendona® (alfa-cypermethrin 6%) was applied to tree trunks.

• iii) impeding access to the interior of houses. Baythion® (Foxim 50%) was used for a perimeter treatment in which insecticide was injected around the house, injections being spaced some 30 cm. 

• iv) killing ants already present in houses, by baiting with Blattanex® (Foxim 0.08%). 

Products used in treatments. Values for quantities and time are means.

Ant trails on tree trunks (A) and perimeter points with ants per house (B) in 3 treated zones (T1, T2, T3; n=30 trees per zone; 17-20 points per house) before any treatment (2001) and after treatments of 2002 and 2003.
Ant trails on tree trunks before the treatment (P) and after 1, 3, 7, 15 and 31 days. C1, C2: cotrols; T1, T2 and T3: treated areas.