Studies on the distribution of Pachycondyla sennaarensis (Hymenoptera: Formicidae: Ponerinae) in Saudi Arabia. 1. Ar-Riyadh region.

In Ar-Riyadh Region in the Kingdom of Saudi Arabia (KSA), the Governorates of Al-Zulfi, Al-Ghat and Al-Majmah (north zone), of Al-Hariq, Al-Aflaj and Hawtat Bani Tamim (south zone), of Hijrat Sa`ad (east zone), of Shaqra, Durma, Al-Qasab, Huraimela`a (west zone) and Riyadh City (central zone) were surveyed for the presence of Pachycondyla sennaarensis monthly during the period from December 2007 to December 2009. The ant was not detected in Al-Majmah or Al-Zulfi. It was detected in Al-Ghat and Hijrat Sa'ad only in 2009, while it was found in small numbers in 2008 and in large numbers in 2009 in all west zone Governorates; which suggest that the ant was actively spreading in these localities. Large numbers of the ant were detected in the south and central zones' Governorates during both years. The positive localities were infested more heavily during spring and summer. The ants seemed to have adapted to the hot and dry weather of Riyadh Region especially in spring and summer by establishing the nests in moist sand in irrigated gardens, parks, housing areas and roadside plantations. This ant is a condemned health hazard and more field studies and quarantine measures are essential for its control.