evaluation of some plant essential oils against the brown-banded cock-roach, supella longipalpa (blattaria: ectobiidae), a mechanical vector of human pathogens

background: essential oils, as secondary plant compounds, present a safer alternative to conventional insecticides in insect control programs. so five essential oils including eucalyptus, mint, yarrow, oregano and rosemary oils were evaluated against the brown-banded cockroach supella longipalpa . methods : evaluation was done against the 3 rd and 4 th instar nymphs using three bioassay methods; continuous con­tact toxicity, fumigant toxicity and repellent activity. the study was done in the laboratory of medical entomology, during april 2012 to september 2013. results: mortality rates by the lowest concentration (2.5%) of rosemary, oregano, yarrow, eucalyptus and mint oils were 100%, 62.2%, 45 %, 36.2% and 5.2% at 24 h after exposure respectively. rosemary oil was determined as the most toxic oil because of 100 % mortality rate at the concentration range of 2.5% to 30%. the lowest fumigation effect using 50 µl /l air was recorded from mint oil with 97.2 % mortality after 24 h, while the other oils caused 100% mortality. the most repel activity was related to oregano oil which showed 96.5–99.1% repellency at the con­centration range of 2.5–30% with a residual effect lasting at least a week after treatment. conclusion: oregano oil could be used as a potential repellent against s. longipalpa . also, all five essential oils could be used as the safe compounds for surface treating or fumigation in cockroach control programs while rosmary and oregano oils exhibited the most toxicity.