Chemical Composition of Essential Oils Derived from Eucalyptus and Lemongrass and Their Antitermitic Activities Angainst Microtermes mycophagus (Desneux).

Abstract

The essential oils of eucalyptus (Eucalyptus citriodora) and lemon grass (Cymbopogon citratus) were analyzed by GC-MS and tested against economically important termite species of Pakistan i.e., Microtermes mycophagus (Desneux). Their physical parameters were also scanned. The major constituents identified in eucalyptus oil are: eucalyptus, limonene, terpinen-4-ol, gravenone, n-tetradecane, 2,2¢6,6¢-tetramethyl piperidin-4-ol, piperitone and the chemical components of lemon grass oil are: myrcene, citronellol, citral, nerol and neric acid. The repellency, toxicity, fumigation activities of test oils and tunneling behaviours of M. mycophagus were evaluated. At 25 μg/10μL oil concentration, lemon grass showed 63.33 % and eucalyptus oil showed 62.22 % mortality and at the same concentration, the repellency test revealed that both eucalyptus and lemon grass oils showed efficient repellency i.e., 42.6 and 36.33 % respectively. Fumigation results revealed that lemon grass caused 100 % mortality at 5 ppm concentration on 9^th day of treatment whereas eucalyptus gave same result in the end of test period (day 12). When tunneling behaviour was observed for M. mycophagus, the average time to cross the tube at 50 μg was 28 and 50 h in eucalyptus and lemon grass oil one-to-one.