ABSTRACT
The present study is initiated to determine the toxic and delayed effects of four botanical oils on the greasy cutworm A. ipsilon, aiming to attain an alternative environmentally safe and effective phytochemicals against the insect-pest. Four botanical oils (camphor, red basil, menthol and rose oil) were added at rates of 0.5 and 1.0% (v/w). The tested oils were added alone, and/or admixed at proportional rate of 1:1 in the prepared baits against the exposed 4th instar till the 6th instar larvae of the insect. The study was run under the laboratory higrothermic conditions of 25±2°C and 65±5% R.H. The results showed that the tested baits of camphor, red basil and menthol oils at concentration rates of 0.5 and 1.0% (v/w) adversely affected the inspected parameters of fitness components of the treated individuals of parent (p) generation. They gave more or less fewer numbers of weak unviable adult-moths, which were either sterile or they laid few numbers of infertile eggs and died before the induction of (F1) progeny. That failure could be elucidated by the rapid occurrence of drastic effects on the biological performance of both the influenced sexes of adult-moths along the period of parent's development. Finally it ended by the inhibited induction of (F1) progeny. A delayed effect of the prepared baits of rose oil at 0.5 and 1.0% (v/w), was assessed on the following raised F1, F2, F3 and F4 generations after parent's treatment. The delayed effect was detected as less efficient latent effect on each of these consequently raised generations; characterized by the gradual decrease of the number of alive immatures and adult-moths. The effect was recorded as gradual increase of dead and malformed individuals and adult-moths. In addition to the gradual decrease of deposited and/or hatched eggs up to the 4th generation, which ended by the complete failure of the development. That failure could be also attributed to the cumulated effects of the induced recessive lethal genes in both the influenced sexes during the periods of raised F1, F2 and F3 generations. The recessive lethal genes caused drastic unprofitable effects that appeared at the beginning of the 4th generation that failed. Also, the tested baits (0.5 and 1.0%, v/w) of each of admixed camphor, red basil and menthol oil with rose oil (1:1), greatly affected the developmental parameters of the treated insects. The highest efficient toxicity and an adverse biological performance of the admixed camphor and/or red basil oils with rose oil at 0.5 and 1.0 (v/w), and menthol/rose oil at 0.5% (v/w) on the treated parent generation were detected. The previous treatment gave unviable sterile adults, which died before the induction of (F1) progeny. That recorded failure of (F1) proves the fastest toxic efficiency and a drastic biological performance which were entirely unable to induce (F1) progeny. The tested bait of mixed menthol/rose oils (1.0%, v/w), showed significant reduction in all studied parameters of F1 and F2 fitness components. The tested bait raised sterile unviable adult-moths of (F2) generation which furtherly ended by the distinct failure of (F2) development. This effect may be caused by the cumulative effects of the induced recessive lethal genes in both of the affected sexes through the developmental period of (F1) generation after (P) one treatment, inducing apparent drastic effects, which were revealed at the beginning of (F2) generation. Remarkably, the inspected faster or slower occurred toxicity and drastic biological performance of these admixed botanical oils, may be referred to the synergistic action for most of the evaluated mixtures or/and the additive one for menthol/rose oil (1.0%), which needs further investigation.
