Fumigant toxicities of essential oils and two monoterpenes against potato tuber moth (Phthorimaea operculellaZeller)

Abstract

SummaryIntroduction:The potato tuber moth (PTM) is the major economic pest of potato. Different approaches were tried to prevent and control this pest including natural pesticides and synthetic fumigants.Objectives: This study was conducted to evaluate the insecticidal activity of the essential oils of thyme and myrtle. In addition to evaluating the insecticidal activity of carvacrol and eucalyptol against the different life stages of potato tuber moth using a fumigation bioassays.Methods:Thyme and myrtle oils were extracted from wildThymus syriacusBoiss. and wildMyrtus communisL. by hydrodistillation. Fumigation experiments were conducted on potato tuber moth of different stages of development (eggs, larvae, pupae, and adults), using standard methods. The potato tuber moth was treated for different periods using different concentrations of the essential oils. One-way analysis of variance (ANOVA) was applied on the mortality percentages data to estimate the significance of differences between treatments atp<0.05. Probit analysis was used to estimate the LC50, LC90and LT50.Results:Adult stage was the most sensitive to essential oils vapours with LC50value of 0.5μl/l air. Whereas, pupal stages were the most tolerant. The essential oil of thyme possessed the strongest fumigant toxicity against eggs with a LC50value of 6.1μl/l air. The two monoterpens showed varied fumigant toxicity against adult stage. Carvacrol achieved 100% mortality at 0.125μl/l air after 6 h, and 0.025μl/l air after 48h exposure with LT50period of 0.5 h.Conclusion:The present work demonstrated thatT. syriacusessential oil is a promising natural fumigant against the different developmental stages of PTM.

The Potential Distribution of the Potato Tuber Moth (Phthorimaea Operculella) Based on Climate and Host Availability of Potato

“…When germinating, the crop should be thoroughly earthed up for 30-40 days after planting [59]. To prevent further dispersion, it is necessary to focus on the management of the potato tuber moth, using, for instance, microbial control or fumigation [60][61][62][63]. In addition, Chandel and Chandla [8] reported that Bacillus thuringiensis and granulosis virus can reduce the infection rate of the potato tuber moth from 4.17%-8.59% to 0.32%-0.87%.…”

Fumigate efficacy of Juniperus foetidissima essential oil and two terpenes against Phthorimaea operculella

“…The applied oil concentrations were chosen to identify the one that achieve a 100% mortality. Fumigation experiments were designed as reported in a previous study [10]. Adults and larvae were fumigated in jars, (1 liter air volume), while eggs and pupae, (3-5 days old), were fumigated in Petri dishes,(160 cm 3 air volume).…”

“…The toxic effects of citronellol and nerol against adult insects (one day old) were investigated as reported in a previous study [10]. Adults were considered dead when no leg or antennal movements were observed.…”

“…Numbers of pupae and adults resulting from the first generation were recorded in kind and account for three independent experiments, in addition to the non-treated control. Statistical analysis and calculation of LC 50 and LC 90 were made according to our previous study [10].…”

“…Monoterpenoids extracted from essential oils have a role in defending plants. Some monoterpenoids are very toxic to insects, while others are repellent or have inhibitory effects [8][9][10]. Most of botanical insecticides have minor toxicity to non-target organisms, and rapidly biodegrade [6,11].…”