Life table of Khapra beetle, Trogoderma granarium (Everts) on different rice cultivars and lethal and sub-lethal effects of some plant essential oils on this pest in laboratory condition

Rahimi Ashjerdi, Abbas (2020) Life table of Khapra beetle, Trogoderma granarium (Everts) on different rice cultivars and lethal and sub-lethal effects of some plant essential oils on this pest in laboratory condition. Masters thesis, University of Mohaghegh Ardabili.

Text payan22 3(Autosaved).pdf Download (603kB)

Abstract

Rice, Oryza sativa L. is an annual plant in Gramineae and it is one of the main foods for most people in the world, especially in Asia. The khapra beetle, Trogoderma granarium (Evert) is the most important pest in stored products that has been resistant to conventional respiratory compounds such as methyl bromide, phosphine and some insecticides (malathion and phosphotoxin). Plant essential oils can be suitable substitutes for respiratory compounds in pest control due to their environmental compatibility. In this research, effects of ten rice cultivars including Gilaneh, Gohar, Domsiah, Kadoos, Khazar, Fajr, Shiroodi, Ali Kazemi, Neda and Hashemi on life history parameters of T. granarium were investigated. The insecticidal properties of the essential oils of Mentha pulegium L., Achillea millefolium L., Heracleum persicum L., Cinnamon verum L. and Allium sativum L. were also determined. Research method: Life table study on each rice cultivar was done by preparing a cohort of T. granarium eggs and the parameters were calculated by two-sex life table program. Plant essential oil was obtained by Clevenger apparatus. Bioassay experiments were performed on the egg and fifth instar larval stages of T. granarium. Experiments were carried out in a completely randomized design and under laboratory conditions (33±1 °C, 65±5% of relative humidity, 14 h light and 10 h dark). Five concentrations of each essential oil were used in four replications. Also, the sub-lethal effects of LC30 concentration of essential oils on T. granarium on Gilaneh and Khazar cultivars, as appropriate and inappropriate cultivars, respectively were investigated. Findings: Based on the results, the shortest immature period was on Gilaneh (46.86 days) and the longest on Khazar (55.74 days). Also, the highest fecundity was observed on Gilaneh (59.43 offspring) and the lowest on Khazar (47.28 offspring). The intrinsic rate of population increase (r) was the highest in Gilaneh (0.064 day-1) and the lowest in Khazar (0.049 day-1).LC50 values showed that egg development stage of T. granarium was more sensitive than the fifth instar larvae stage.Respiratory toxicity of essential oils significantly increased with increasing concentration. Also, LC50 results showed that A. sativumhad the highest mortality rate on this pest. The LC50 values for egg and fifth instar larval stages were 6.84 and 10.13 µl on Gilaneh and 4.09 and 8.74 µl on Khazar after 24 h, respectively. A. millefoliumshowed the least toxicity among treatments. The highest fecundity was observed in control and the least in garlic treatment in both Khazar and Gilaneh cultivars. Net reproductive rate (R0) varied from 13.18 offspring in garlic treatment to 28.44 offspring in control on Gilaneh and from 6.28 offspring in garlic treatment to 19.18 offspring in control on Khazar cultivar. Conclusion: According to the results, Khazar cultivar is an inappropriate cultivar for population growth of T. granariumand this finding can be useful in pest management program of this pest in rice storage rooms. Furthermore, essential oil of A. sativum, as a safe compound can be used against T. granarium in combination with other control methods including resistant rice cultivars, especially Khazar.

Actions (login required)

View Item