Effect of ultra violet irradiation on biological parameters of Plodia interpunctella (Hübner) (Lep., Pyralidae)

The Indian meal moth, Plodia interpunctella (Hübner) is a polyphagous and cosmopolitan species. This species has been distributed in Iran and all over the World. In this research, the effect of UV-irradiation on the biology and life table parameters of P.interpunctella was investigated. Three age groups of eggs (1, 2 and 3-day-old) were exposed to UV-irradiation (254nm wavelength) for 0.5, 1, 1.5, 2, 4, 8, 16, 24, 32, 40 minutes at temperature 25±5ºC and a photoperiod of 10:14 (L:D), without humidity control. The results indicated that all exposure periods of UV-irradiation reduced hatching eggs. An increase in time of exposure to irradiation caused a gradual decrease in percentage of hatching in all age groups of eggs. However, for each exposure duration, the hatching rate was decreased as the age of irradiated eggs increased from 1 to 3 days. Hatching rates decreased from 71.33% at 0.5 min to 0.67% at 8 min exposure time in 1-day-old eggs, from 35% at 0.5 min to 1.67% at 4 min exposure time in 2-day-old eggs and from 31.67% at 0.5 min to 1.67% at 2 min exposure periods in 3-day-old eggs. No hatching eggs occurred at higher exposure times. At three age groups of eggs all exposure periods of UV-radiation increased significantly the incubation period of eggs of males and females in comparison to controls The longest incubation period in males and females was recorded in 3-day-old eggs which treated by 0.5 min exposure time. 7.00±0.00 and 7.67±0.33 days, respectively). There was no significant different between adult longevity of controls and irradiation adult in 1, 2 and 3-day-old eggs. In all age groups of eggs, adult longevity of females was longer than males. The results showed that UVC irradiation has greater effects on the eggs of P.interpunctella than other developmental stages.