Abstract
Date palm is a very important fruit crop growing in the world's warm climate. Several pests attack date fruit in the field and in storage. The almond moth, Cadra cautella, is a primary key pest which damages date fruits. Present research shows ultraviolet irradiation effect on mortality and reproduction of C. cautella female larval and female pupal stages in the laboratory.
Female larva aged 18 days and female pupae aged 1–2 days, were directly exposed to ultra violet (UV) type B in a chamber for 0, 2, 4, 6, and 12 h. Mortality of treated larvae and pupae was calculated and compared with the 0 h treatment (control). To quantify vitellogenin gene expression through real time polymerase chain reaction (RT-qPCR), larvae and pupae samples were collected from each treatment after each exposure interval and preserved at −80 °C.
Cadra cautella larvae and pupae, were vulnerable to the UV and the mortality was observed for all exposure intervals showing the highest mortality rate of 90 % larval mortality at 12 exposure interval. Whereas, in case of pupal mortality, 72.26 % mortality was observed after 12 h of exposure intervals. The UV-treated female pupae that survived the pupal developmental stage and emerged as adult moths were not healthy and were mostly deformed, preventing them from emerging from the puparium. Furthermore, when treated female moths emerged, they were unable to copulate with normal male moths, resulting in fewer unfertile eggs. In addition, the lethal effects of UV on vitellogenin gene expression in treated larvae and pupae were confirmed using real-time PCR, the results confirmed that UV had a harmful effect on vitellogenin gene expression.
The current study results are highly encouraging and may be useful in suppressing C. cautella populations in storages and managing this renowned pest of stored date fruits and other agricultural commodities on an industrial/commercial scale.