Prediction of survival ratios of Cadra cautella (Lepidoptera: Pyralidae) different life stages after treated with ultraviolet radiation in dates.

ABSTRACT

Date palm, is a tree of economic importance which is grown around the world, including Saudi Arabia. Its fruit is nutritious and possesses medicinal benefits. Almond moth, is a serious date fruits pest in the field as well as in the storage and causes severe economic losses. In the given research, ultraviolet radiation type B (UV-B, 315 nm) harmful effects were evaluated against all developmental stages of C. cautella. One and 3-d-old eggs, 12 and 18-d-old larvae, 1-d and 6-d-old pupae, and 1-d-old adults, were exposed to UV-B for different intervals. Eggs were exposed for 0-30 min and 0% hatchability was achieved both for 1-d and 3-d-old eggs after 30 min. The larvae were exposed for 6-24 h, and after 24 h, mortality was 100 and 97% for 12 and 18-d-old larvae, respectively. Similarly, the pupae were exposed for 0-30 h, and 100% mortality was achieved after 30 h for 1-d-old pupae. Furthermore, none of the 6-d-old pupae emerged as an adult after 12 h of exposure. When adults were exposed for 1-4 d, no mortality was observed; however, UV-B reduced fecundity and hatchability in the treated adults. The susceptibility order was as follows eggs > larvae > pupae > adults. Several uncharacteristic behaviors of C. cautella were noted, such as females depositing eggs openly on food items and containers, mature larvae exiting from food, larvae starting to wander for pupation, and pupation occurring typically outside the food. The application of UV-B could be an effective management strategy because all developmental stages of C. cautella were susceptible to UV-B that might be helpful to protect the dates from C. cautella infestation.