Effect of Irrigation on Within-Grove Distribution of Red Palm Weevil Rhynchophorous ferrugineus

The red palm weevil (RPW) Rhynchophorous ferrugineus (Oliv.) is the most important pest attacking date palm trees. The objective of this study was to determine the effect of drip and flood irrigation on the within-grove distribution of RPW. The current study was started with the first appearance of the infestation to almost disappearance of the infestation. Results showed that more infested trees were detected in plots with flood irrigation. The number of infested trees in these plots represented 89% of the total infested trees. This study suggested that irrigation management and soil moisture are key factors in the dispersion of the RPW infestation and could be used as one of the integrated pest management tools.

Efficacy of Gamma Irradiation Against Sitophilus granarius L. ( Coleoptera : Curculionidae )

The lethal and sterilizing responses to gamma irradiation of eggs, larvae, pupa, and three-day and four-week old adults of Sitophilus granarius were investigated. Doses were 0, 10, 30, 50, 70, 100, 300 and 500 Gy. Eggs and larvae were unable to develop to adults following doses of 30-500 Gy. Emergence of adults from irradiated eggs and larvae occurred at a dose of 10 Gy. Pupae developed to the adult stage following doses of 10-70 Gy. A dose of 70 Gy at the pupal and four-week old adult stages caused sterility. Three-day old adults were most tolerant of irradiation and required 100 Gy for sterility. The percentage of damage to wheat grains caused by preadult stages following various irradiation doses was determined

Use of Radiation Disinfestation in the Control of Oryzaephilus surinamenesis L. : a Pest of Stored Dry Dates

A preliminary biological study of Oryzaephilus surinamenesis was conducted to determine the duration of preadult stages. The lethal and sterilizing effects of gamma radiation on eggs, larvae, pupae, three-day and four-week old adults of O. surinamenesis were investigated. Doses were 0.0, 0.1, 0.3, 0.5, 0.7, and 1.0 kGY. Eggs and larvae were unable to develop to adults at any dose. Pupae were able to reach adult stage at doses of 0.1 – 1.0 kGy but adults emerged from irradiated pupae failed to produce progeny. Three-day old adults were most tolerant of irradiation but a complete sterility occurred at doses of 0.3 kGy and above. These results indicate that a commercial irradiation treatment at a dose of 0.3 kGy should effectively disinfest stored dates against this pest

Predicting the potential geographical distribution of parasitic natural enemies of the Dubas bug ( Ommatissus lybicus

The Dubas bug (Ommatissus lybicus de Bergevin) is a pest species whose entire life cycle occurs on date palms, Phoenix dactylifera L, causing serious damage and reducing date palm growth and yield. Pseudoligosita babylonica Viggiani, Aprostocetus nr. Beatus, and Bocchus hyalinus Olmi are very important parasitic natural enemies of Ommatissus lybicus in northern Oman. In this study, random farms were selected to (a) model the link between occurrences of the Pseudoligosita babylonica, Aprostocetus nr beatus, and Bocchus hyalinus (dependent variables) with environmental, climatological, and Dubas bug infestation levels (the independent variables), and (b) produce distribution and predictive maps of these natural enemies in northern Oman. The multiple R2 values showed the model explained 63%, 89%, and 94% of the presence of P. babylonica, A. nr beatus, and Bocchus hyalinus, respectively. However, the distribution of each species appears to be influenced by distinct and geographically associated climatological and environmental factors, as well as habitat characteristics. This study reveals that spatial analysis and modeling can be highly useful for studying the distribution, the presence or absence of Dubas bugs, and their natural enemies. It is anticipated to help contribute to the reduction in the extent and costs of aerial and ground insecticidal spraying needed in date palm plantations