Ommatissus lybicus Infestation in Relation to Spatial Characteristics of Date Palm Plantations in Oman

Abstract

The agricultural ecosystem and its interaction with the outside environment plays a major role in the population of herbivores. The infestation of the Dubas bug, Ommatissus lybicus, has shown a spatial and temporal variation among different date palm plantations in Oman. This study focused on the relationship of infestation with date palm cultivation environments. The infestation and some selected environmental factors were evaluated in 20 locations for four consecutive infestation seasons over two years. Ordinary least squares (OLS) regression was used to identify the significant factors and the global relationship. Geographically weighted regression (GWR) was used to determine the spatial relationship. The results showed that GWR had better prediction than OLS. The model explained 61% of the infestation variation in the studied locations. The most significant coefficient was the tree planting pattern, the trees planted in uneven rows and columns (irregular pattern) had a positive effect; the infestation increased as the irregularity increased due to an increase in tree density. This reduced the interaction of harsh outside weather with the date palm plantation microclimate. The proportion of side growing area had a negative effect on insect population; as the percentage of side growing area increased as the infestation decreased, assuming the side growing crops hosted natural enemies. The study concluded that the variation of spatial and temporal infestation was primarily due to the variation of the cultural practices and spatial environment of the date palm plantations.

Impact of Initial Population Density of the Dubas Bug, Ommatissus lybicus (Hemiptera: Tropiduchidae), on Oviposition Behaviour, Chlorophyll, Biomass and Nutritional Response of Date Palm (Phoenix dactylifera)

“…Ommatissus lybicus ingests large amounts of sugar-rich palm sap to obtain amino acids required for growth and reproduction, and excretes the surplus sugars [ 22 ]. The substantial secretion of honeydew results in the growth of the black sooty mould, Meliola camellia [ 19 , 23 , 24 , 25 , 26 , 27 ], on fronds, contributing to the accumulation of dust on palm fronds and the intercropped plantation below [ 2 ]. Honeydew is a water-soluble complex comprising of carbohydrates (mainly sucrose, glucose, fructose, and others), amides, amino acids, alcohol, salts, and auxins [ 28 , 29 , 30 , 31 ].…”