Aceria guerreronis Keifer, a mite pest of coconut in Dhofar coastal plain in the Sultanate of Oman : the prevalance, distribution, impact and growers' perception

Although there are several species of phytophagous mites living underneath the coconut perianth, feeding on tender tissues of the young coconut fruit and causing similar visual symptoms, the coconut mite, A. guerreronis Keifer, has proven to be one of the most serious mites of coconut crops all over the world. Sustainable management of A. guerreronis still faces various challenges, since being described as a destructive pest of coconut in 1965 in Mexico. These challenges have been related to several biotic and abiotic characteristics of the mite and the coconut host. These characteristics were assumed to be solely, or in combination, responsible for the yield reductions. The ideal achievements of practical sustainable control measures, applied to contain the pest, were not satisfactory. The current study was conducted in Dhofar coastal plain of the Sultanate of Oman during the period 2008 - 2010. The study was designed based with four principal themes, as main objectives, which have been investigated in order to better understand some of most important aspects of A. guerreronis behaviour and its impact in Dhofar coconut plantation system, in line with the knowledge and perception of coconut growers and their importance for the successful management of A. guerreronis in Dhofar coastal plain. The study methodology used carefully designed field surveys and questionnaires, fruit sampling and identification techniques applied to acarology and socioeconomic analysis for coconut growers. The findings of this study presented several outcomes. The population dynamics of A. guerreronis and associated arthropods have been assessed in relation to the spatiotemporal conditions in the study area. Biotic dispersal pathways have been evaluated, especially on coconut fruit ages on the tree as well as on fallen fruits and seedlings. An original dispersal pathway has been assessed on date palm seedlings; it was observed that A. guerreronis could develop on this host. A novel approach has been carried out to assess yield losses, especially concerning fruit characteristics at the different consumption types. It was also observed that all the surveyed coconut holdings were infested by A. guerreronis; 40% of Omani growers assumed that the main problem of coconut production was A. guerreronis and only 32% declared that measures to control this pest were required. Large number of respondents revealed that they could identify the infestation of pests and diseases on the coconut crop. However, due to lack of knowledge and proper guidelines, non-availability of chemicals and high cost of plant protection chemicals, growers could not adopt the control measures in time to protect coconut crop. Adoption of the best plant protection measures needs complicated decision making as it involves skills and presents many risks; since most growers are small landholders and have very low income they are not prepared to take any risk for further inputs. In addition to the non-availability of plant protection inputs, lack of technical knowledge regarding plant protection measures results in poor adoption of plant protection measuresEThOS - Electronic Theses Online ServiceGBUnited Kingdo