SPATIAL DISTRIBUTION ANALYSIS OF LEAFMINER (Lyriomyzae trifolii Burgess) EN ONION GROWING AREAS OF NUEVA ECIJA USING GEOGRAPHIC INFORMATION SYSTEM (GIS)

摘要

Analyzing the spatial distribution of a particular pest using various parameters can give an overall view and easy understanding of the condition and continuity of its life cycle. Leafminers (Lyriomyza sp.) are important agricultural pests producing larval mines in leaves affecting many high value crops. In Nueva Ecija, leaffniner is one of the destructive onion pests, however most local farmers ignore its infestation because of the presence of other insect pest called armyworm, well in fact it can also cause a lot of damage to onion like army worm do. Since most of the attention is focused in armyworm, leafrniner infestation and extent of damage to onion areas were often overlooked or neglected by the authorities and local farmers. Geographic Information System offers an advanced technique in creating informative maps which can give further visualization on the present condition of any pest outbreak. To further understand the spatial distribution of leafrniner in the onion fields of Nueva Ecija, GIS was utilized of which Getis-Ord Statistics or Hot Spot Analysis were used to map the distribution of leafrniner using the data gathered from field assessment during onion season. Buffer analysis were also used to determine the spatial relationship between alternate hosts and onion, while, regression analysis was used for temperature-leafminer relationship The hot spot areas of leafrniner during the month of January are the same areas where infested alternate hosts were also located. On the month of March when temperature is higher, an outbreak of leafrniner occurred in almost all of the onion areas in Nueva Ecija most especially in onion areas of San Jose City and Rizal. Thus, the results shows that there is a strong possibilities of recurrence of the leafrniner infestation in areas with elevated temperature and the presence of alternate hosts which coincides during bulb formation stage. The study was able to determine the spatial relationship and distribution pattern of leafrniner with the infested onion areas, as well as the influence of temperature on leafrniner outbreak.