Sci.Int.(Lahore),29(4),833-836, 2017 ISSN 1013-5316;CODEN: SINTE 8 833 July-August FIELD ASSESSMENT OF ABUNDANCE, HOST PLANT UTILIZATION AND BEHAVIOR OF THE INVASIVE PHYTOPOLYPHAGOUS GIANT AFRICAN SNAIL, ACHATINA FROM SELECTED SITES IN MINDANAO, PHILIPPINES Genelyn G. Madjos 1, 2 , Cesar G. Demayo 1 1 Department of Biological Sciences, MSU-Iligan Institute of Technology, Tibanga, Iligan City 2 Department of Biology and Natural Sciences, Western Mindanao State University, Baliwasan, Zamboanga City Correspondent Email: genelyn_madjos@yahoo.com ABSTRACT: We conducted an assessment of abundance, host plant utilization and behavior of the invasive Phytopolyphagous giant African snail, Achatina from selected sites in Mindanao, Philippines in situ. The study was carried out in protected montane areas (Pasonanca Natural Park, Zamboanga City and Initao-Libertad Protected Landscape and Seascape, Misamis Oriental) and suburban ecosystems (Pagadian City and Cagayan de Oro City) in Mindanao, Philippines. Results of the assessment show that out of the twenty-five (25) identified plants, they preferred succulent food plants such as Carica papaya, Colocasia esculenta and Operculina turphetum. They were also found aggregating in plant litters which maybe a source of providing moisture to the organism. Results show that the feeding of A. fulica is dependent on plant community composition and varies according to quality and quantity. Absence of native gastropod fauna could be related to its difficulty to compete with A. fulica. Results reveal that the phytopolyphagous nature of A. fulica facilitates the establishment of their population. KEYWORDS: Phytopolyphagous, abundance, invasiveness, biodiversity 1.0 INTRODUCTION An invasive species such as Achatina fulica (Fig. 1) is considered as one of the greatest threat to native biodiversity next to habitat destruction. This snail known as the giant African snail is a fast-growing invasive phytopolyphagous pest considered as the most ecologically damaging land snail and ranks second among the “100 Worst Alien Invasive Species” [1]. This pest caused crop yield losses by herbivory, transmits plant pathogens and higher costs of pest control including adverse effects on indigenous gastropods that may arise through competition [1, 2, 3]. It also has invaded many suburban habitats including protected areas [4]. Considering that the data on the impact of this invasive species on native biota in the Philippines are scarce [4,5,6,7], information about A. fulica’s feeding preferences and behavior is important to be able to assess the extent of invasiveness of the pest by looking at its distribution and field behavior. Thus this field observation study was conducted. Figure 1. Adult A. fulica (a) and the eggs (b) 2.0 METHODOLOGY Opportunistic sampling of Achatina fulica was done from August to November 2015 during different periods, including rainy days, in four areas of Mindanao, Philippines: Pasonanca Natural Park in Zamboanga City, suburban areas in Pagadian City, Initao-Libertad Protected Landscape and Seascape area and the urban area of Cagayan de Oro City. A corresponding gratuitous permit was obtained from the Department of Environment and Natural Resources (DENR) for the protected areas. Purposive sampling of A. fulica was employed to maximize its occurrence in the area. Reconnaissance and prior interview were also conducted in communities to determine if there were occurrences of the snail in the area. Food preferences of the snail were done by actual observation of the behavior of the snail in the field. Vegetation were assessed for each of the sampling sites using the random meander method [8] rather than quadrats, to maximize the opportunity of detecting significant or sparsely distributed flora species utilized by A. fulica. Observation was also done on the presence of native snail fauna in the area. Abundance was determined for each of the selected sampling areas. 3.0 RESULTS AND DISCUSSION Field counts of A. fulica in selected sampling sites of the four areas in Mindanao, Philippines are shown in Table 1. Table 1. Species abundance of A. fulica in four sampling sites in Mindanao, Philippines. Sampling Sites Abundance Pasonanca Natural Park, Zamboanga City (protected area) 201 Pagadian City 137 Initao-Libertad Protected Landscape 350 Cagayan de Oro City 90 A. fulica was more abundantly found in protected areas where entrance of people is limited than suburban ecosystems. This is contrary to the works of Albuquerque et al. [9] where the snail was most abundant in sites with high human density which was argued to be responsible for its establishment and dispersion. USDA [2] reported that A. Fulica is currently confined to mostly residential settings where plant loss would be confined to landscaping and garden plants. Our results were in contrast to these studies since the Initao-Libertad Protected Landscape has the highest number of individuals seen (N=350). This could be due to the growth of young seedlings, more decaying plant litter and