title: Seasonal abundance of two armyworm species, Spodoptera exitgua (Hübner) and Spodoptera litura (F.) in the Philippines.
abstract: The two armyworm species Spodoptera exigua (Hübner) and S. litura (F.) are Important pests on several agricultural crops in the tropics. Knowledge about species abundance is important for the development of integrated pest management strategies. During 1998 and 1999 population densities were recorded weekly using pheromone traps at San Leonardo and Munoz (Province Nueva Ecija, 150 km north of Metro Manila) on the Philippine island Luzon. Furthermore, meteorological conditions and natural enemies were observed. Both armyworm species were present year-round at both observation sites. No differences in numbers of male insects trapped in pheromone traps between seasons were found for S. litura. Contrary, numbers of male S. exigua trapped during rainy season was significant higher than during dry season. Rainfall explained between 30 and 40% of trapped moths and has to be considered when monitoring population density with pheromone traps. Parasitism rates were below 5% in both years and for both species and can not explain the high variation observed in population densities.
authors.affiliation: Humboldt University Berlin, Institute for Horticultural Science, Urban Horticulture Lentzeallee 75, D-14195 Berlin, Germany.
authors.forename: Ch
authors.initials: Ch
authors.lastname: Ulrichs
authors.forename: I
authors.initials: I
authors.lastname: Mewis
mesh_terms: D000818:Animals; D002980:Climate; D018556:Crops, Agricultural / Q000469:parasitology; D005260:Female; D008297:Male; D010675:Pheromones; D010679:Philippines; D011156:Population Density; D012621:Seasons; D012727:Sex Characteristics; D018411:Spodoptera / Q000254:growth & development*
chemical_list: D010675:Pheromones