A comparison between two population census methods, pitfall trapping and visual searching, for Pardosa astrigera (Araneae: Lycosidae) in cabbage fields

Abstract

The trends of population census data of the wolf spider, Pardosa astrigera L. Koch, in cabbage fields were compared between two methods of the census: pitfall trapping and visual searching. Although there were usually no significant correlations between the data obtained either method, the number of spiders captured by pitfall trapping per trap each week and the number of spiders observed by visually searching per five meters of two cabbage rows had roughly equivalent average values through out the census period. Therefore, when estimating whether the population of spiders in cabbage fields is above a certain level, the average values of each population census method throughout the census period were comparable to each other to a certain degree.