Effect of Soil Moisture and Soil Texture on Oviposition by Japanese Beetle and Rose Chafer (Coleoptera: Scarabaeidae)

Abstract

In choice tests, Japanese beetles, Popillia japonica Newman, laid more eggs the wetter the soil, up to about field capacity. No eggs were laid in soils with less than or equal to 55% moisture content. Even in nonchoice tests, Japanese beetles laid few eggs in dry soils. In choice tests, Japanese beetles laid more eggs in soils with medium clay contents than other soil textures. In nonchoice tests, Japanese beetles laid similar numbers of eggs into a wide range of soil textures, except fewer eggs were laid into pure sand. In choice tests, rose chafer, Macrodactylus subspinosus (F.), also laid many more eggs in wetter soil than in drier soil. In choice tests, rose chafers showed no preference for oviposition in any of the soil textures tested. These data help explain the patchy distribution of Japanese beetle larvae and of rose chafer adults after dry summers, but do not explain reported occurrences of rose chafer larvae only in sandy soil.