Studies of occurrence of pod borer Heliothis viriplaca in relation to the phenology of chickpea in rain-fed chickpea fields in Kermanshah region of Iran

Abstract

In order to determine the seasonal occurrence of Heliothis viriplaca as well as the best timing of sprays in relation to the phenology of chickpea, light-traps and monitoring methods were applied. All experiments were conducted in two research stations (Mahidasht and Sararood) in 2003 and 2004. The results of adult moths caught by light-traps showed that this pest has only one generation per year and the maximum adult population density appears in the field from end May until early June. The results show that the population density of H. viriplaca was 95% while population density of Helicoverpa armigera and Helicoverpa peltigera were 2 and 3%, respectively. A comparison of the flight peak, the peak of pod borer oviposition, peak of activity of larvae populations and the phenology of plant showed that a period of 13 to 15 days after the flight peak of H. viriplaca was most appropriate for chemical control. This time period coincided with 50% of plant flowering. The field experiments showed that fully grown larvae of H. viriplaca were parasitized by the Habrobracon hebetor, but in this time, most of the larvae had bored the pod of chickpea so this parasitic wasp is likely not to be an adequate agent for pest control.

Key words: Pod borer, Heliothis viriplaca, phenology, light trap.