Survival of Steinernema masoodi and S. carpocapsae (Rhabditida: Steinernematidae) on pigeonpea and chickpea after foliar application

Abstract

The survival of Steinernema masoodi and S. carpocapsae (Rhabditida: Steinernematidae) was investigated after foliar application on pigeonpea and chickpea twigs, respectively, at flowering and fruiting stage. The concentration used was 2500 infective juveniles (IJs)/ml water for both the species. On pigeonpea, the mean number of IJs of S. masoodi found alive were 303.4, 158.4 and 51.6 after 0, 30 and 60 minutes of spray in evening hours whereas 236.1, 44.4 and 6.8 IJs were found alive when sprayed in morning hours, respectively. S. masoodi survival at 30 minutes post-spray in the morning was on par with 60 minutes post-spray in the evening hours. On chickpea, the mean numbers of IJs of S. carpocapsae were 165.4, 65.8, 4 and 0 at 0, 1, 2 and 3 h post-spray in the morning hours whereas in the evening spray, 159.4, 111.8, 83.8 and 11.4 IJs found alive at 0, 1, 2 and 3 h post-spray, respectively. Overall, nematode survival in the evening hours was higher compared to morning spray at a given time. Addition of glycerine and UV retardant improved the survival of nematode. Results indicated that survival rate of IJs decreased fast and viability remained up to 3 h and in evening hours very few nematodes remained alive. Serious attempts are needed to improve the survival of nematodes after foliar spray by adding efficient adjuvant, humectant, antidesiccant and/or UV retardant for the management of aerial insect pests.