Mohammad El-Sayed Mohammad Hegab^*(1)

(1). Plant Protection Research Institute, ARC, Dokki, Giza, Egypt.

(*Corresponding author: E-Mail: drmhegab@yahoo.com).

Received: 02/05/2018                                Accepted: 01/10/2018

Abstract

The effectiveness of boric acid on pink bollworm, Pectinophora gossypiella (Saunders) and spiny bollworm, Earias insulana (Boisd.) was evaluated at the Plant Protection Research Institute, Sharkia Branch, in Egypt. The results indicated that all studied concentrations of boric acid have a toxic effect on the larvae of pink and spiny bollworms. On the other hand, the delayed effects of boric acid on the two insects showed an increase in the percentage of larval and pupal mortality. The highest mortality rate was for larvae and pupae at 6.00% concentration (52.00 and 88.73%) and (56.00, 66.72%) for pink and spiny bollworms compared with 0.00 and 8.00 and 0.00 and 6.67% respectively. There was also a significant reduction in the duration of the larvae stage, the rate of pupation and the pupal period of pink and spiny bollworms. There were no significant differences between the concentrations of boric acid and the control in the case of weight of pupae and larvae between concentrations measured for boric acid and control. There is a high reduction in the rate of adult emergence percentage compared to control. There were also non-significant and significant effects on egg laying periods, male and female longevity and sex ratio. The concentrations of boric acid showed a significant decrease in the amount of eggs (8.67 and 19.33 eggs/female) at 6.00% concentration of pink and spiny bollworms compared to 226.33 and 184.67 eggs/female in the control. The highest reduction in the number of laid eggs to pink and spiny bollworms at a concentration of 6.00% was (0.00 and 52.35 eggs/female) compared to 95.61 and 94.92 eggs/female, respectively in the control. When the eggs of the pink and spiny bollworms were dipped in each of the four concentrations tested for boric acid for a period of 50 seconds, the highest concentration (6.00%) showed an increase in the non-hatching rate of pink and spiny bollworms (62.33 and 51.33%) compared to 7.00 and 10.33%, respectively in the control. When feeding pink and spiny bollworms moths on four concentrations of boric acid, the results showed a significant reduction in egg laying periods, male and female moths and a high reduction in the number of eggs (0.00 and 4.33 eggs/female), respectively treated with 6.00% concentration compared to (200.00 and 127.00 eggs/female) in the control. The results showed that the second, third and fourth concentrations of the boric acid had a significant effect on pink bollworm, which prevented egg hatching. In the case of the spiny bollworm, it was found that the eggs treated with concentration of 6.00% did not hatch compared to 90.83 and 88.94% in the control.

Key words: Pink bollworm, Pectinophora gossypiella; Spiny bollworm, Earias insulana, Boric acid.

Full paper in English: PDF