Impact of numerous larval diets on the biology of pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) under laboratory conditions

Abstract

BackgroundPink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) has become a potential pest of cotton by causing substantial yield losses around the world including Pakistan. Keeping in view the facts like limited research investigations, unavailability, and high cost of artificial diet’s constituents and their premixes, the present research investigations on the dietary aspect of P. gossypiella were conducted. The larvae of P. gossypiella were reared on different diets that were prepared using indigenous elements. The standard/laboratory diet comprised of wheat germ meal 34.5 g, casein 30.0 g, agar–agar 20.0 g, sucrose 10.0 g, brewer’s yeast 5.0 g, α-cellulose 1.0 g, potassium-sorbate1.5 g, niplagin 0.5 g, decavitamin 0.01 g, choline-chloride 0.06 g, maize-oil 3.30 g, honey 2.0 g, and water 730.0 mL. Alternatives to cotton bolls and wheat germ meal were okra seed sprouts, okra fruit, cottonseed meal, and okra seed meals, which were included in the study to introduce an efficient and economic mass-rearing system.ResultsThe larval development completed in 19.68 d ± 0.05 d with a weight of 20.18 mg ± 0.20 mg at the fourth instar fed on the cottonseed meal-based diet instead of wheat germ meal based diet. On the same diet, 84.00% ± 4.00%, 17.24 mg ± 0.03 mg, and 7.76 d ± 0.06 d were recorded as pupae formation, pupal weight, and pupal duration, respectively. Adult emergence, 76.00% ± 1.00% was recorded from pupae collected from larvae raised on cottonseed meal-based diet. These male and female moths lived for 40.25 d ± 0.10 d, and 44.34 d ± 0.11 d, respectively. Females deposited 21.28 ± 0.04 eggs per day with the viability of 65.78% ± 0.14%. The larval mortality at the fourth instar was 37.20% ± 1.36% and malformed pupation of 12.00% ± 1.41% was recorded. Replacement of wheat germ meal with that of local meals (cottonseed and okra seed) in the standard laboratory diet has saved 463.80 to 467.10 PKR with 1.62 to 1.63 cost economic returns, respectively.ConclusionThis research is of novel nature as it provides a concise and workable system for the economic and successful rearing of P. gossypiella under laboratory conditions.