Parasitoid fitness and quality of Corcyra cephalonica (Stainton) eggs after vacuum packaging combined with cold storage

Abstract

Corcyra cephalonica (stainton) eggs are frequently used to produce Trichogramma spp. Storing host eggs by staggering their development to improve continuous host egg production and their viability for rearing can help synchronize their mass production during high seasonal demands. This study aimed to evaluate the effects of vacuum packaging on the fitness of C. cephalonica eggs. The host C. cephalonica eggs were treated in three ways before cold storage at 4 °C: exposing to ultraviolet, vacuum packaging and exposing to ultraviolet and vacuum packaging. At 10, 15, 20, and 25 days post-storage, the host eggs were exposed to Trichogramma. The eggs' relative amounts of parasitism and emergence, parasitoid emergence rate, total protein, and free amino acid content were measured. Vacuum packaging increased the relative amount of parasitism and emergence within 20 days of storage. The average protein content of the host eggs was significantly higher in vacuum-packed and activated host eggs. Storage increased the contents of glutamate, serine, glycine, arginine, threonine, proline, valine, methionine, and leucine, while decreasing the contents of alanine and isoleucine. Vacuum packaging decreased the content of free amino acids, including aspartic acid, glutamic acid, serine, glycine, histidine, arginine, proline, tyrosine, valine, isoleucine, and phenylalanine. It increased the levels of alanine and leucine. Vacuum packaging is beneficial for prolonging the cold storage period of C. cephalonica eggs as a parasitoid host by preventing protein degradation. The best preservation time was 20 days.