Periodic crossbreeding between laboratory and wild populations enhances fitness in Helicoverpa zea (Boddie) infected with Nuclear Polyhedrosis Virus (NPV-Hz)
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Background Helicoverpa zea is a polyphagous pest that causes damage to various crops during both flowering and fruiting stages. Despite being an economically significant pest in our country, studies on its biological and reproductive aspects have been limited. The general objective of this study was to determine the duration of the life cycle of Helicoverpa zea, host of the Nuclear Polyhedrosis Virus (NPV-Hz), across three generations (G1, G2, and G3) under laboratory conditions from March to December 2020. The general objective of this study was to determine the duration of the life cycle of Helicoverpa zea, host of the Nuclear Polyhedrosis Virus (NPV-Hz), across three generations (G1, G2, and G3) under laboratory conditions from March to December 2020. Methodology : The work began with the collection of biological material from corn crops, where third and fourth instar larvae were gathered and subsequently transferred to the quarantine laboratory. They underwent a quarantine process for two consecutive generations. After this, the insect breeding was moved to the rearing laboratory to evaluate the complete life cycle over three generations, ultimately establishing a breeding stock for the production of NPV-Hz. This was conducted in the noctuid insect rearing laboratory. Results The complete life cycle of Helicoverpa zea ranges from 40 to 46 days, with the following average durations: 4 days for the egg stage, 15 days for the larval stage, 11 days for the pupal stage, and 15 days for adults. Average oviposition rates per generation were 2,765 eggs for Generation I, 2,731 eggs for Generation II, and 2,881 eggs for Generation III, with the highest rate observed in Generation III. Average pupal weights increased progressively, with weight percentages of 32%, 33%, and 35% for Generations I, II, and III, respectively, indicating enhanced fitness in later generations due to periodic crossbreeding.
