Is Heliothis viriplaca (Lepidoptera: Noctuidae) a long-distance migrant?

Area of Science:

• Entomology
• Agricultural Science
• Ecology

Background:

• Heliothis viriplaca (Hüfnagel) (Lepidoptera: Noctuidae) is a significant polyphagous pest affecting crops like beans, cotton, maize, and alfalfa globally.
• The migratory patterns of H. viriplaca in northern China, particularly its long-distance movements, were previously uncharacterized.

Purpose of the Study:

• To determine the seasonal migration patterns of Heliothis viriplaca in northern China.
• To investigate the influence of prevailing winds and monsoon airflows on H. viriplaca migration.

Main Methods:

• Conducted searchlight trapping and ovarian dissection on an isolated island in the Bohai Strait from 2003 to 2014.
• Analyzed trapped insect numbers, yearly and monthly variations, and female mating rates and ovarian development.

Main Results:

• Confirmed long-distance migration of H. viriplaca, driven by East Asian monsoon airflows.
• Observed a regular seasonal migration pattern from May to October, with peak activity in summer (67.99 ± 6.54%).
• Migration was detectable for an average of 116.5 ± 5.6 days annually, with variations in duration.
• Early migrating females (May-June) exhibited higher mating rates and ovarian development than later ones (July-September), suggesting migration is not solely tied to the 'oogenesis-flight syndrome'.

Conclusions:

• Heliothis viriplaca exhibits predictable long-distance seasonal migration in northern China, influenced by monsoon winds.
• The findings provide crucial data for enhancing pest forecasting and management strategies for H. viriplaca.
• Migration timing and reproductive status suggest a complex migratory behavior not strictly dictated by immediate reproductive needs.