Relative Yield Loss From Stem Borers (Lepidoptera: Crambidae) and Rice Water Weevil (Coleoptera: Curculionidae) in...

Area of Science:

• Agricultural Entomology
• Crop Science
• Pest Management

Background:

• The rice water weevil (Lissorhoptrus oryzophilus) is a major economic pest of rice in the U.S.
• Stem borers, like the Mexican rice borer (Eoreuma loftini), are increasing pest concerns in rice-producing regions.
• The impact of stem borer feeding, indicated by whiteheads, on rice yield loss requires further understanding.

Purpose of the Study:

• To determine the relative yield losses caused by L. oryzophilus and E. loftini in rice.
• To investigate the combined effects of these two pests on rice yield.
• To establish a relationship between whiteheads and yield loss.

Main Methods:

• Field trials were conducted in Louisiana from 2019-2020.
• Selective insecticides were used to manipulate pest infestations.
• Linear regression analysis was employed to correlate whiteheads with yield loss.

Main Results:

• L. oryzophilus caused greater yield losses than E. loftini in early-planted rice.
• In late-planted rice with high E. loftini populations, yield losses were comparable between the two pests.
• No additive impacts of concurrent L. oryzophilus and E. loftini infestations were observed.
• Each whitehead per square meter was associated with a 1.7% yield loss.
• Protecting rice from L. oryzophilus in the main crop improved ratoon crop yield.

Conclusions:

• Effective management of L. oryzophilus remains crucial for preventing economic losses in rice.
• E. loftini control benefits may be limited, with economic justification primarily in high-infestation scenarios like late-planted fields.
• Understanding pest-specific yield loss dynamics is essential for targeted pest management strategies in rice production.