What is rindworm? Investigating a poorly understood pest complex in watermelon

Area of Science:

• Agricultural Entomology
• Horticultural Science
• Pest Management

Background:

• Watermelon (Citrullus lanatus) cultivation faces numerous arthropod pests, with research primarily addressing leaf and root feeders.
• Pests causing fruit surface damage, termed "rindworm," are poorly understood despite economic implications.

Purpose of the Study:

• To survey arthropod populations and quantify rind damage in commercial Indiana watermelon fields over two years.
• To assess the economic impact of rind damage on watermelon marketability.

Main Methods:

• Conducted a two-year survey across 32 commercial watermelon fields.
• Performed visual surveys and photographic analysis to quantify rind blemish extent on over 10,000 melons.
• Correlated pest population densities with observed rind injury.

Main Results:

• Approximately 9% of surveyed melons exhibited insect feeding damage.
• An estimated 14.9% of harvests were at risk of marketability loss due to rind injury.
• Damage was significantly higher on the underside of fruits, on melons grown on soil versus plastic, and in field centers versus edges.

Conclusions:

• "Rindworm" represents an economically significant and understudied pest issue in watermelon and cucurbit production.
• Management strategies must consider the protected feeding location of these pests.
• Timing of insecticide applications is crucial for mitigating late-season crop losses.