Field Crops News

Ant Predation of June Beetle Eggs in Maize (Corn)

A study of June beetle (Phyllophaga) egg predation was recently conducted in adjoining no-till and conventional-till maize (corn) fields in Honduras. The study sought to answer why fewer June beetle larvae (white grubs) were present in the no-till field. Egg predation was measured, and egg predators were identified, by placing Phyllophaga eggs behind buried Plexiglas observation plates. Pitfall traps were used to determine the number and species of ants in the two fields. The Plexiglas observations revealed significantly more egg predation in the no-till field and identified ants as the predominant, if not sole, predator of these eggs. Over 33% of eggs placed in the ground were taken within 24 hours. All observed predation was done by three species of ants, Solenopsis geminata, a second small (<1 mm long) Solenopsis sp., and a species of Pheidole. The greatest number were taken by S. geminata. Pitfall trap samples yielded significantly higher numbers of ant species in the no-till system, as well as a greater number of total ants. Numbers of S. geminata also were significantly higher in the no-till system , while numbers of the Pheidole sp. were not significantly different. The other Solenopsis sp. was not found in any pitfall trap samples. These results show that ants are key predators of Phyllophaga eggs, and that more egg predation occurs in no-till than in conventional-till maize. The results also suggest that the fewer number of white grubs in the no-till maize may be due to greater egg predation.

- John Zenger, Purdue University

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