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Slide 1: Rice water weevil life cycle. Adults are grayish-brown weevils (1/8 inch long) with a dark brown V-shaped mark on their back. Adults fly into rice fields and begin feeding on the leaves of rice plants. Rice water weevil life cycle, Adults are grayish-brown weevils (1/8 inch long) with a dark brown V-shaped mark on their back. Adults fly into rice fields and begin feeding on the leaves of rice plants. Male and female RWW adults mate and then females deposit eggs in the leaf sheath at or below the waterline. White larvae emerge from eggs in about one week and develop through four instars while feeding on rice plant roots. Larvae pupate in cocoons that are covered with a compact layer of mud and are attached to rice roots. The life cycle from egg to adult takes about one month.
Credits: created by A. Meszaros, pictures: J. Saichuk and R. M. Riggio.
Slide 2: Rice water weevil adult.
Photo Credit: J. Saichuk.
Slide 3: Rice water weevil adult.
Photo Credit: J. Saichuk.
Slide 4: Feeding scars. Feeding scars caused by rice water weevil adults.
Photo Credit: J. Saichuk.
Slide 5: Feeding scars. Feeding scars caused by rice water weevil adults.
Photo Credit: A. Meszaros.
Slide 6: Feeding scars. Feeding scars caused by rice water weevil adults.
Photo Credit: J. Saichuk.
Slide 7: Rice water weevil adult mating pair. Rice water weevil adult mating pair on rice leaf.
Photo Credit: J. Saichuk.
Slide 8: Missing stands in rice field. Missing stands in rice field, probably due to heavy rice water weevil infestation.
Photo Credit: A. Meszaros.
Slide 9: Heavily pruned rice roots. Heavily pruned rice roots due to rice water weevil larvae feeding (left) versus healthy rice roots (right).
Photo Credit: J. Saichuk.
Slide 10: Rice water weevil eggs. Microscopic picture of rice water weevil eggs in rice leaf sheet.
Photo Credit: R. M. Riggio.
Slide 11: Rice water weevil larvae. Microscopic picture of rice water weevil larva, feeding on rice roots.
Photo Credit: R. M. Riggio.
Slide 12: Steps of collecting/processing core samples. Steps of collecting core samples to estimate rice water weevil infestation. 1-2: Collecting core samples across the field. 3: Washing off the mud from the roots. 4: clean rice plant. 5: counting rww larvae. 6. Bucket with floating larvae in salt water.
Photo Credit: N. Hummel.
Slide 13: Rice water weevil larvae. Rice water weevil larvae are floated in salt solution. Each yellow circle surrounds a rice water weevil larva. The root tips (red arrow) are similar in appearance, but lack the ridged segmentation of larvae. The larvae are counted and sized as small, medium, large to assess the relative stage of development.
Photo Credit: N. Hummel.
Slide 14: Rice water weevil larvae. Floating rice water weevil larvae in a salt solution.
Photo Credit: J. Saichuk.
Slide 15: Rice water weevil larvae. Floating rice water weevil larvae in a salt solution.
Photo Credit: J. Saichuk.
Slide 16: Rice water weevil pupal case. Rice water weevil pupal cases on rice plant roots.
Photo Credit: J. Saichuk.
Slide 17: Rice water weevil pupal case 2. Rice water weevil pupal case on rice plant roots.
Photo Credit: J. Saichuk.
Slide 18: Rice water weevil pupal case 3. Rice water weevil adult emerging from pupal case.
Photo Credit: J. Saichuk.
