Miki Furuya

Degree Name

Master of Science (MS)

Semester of Degree Completion

1992

Thesis Director

Kipp C. Kruse

Abstract

I quantified the oxygen requirements of developing eggs and the adaptive significance of male brooding behavior in the giant waterbug (Belostoma flumineum). Egg pads brooded by males, and egg pads experimentally removed from the dorsa of males and maintained in a metabolic shaker, were tested for hatching success in four oxygen treatments (5%, 8%, 10% and 21%-control) in a closed laboratory system. All of the control male brooded egg pads, and 100% of the eggs/pad, hatched whereas none of the egg pads hatched in the 5% oxygen treatment. Fifteen of 20 (75%) male brooded egg pads in the 10% oxygen treatment hatched 98% of the eggs. Fourteen of 21 (66%) male brooded egg pads hatched an average of only 27% of the eggs/pad in the 8% oxygen treatment; eggs hatched from only the most peripheral three rows of the pad. Most (20 of 26 = 77%) of the male brooded egg pads that did not hatch in the hypoxic treatments were discarded by the male. None of the egg pads in the hypoxic treatments hatched eggs in the maleless experiment; in contrast, 24 of 27 (89%) of the control pads hatched 100% of the eggs/pad. Furthermore, eggs developed more slowly in hypoxic treatments than in controls. These results suggest that the adaptive significance of paternal care in B. flumineum can be attributed, at least in part, to hypoxic conditions commonly found in aquatic habitats inhabited by this species.

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