Nutritional status and feeding behavior of in situ populations of the German cockroach, Blattella germanica (L.)

Stephen Ashley Kells, Purdue University

Abstract

Nutritional status affects diet selection and foraging behavior of German cockroaches, and must be considered when employing traits to control infestations. Nutritional status of cockroaches in situ was estimated by analyzing physiological indicators in response to varying levels of dietary nutrients. Available dietary protein (7 to 9% $\pm$ 3%) for German cockroaches in infested apartments was significantly less than the 25% ($\pm$2%) estimated for cockroaches held in the laboratory and provided a commonly used rearing diet, rodent chow. The estimated ratio of dietary fat:carbohydrate (0.8 $\pm$ 0.4 to 1.35 $\pm$ 0.6) used by in situ cockroaches was significantly higher than individuals provided rodent chow (0.25 $\pm$ 0.14). German cockroaches in situ have an available diet of low protein, low carbohydrate and high fat, which differs from the nutrient regime typically provided to laboratory colonies. To determine stress imposed by the in situ diet, nutrient selection and foraging behavior were examined using cockroaches provided rodent chow or a diet reflecting in situ. When given a choice among protein, carbohydrates and fat, cockroaches previously fed rodent chow tended to select fat or protein, whereas cockroaches fed the in situ diet elevated protein consumption. Individuals who increased protein consumption tended to decrease consumption of carbohydrates at particular nutrient concentrations, but consumption of fat was stable regardless of previous diet and concentration. Cockroaches fed in situ or rodent chow diets were also evaluated for their foraging behavior. Cockroaches tended to forage for food items based on a hierarchy of diet selection, then distance in relation to harborage. Individuals provided the in situ diet altered foraging patterns depending on location of protein sources, while cockroaches fed rodent chow altered foraging behavior depending on the placement of carbohydrate sources. These results have implications for further research involving cockroach nutrition and behavior, as well as insecticidal bait placement and formulation.

Degree

Ph.D.

Advisors

Bennett, Purdue University.

Subject Area

Entomology|Ecology|Anatomy & physiology|Animals

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