Influence of entomopathogenic fungi from forest and urban habitats on founding pairs of reticulitermes flavipes (rhinotermitidae)

Abstract

In forest habitats, termites break down woody debris and assist in nutrient cycling of carbon and nitrogen. However, infestations in suburban habitats have given subterranean termites a high priority for pest management. Biological control of subterranean termites has been unsuccessful using entomopathogenic fungi, such as Beauveria and Metarhizium. Previous biocontrol research focused mostly on the worker caste and exploiting social behaviors. Due to many social and physiological defenses, large termite colonies survive fungal invasions. This research focused on founding pairs of primary reproductives when colonies are smallest and there are only two termites. Because most termite colonies invading newer homes in Missouri are started by Reticulitermes flavipes primary kings and queens, control of founding pairs by preventing establishment may be an important method of termite control. Using locally collected Beauveria and Metarhizium, this research compared mortality and sublethal effects on founding pairs by exposure to fungal spores from forest and urban habitats. Behavior of founding pairs in the presence of any spores and fungistatic effects of founding pair head and abdomen extracts on spore germination were also examined. Forest Beauveria spores were more virulent than Metarhizium spores when founding pairs were examined in a no-choice bioassay. Sublethal effects on egg laying were also observed. When founding pairs where given a choice to nest in areas with or without spores, Metarhizium spores were more virulent. Metarhizium germination was not affected in the presence of imago body extracts. Beauveria germination decreased in the presence of imago head extracts but increased in the presence of imago abdomen extracts.