Life history, morphology and host choice among populations of blissus leucopterus hirtus montandon (Hemiptera: Blissidae) in Quebec and Atlantic Canada

Auld, Robyn (2012) Life history, morphology and host choice among populations of blissus leucopterus hirtus montandon (Hemiptera: Blissidae) in Quebec and Atlantic Canada. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Blissus leucopterus hirtus Montandon (Hemiptera: Blissidae) (hairy chinch bug), is a pest of turfgrass in Quebec and Atlantic Canada that causes considerable damage to turf and lawns. This research investigated the influence of environmental heterogeneity on the phenology, morphology and host preference of B. leucopterus hirtus. Populations of B. leucopterus hirtus in St. John's, NL displayed the lowest threshold for egg development and the highest rate of egg development compared with other regions across the insect's range, indicating environmental influence attributable to shorter and cooler summers in the St. John's region. This adaptation was also reflected in a more compact phenology compared to other regions. Cumulative Degree Days and Julian Days were both effective in predicting the appearance of 2nd instars, a critical milestone for pest managers in conducting appropriately timed pesticide application. -- There was no difference in tertiary sex ratio among sites at a local scale, but there was an greater number of males than females in Fall 2004 and 2005 compared to the sprang, suggesting differential mortality of dispersal. Wing form ratios varied at the local scale and over time, with an increase in brachypters over two years indicating increasingly established populations. Differences in habitat at the local and regional scale were sufficient to produce differences in insect size, with the smallest insect size rankings in St. John's, NL, where egg development rates were also most rapid. -- Differences in host choice among 1st instars of B. leucopterus hirtus were observed at the local and regional level, demonstrating flexibility in host choice among populations. Preference was affected by age of insect, with 1st instars favouring Kentucky bluegrass, while 5th instars were less discriminant. Tendency for aggregation in later instars appeared to influence choice. Based on these results, pest managers should be better able to predict host vegetation based on insect phenology and potentially apply alternative methods of control such a vacuuming when populations are likely to be found on specific host plants as a result of either feeding preference or other behaviour tendencies such as aggregation. -- The results of this thesis confirm the influence of environmental heterogeneity on the phenology, morphology and host preference of B. leucopterus hirtus and the subsequent need for regional specificity in pest management, along with consideration of insect age and populations dynamics in host choice research.

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