Feeding and oviposition preferences of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) on six Brassicaceae host plant species

Plutella xylostella (diamondback moth, DBM) is a globally distributed Lepidopteran that feeds and oviposits almost exclusively on plants in the Brassicaceae family. DBM disperses from the southern United States and Mexico into Canada in the spring and summer. Establishment of DBM in Ontario is partially dependent upon the quantity and quality of host plants available and the preference of DBM for different hosts. Host plants include many crops such as broccoli, canola and cabbage, as well as landscape ornamentals and wild plants. It has previously been established that DBM are attracted to host plants by chemicals, specifically glucosinolates. I examined the preference of DBM among crop, wild and ornamental host plant species and how preference varies with insect life stage (3rd and 4th instar larvae and adults). Experiments included exposing DBM larvae from five populations coming from different locations in Canada to six Brassicaceae species and evaluating the preferences and weight gain over one hour. Then adult females were exposed to these same plant species and their oviposition preferences were examined. Populations from Alberta, Saskatchewan and Ontario were compared to assess differences in preference associated with geographic region or species of host plant. The ultimate goal of my study was to understand the potential of various Brassicaceae species to act as reservoirs to sustain and promote population growth of DBM, as well as sinks that may decrease DBM abundance. Results showed that garden cress (Lepidium sativum) was highly preferred over other species (wintercress, black mustard, aubretia, broccoli and ornamental kale) for both food and oviposition sources. Previous studies report that garden cress contains saponins, chemicals shown to be toxic to developing DBM larvae, however no studies have yet shown a preference for garden cress. These results provide information on a novel host plant with the potential to control DBM population growth. No difference in preferences was found among populations of DBM from various sources in Canada.

The Rapids, Niagara

The description of the image reads "No. 115 - The Rapids, Niagara - From the Terrapin Tower". On the reverse it reads "The Rapids, Niagara, From the Terrapin Tower (taken instantaneously). From this commanding point of view the rapids are seen to great perfection - the Tower standing just on the edge of the Horse-shoe Fall. Some idea of the rapidity with which these waters hurry onward to the mighty abyss may be formed from the fact that the river descends nearly fifty-one feet in a distance of three-quarters of a mile. Gathering force as they approach nearer the edge of the Falls, they dash and foam amid the rocks which speck their surface, and with torturous writhes dash onward with a fury grand and beautiful in the extreme. Whole flocks of water-fowl have often been seen going to destruction among these rapids. Pleased with being carried by the stream, they have indulged in the pleasure till the rapidity of the current has rendered it impossible for them to rise and thus have they been carried down and washed over the Fall. At one time during the months of September and October, sufficient quantities of dead water-fowl have been found every morning below the Fall to afford ample subsistence for the garrison at the fort. The bodies of bears, deer, and other animals have also been found."