Adaptation in an insect host–plant pathogen interaction

Abstract

Selection on parasites to adapt to local host populations may be direct or through other components of the system such as vectors or the food plant on which the parasite is ingested. To test for local adaptation of nucleopolyhedrovirus among island populations of western tent caterpillars, Malacosoma californicum pluviale, we compared virus isolates from three geographically distinct sites with different dominant host plants. Pathogenicity, speed of kill and virus production of each isolate were examined on the three food plants. Virus isolates from the two permanent host populations had the fastest speed of kill on the host plant from which they were isolated. This was not the case for a caterpillar population that goes extinct when populations are regionally low. Virus isolates on some plant species combined rapid speed of kill with high virus yield. Infection of hosts by mixed microparasite populations could facilitate local adaptation in response to differing food plant chemistry.

Genotypic and phenotypic diversity of a baculovirus population within an individual insect host

“…In the case of PaXNPV there is preliminary evidence that the plant on which the insect host feeds could inXuence baculovirus phenotype (Hodgson et al, 2002b). This is supported by recent data from another system, the western tent caterpillar, Malacosoma californicum pluviale (Dyar), and its NPV, in which Weld-collected virus isolates have been shown to be adapted to the locally abundant host plant (Cory and Myers, 2004).…”

Fungal entomopathogens in a tritrophic context

“…Therefore the possibility exists that plants could influence the survival and thus selection of certain fungal strains. There is some evidence in another entomopathogeninsect system that baculoviruses become adapted to the host plant on which their insect host feeds (Cory and Myers 2004). This is particularly likely to occur if the pathogen spends extended time periods on the plant surface between host generations.…”

Insecticidal Efficacy of Azadirachta indica, Nucleopolyhedrovirus and Chlorantraniliprole Singly or Combined against Field Populations fo Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

“…The purified virus was given washes three times in distilled water, and held in 0.1 mM NaOH at 5 °C. Polyhedral occlusion bodies (POB) in 1 mL suspension was recorded 10 times using haemocytometer (Cory and Myers, 2004). The formulation was applied (2.1 × 10 5 POB mL -1 ) on both sides of surface sterilized tomato leaf discs and air dried.…”