The growth and survival of Panolis flammea larvae in the absence of predators on Scots pine and lodgepole pine

Abstract

1. The survival, growth and development of larvae of the pine beauty moth, Panolis flammea (D & S ) (Lepidoptera: Noctuidae) were examined as part of a study to determine (i) why damaging outbreaks of this insect in Scotland are frequent on lodgepole pine but do not occur on Scots pine, and (ii) why outbreaks are associated with areas of deep unflushed peat.2. Larvae were studied inside predator exclusion cages on mature pine trees in Elchies forest where a major infestation occurred in 1978-79.3. Surprisingly, larval survival was generally greatest on Scots pine and lowest on lodgepole growing in deep peat. Also, larval growth and development were greater on Scots than lodgepole pine and were unaffected by the type of soil in which the lodgepole pine was growing.4. Larval performance was generally better on lodgepole pine that had been thinned and received fertilizer. 5. Larval survival was affected by pine shoot stage during egg hatch in one of the two years in which this was examined.6. Observations on P.flammea pupae were confused by disease, parasitism and probably by differences in weight loss caused by differences in larval development. Parasitism by ichneumonid parasitoids was recorded on Scots pine but not on lodgepole pine. 7. It was concluded that (i) the absence of pine beauty moth outbreaks on Scots pine, and (ii) the occurrence of outbreaks on lodgepole pine growing in deep unflushed peat were not the result of lodgepole pine growing in deep peat being a more suitable host plant than lodgepole pine and Scots pine growing elsewhere. It seems more likely that the observed outbreak behaviour of P.flammea in Scotland is associated with differences in predation and parasitism in plantations of difference host plants and in plantations of lodgepole pine growing in different soils.

Changing dynamics of the pine beauty moth (Panolis flammea) in Britain: the loss of enemy free space?

“…1A ). This confirmed previous studies ( Watt, 1989b;Watt et al , 1991 ;Leather et al , 1998). Hicks et al .…”

“…Scots pine is a better host nutritionally for P. flammea , ( Watt, 1989a, although there is no evidence to indicate that these factors affect adult fecundity or rate of oviposition ( Watt, 1989b ). Predation, parasitism and disease affect the host-associated population of P. flammea differently.…”

“…Predator exclusion experiments by Watt (1989b) showed that P. flammea located in Scots pine sites suffered more predation than those in lodgepole pine sites. Before this time, natural enemies were not thought to affect P. flammea populations significantly.…”

Are differences in life history parameters of the pine beauty moth Panolis flammea modified by host plant quality or gender?

“…Scots pine (P. sylvestris) is the native host plant (Watt & Leather, 1988) and is considered to be a good quality host for P. flammea (Watt, 1987(Watt, , 1989. Scots pine (P. sylvestris) is the native host plant (Watt & Leather, 1988) and is considered to be a good quality host for P. flammea (Watt, 1987(Watt, , 1989.…”

“…The three host plants used in this study were intended to represent food of differing quality to the P. flammea larvae. Scots pine (P. sylvestris) is the native host plant (Watt & Leather, 1988) and is considered to be a good quality host for P. flammea (Watt, 1987(Watt, , 1989. Lodgepole pine (P. contorta) on the other hand, has been introduced from North America only relatively recently (Lines, 1966).…”