Effect of temperature and resin on hatch of eggs of the mountain pine beetle (dendroctonus ponderosae)
TL;DR: Effects of temperature and resin on hatch of mountain pine beetle eggs were investigated, but direct contact with liquid resin greatly reduced egg hatch.
Abstract: Effects of temperature and resin on hatch of mountain pine beetle eggs were investigated. Per cent hatch was related to total degree-hours above 40°F, the average being 5113 for 50% hatch under field conditions. Average supercooling point was 1.3°F. Higher temperatures in the freezing range were lethal with long exposure. Atmosphere saturated with volatiles from liquid resin had very little effect on egg hatch, but direct contact with liquid resin greatly reduced egg hatch.
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TL;DR: Scolytid bark beetles that colonize living conifers are frequently associated with specific fungi that are carried in specialized structures or on the body surface, suggesting that there is mutual benefit to the fitness of both beetles and fungi.
Abstract: Scolytid bark beetles that colonize living conifers are frequently associated with specific fungi that are carried in specialized structures or on the body surface. These fungi are introduced into the tree during the attack process. The continuing association suggests that there is mutual benefit to the fitness of both beetles and fungi. The fungal species may benefit from the association with the beetles by transport to new host trees. Beetle species may benefit from the association with fungi by feeding on the fungi, or by the fungi contributing to the death of the host trees through mycelial penetration of host tissue, toxin release, interactions with preformed and induced conifer defenses, or the combined action of both beetles and fungi during colonization. Extensive research has been directed towards characterizing the interactions of beetle-fungal complexes with live host conifers and determining the ecological advantages for maintaining the associations. However, differences among systems and how species interact under different population and environmental conditions make it difficult to generalize about the importance of the separate biological components in successful host colonization.
757 citations
Cites background from "Effect of temperature and resin on ..."
...Also, components of preformed resins can be toxic or repellent to colonizing beetles (73, 196, 202, 221), although beetles are generally more tolerant of host resins than nonhost resins (220)....
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TL;DR: The colonization sequence reflects the outcome of a dynamic interaction between the tree and the initial "pioneer" beetles, and ensures that the attack will terminate once the tree has been rendered suitable for brood development and, thus, minimizes the deleterious effect of intraspecific competition.
Abstract: Unlike most phytophagous insects, the reproduction of primary bark beetles (Coleop- tera: Scolytidae) is contingent on host mortality. Consequently, there have been intense selective pressures on trees for properties which confer resistance to attack, and likewise, on the insect for increased behavioral complexity by which to overcome these defenses. In this study, we examined the relationship between the physiology of Pinus contorta var. latifolia and the behavior of the bark beetle, Dendroctonus ponderosae. Host mortality is a discrete outcome which is contingent on the quantitative interaction between host resistance and beetle numbers. At low attack densities, trees respond by confining beetles and their associated fungi within necrotic lesions containing toxic or inhibitory compounds. Beyond a critical "threshold of attack," however, the defensive capacity of the tree is exhausted, and mortality occurs. This threshold occurred at -40 galleries/m2 in our experimental stands. The reproductive success of the bark beetle is directly related to the depletion of host defenses through concentrated attack. At sufficiently high attack densities, -80 galleries/M2, the potential suppressive effect of the host on brood development is not manifested. Increased beetle numbers, however, cause an exponential decline in brood production due to intraspecific competition. Conse- quently, there is an optimal density, =62 attacks/M2 at which reproduction and survival of the beetle is maximized. Dendroctonus ponderosae utilize defensive secretions as precursors and synergists of aggregation pheromones, and thereby, elicit maximum responses from flying beetles while the host's production of toxins is at its maximum. This mechanism also ensures that the attack will terminate once the tree has been rendered suitable for brood development and, thus, minimizes the deleterious effect of intraspecific competition. Such an interaction, in which all trees could theoretically be colonized regardless of their resistance capacity, cannot result in a stable host-parasite system. Conifers, however, seem to be able to interfere with bark beetle communication. Pheromone synthesis within the hindgut and emission from the entrance site are distinct events, and beetles contained within a copious flow of resin seem unable to elicit attraction. This ability to interrupt the beetles' communication sequence, however, is in- versely related to the number of beetles initiating localized attacks. Consequently, the colonization sequence reflects the outcome of a dynamic interaction between the tree and the initial "pioneer" beetles.
667 citations
01 Jan 1974
TL;DR: Rodent distribution and abundance in relation to season, habitat, and cover solely in agricultural habitats of Vigo County, Indiana was investigated in this paper, and the specific objective of this report is to relate those findings to explain the occurrence of these rodents in cultivated field ecosystems and to compare their results with those of previous studies to determine what changes, if any, have occurred in the distribution and abundances of these animals in cultivated fields.
Abstract: rodent distribution and abundance in relation to season, habitat, and cover solely in agricultural habitats of Vigo County, Indiana. The specific objective of this report is to relate those findings to explain the occurrence of these rodents in cultivated field ecosystems and to compare my results with those of previous studies to determine what changes, if any, have occurred in the distribution and abundance of these rodents in cultivated field ecosystems.
648 citations
TL;DR: Experimental studies in the Pacific Northwest and the southeast U.S.A., and in Norway, are drawn upon to show that tree resistance to attack may be closely related to the amount of current and stored photosynthate that is available for defense.
479 citations
01 Jan 2006
403 citations
References
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TL;DR: The principles of insect cold-hardiness will be discussed under three main headings : (a) chilling and cold-acclimation, (b) avoidance of freezing by supercooling, and (c) freezing-tolerance.
Abstract: Cold is a relative term which for present purposes will be considered to encompass temperatures too low to support normal development of the in sects concerned. The effects of cold on insects may be manifold, but a pri mary distinction must be made on the hasis of whether freezing does or does not result. The dividing line, however, is seldom at the freezing point of the tissues but rather at the supercooling point, for insects almost invariably supercool to some extent, usually many degrees. Cooling without freezing has been termed "chilling" (9), particularly when the emphasis is on temperatures above O°C. Such investigations usually deal with i nsects that do not normally encounter cold, e.g., household pests. Unaccustomed to cold, they tolerate it poorly. On the other hand, insects that hibernate in temperate and colder climates must tolerate a wide range of low temperatures, often for long periods. Some species improve their toler ance through processes of cold-acclimation and cold-hardening. All insects supercool to some extent, regardless of need; in fact, some that need to do so least supercool below -40°C. Most hibernating insects do need to supercool, however, to avoid freezing, which would be fatal; the remainder have not this need because freezing is not injurious to them. The former group are called freezing-susceptible and the latter freezing-resistant or freezing-tolerant (34). The principles of insect cold-hardiness will be discussed under three main headings : (a) chilling and cold-acclimation, (b) avoidance of freezing by supercooling, and (c) freezing-tolerance.
632 citations
TL;DR: The reaction in lodgepole pine in response to attack by Dendroctonus ponderosae and subsequent infection by blue stain fungi varies with the degree of resistance manifested by the tree.
Abstract: The reaction in lodgepole pine in response to attack by Dendroctonus ponderosae and subsequent infection by blue stain fungi varies with the degree of resistance manifested by the tree. In both res...
265 citations
TL;DR: Evidence gathered from various diapausing species showed that glycerol accumulated during the fall, and an increase in concentration was observed in eggs of one species at temperatures ranging from −5° to 20 °C.
Abstract: The effects of glycerol on cold-hardiness in insects and seasonal changes in glycerol concentrations were investigated. The presence of this polyhydric alcohol was demonstrated in overwintering sta...
227 citations
TL;DR: A study of the biology of the mountain pine beetle was made by the writer from 1955 to 1960 in several small outbreak areas near Invermere, British Columbia, and describes the life cycle, brood development, and flight periods.
Abstract: The importance of the mountain pine beetle to the pine forests of North America has been pointed out by several writers (Hopkins, 1909; Swaine, 1918; Evenden et al., 1943; Hopping and Mathers, 1945). Its range covers parts of southern British Columbia and Alberta, Idaho, Montana, Wyoming, Oregon, Washington, California, Utah, and Nevada. The size of populations and the damage vary from year to year. A study of the biology of the mountain pine beetle was made by the writer from 1955 to 1960 in several small outbreak areas near Invermere, British Columbia. (50°30′ N. lat., 116°00′ W. long., 2740 feet above sea level). The host tree in these areas was lodgepole pine, Pinus contorta Douglas var. latifolia Engelmann. The results of the study will be presented in three parts. Part I is presented herein and describes the life cycle, brood development, and flight periods. Part II is a discussion of the behaviour of the adult as affected by physical factors operating under the bark. Part III describes the interaction of the insect and its host, with special reference to mortality and brood survival.
112 citations
TL;DR: The influence of bark moisture and temperature on the hehaviour of the egg-laying female within the host will be discussed, as well as internal changes associated with the behavioural pattern.
Abstract: This paper deals with the influence of bark moisture and temperature on the hehaviour of the egg-laying female within the host. Fecundity of the insect will he discussed, as well as internal changes associated with the behavioural pattern. The life-cycle, brood development, and time of flight was described in Part I of the present series. The behaviour during mating, egg laying, and gallery construction were described earlier (Reid 1958b).
79 citations