STRUCTURE AND FUNCTION OF THE SENSILLA ON THE ANTENNAL CLUB OF THE SOUTHERN PINE BEETLE, DENDROCTONUS FRONTALIS (ZIMMERMAN) (COLEOPTERA: SCOLYTIDAE)

by Dr. Molly Darr | Jun 15, 2022 | 1971-1980 Publications

Abstract

Four types of sensilla occur on the antennal club of Dendroctonus frontalis: fluted sensilla, sensilla trichodea II and III and sensilla basiconica. All but the sensilla trichodea III have cuticular pores. Electrophysiological studies show the sensilla trichodea II and basiconia to be olfactory sensitive hairs for beetle and host tree-produced volatiles. The sensilla trichodea III are mechanosensitive hairs. Electrophysiological data were not obtained for the fluted sensilla. The morphologies of the 4 sensillar types are described.

Keywords

Olfactory sensilla, bark beetle, pheromone, host odor.

To read the full article please visit the link below:

BARK BEETLE OLFACTION: PHEROMONE RECEPTOR SYSTEM’ IN DENDROCTONUS FRONTALIS

by Dr. Molly Darr | Jun 15, 2022 | 1971-1980 Publications

Abstract

Differential adaptation of antennal olfactory acceptors and electroantennogram (EAG) techniques were used to describe the acceptor population for pheromones and host compounds. All acceptors appeared to have some degree of specificity for the pheromone, frontalin. This conclusion was verified by both EAG and single unit recordings. The oxygen containing pheromones occupied a larger percentage of the acceptors than the hydrocarbon host tree terpenes. Pheromones produced by one sex occupied a larger percentage of the pheromone acceptors in the opposite sex. Single unit recordings indicated a chiral acceptor. (-) Exo-brevicomin stimulation elicited a greater number of impulses in the cells recorded than equal quantities of the (+ )-enantiomer. Electrophysiologica] data correlated well with behavioral roles attributed the compounds tested.

To read the full article please visit the link below:

Production Flow System Evaluation of Within-tree Populations of Dendroctonus frontalis (Coleoptera: Scolytidae)

by Dr. Molly Darr | Jun 15, 2022 | 1971-1980 Publications

Abstract

Production flow system methodologies, originally developed for use in industrial quality control and electrical engineering problem solving, were adopted for use in describing the partial within-tree population system of Dendroctonus frontalis. The spatial and statistical distribution of D. frontalis life stages were defined by 2 and 3 parameter non-linear mathematical models. By integrating under the curves generated by the models for the various life stages it was possible to quantitatively define within-tree populations of the various life stages. For each year of study, transition probabilities between life stages were calculated using standard production flow system techniques. These transition probabilities were cast into a production flowgraph format. Each of the production flow models was evaluated using an algebraic solution technique and the similarities and differences between populations occurring in the 3 yr of study were contrasted. The production flow system technique was suggested as an alternative to the traditional life table format. Several advantages of the production flow system format over the life table were suggested. The most important advantage was that the variables are tied together mathematically and cast into a formalized engineering methodology.

To read the full article please visit the link below:

Interspecific Competition Between Monochamus titillator and Dendroctonus frontalis

by Dr. Molly Darr | Jun 15, 2022 | 1971-1980 Publications

Abstract

Interspecific competition was hypothesized to exist as a result of foraging by Monochamus titillator Fabricius in the sub-cortical region of loblolly pines attacked by Dendroctonus frontalis Zimmerman. The existence of the interaction was demonstrated experimentally; first by defining the distributional pattern of D. frontalis progeny adults in samples of bark in which M. titillator foraging was absent. Next, using data in which foraging occurred the observed number of D. frontalis inside the foraged area was compared with the expected number if no foraging were present. The observed and expected values were demonstrated to come from different distributions which substantiated the existence of competition. The specifications for developing mathematical models of the competitive process included consideration of the extent and distribution of M. titillator foraging over the entire bole of the tree and D. frontalis density in the infested portion of the tree bole. The form of the data used in model development was appraised from the standpoint of providing the most realistic account of the process under consideration and the results of the use of unmanipulated data were compared with 2 separate types of manipulations commonly employed in the analysis of bark beetle populations. A series of nonlinear mathematical models based on unmanipulated data was developed which provides the expression of mortality resulting to D. frontalis as a consequence of M. titillator foraging as weI! as a survivorship model. These models include a definition of the following components: the relationship between the expected number of D. frontalis in the area foraged by M. titillator [E(SPB1)] and the normalized tree bole (obtained by dividing the sample height, S.H., by the infested bole height, I.B.H.); the difference between observed number of D. frontalis in the foraged area (SPB1) and E(SPB1) = Δ (SPB1) and S.H./I.B.H.; the relationship between the area foraged by M. titillator A1 and S.H./ I.B.H.; the relationship between Δ SPBl and A1, which is the mortality expression; and the relationship between (SPB1) / E(SPB1) and A1, which is the survivorship expression.

The object of competition between the 2 species is the limited area of inner-bark necessary for development of both species. The form of the competitive process contains elements of both interference and exploitation.

To read the full article please visit the link below:

Response of Heydenia unica (Hymenoptera: Pteromalidae) to Dendroctonus frontalis (Coleoptera: Scolytidae) Pheromones and a Host-Tree Terpene

by Dr. Molly Darr | Jun 15, 2022 | 1971-1980 Publications

Abstract

Heydenia unica Cook & Davis, a larval parasite of the southern pine beetle, Dendroctonus frontalis Zimmerman, was attracted in significant numbers to olfactometers baited with the beetle pheromones and a host- tree terpene. The host-tree terpene, a-pinene, attracted considerably more H. unica than did the individual pheromones, which did not attract significantly more than the control.

To read the full article please visit the link below: