Upon emerging from the oval cell in which they completed development, adult female Dendroctonus ponderosae fly to a Pinus tree that is suitable for breeding and maintaining progeny. Here they build an egg gallery by burrowing straight through the bark of the tree and into its phloem. These females then secrete pheromones in order to attract male D. ponderosae to the site. The males, upon arrival to the site, secrete their own pheromones to attract both male and female beetles to the location, initiating a local infestation.
At this point, the males proceed to exhibit mate selection by preferentially choosing females whose egg galleries are of larger size but within smaller trees. Smaller males are more likely to enter galleries than larger males, most likely because of some kind of size-dependent sexual selection dependent on the females. Large females in turn show sexual selection by allowing larger males to enter their galleries much more quickly than smaller males. To enter the galleries, males must first stridulate (rub their legs together in order to produce a certain sound). Once a female grants access to the male, the male enters the gallery and fertilization occurs. The female will then lay approximately 75 eggs. Males will remain with the females anywhere from a few days to three weeks after fertilization occurs.
Mating System: monogamous
Adult mountain pine beetles leave the trees in which they developed during summertime; this is usually sometime during July or August, but could potentially be anytime from mid-June until the beginning of September. At this time, they seek out new trees in which to reproduce. Males fertilize females within these new trees, then females lay about 75 eggs. The eggs hatch into larvae within about 10 to 14 days. Although the parents might remain within the tree for a few days afterward, there has been no parental involvement observed in Dendroctonus ponderosae. Around June or July of the following year, after having developed within the egg gallery throughout winter, the eggs develop into pupae. The pupae then become sexually mature adults sometime around mid-August, and can then leave the Pinus tree to find a mate.
Breeding interval: Mountain pine beetles breed once yearly, or potentially every two years if temperatures are cooler.
Breeding season: Breeding season for mountain pine beetles is in July or August.
Average eggs per season: 75.
Range gestation period: 10 to 14 days.
Range age at sexual or reproductive maturity (female): 1 to 2 years.
Average age at sexual or reproductive maturity (female): 1 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
No parental involvement has been observed in Dendroctonus ponderosae.
Parental Investment: pre-fertilization (Protecting: Female)
- U.S. Department of Agriculture: Forest Service. Mountain pine beetle. Forest Insect & Disease Leaflet 2. Portland, Oregon: USDA Forest Service. 2009. Accessed July 03, 2011 at http://www.fs.fed.us/r6/nr/fid/fidls/fidl-2.pdf.
- Leatherman, D., T. Mehall, I. Aguayo. 2007. "Mountain Pine Beetle" (On-line). Colorado State University - Extension. Accessed July 03, 2011 at http://www.ext.colostate.edu/pubs/insect/05528.html.
- Reid, M., O. Baruch. 2010. Mutual mate choice by mountain pine beetles: size-dependence but not size-assortative mating. Ecological Entomology, 35:1: 69-76.