Duration of paternal care in pine engraver beetles: why do larger males care less?

Dynamics of pheromone production and communication in the mountain pine beetle, Dendroctonus ponderosae Hopkins, and the pine engraver, Ips pini (Say) (Coleoptera: Scolytidae)

“…Large body size confers enhanced survivorship, dispersal ability, pheromone production capacity and breeding opportunities (Reid 1962(Reid , 1963Atkins 1967;McGhehey 1971;Thompson and Bennett 197 1;Amman 1972;Safranyik 1976;Amman and Cole 1983;Gnes 1985;Reid and Roitberg 1994;Robertson and Roitberg 1998). Based in part on my results, a hypothetical sequence of events portraying dispersal, host selection, mate choice, attack dynarnics and reproductive success in D. ponderosae in relation to size, is depicted in Figure 18.…”

“…Thus low amounts of aggregation pheromone should be sufficient to allow aggregation to occur. However, once an optimum attack density is reached, it is detrimental to the successful colonisers to recmit more beetles to the tree, as it will jeopardise their fitness (Cole 1973 Robertson and Roitberg 1998). It will still be an advantage to dispershg beetles to colonise the attacked tree as they may yet find mates and reproduce -albeit with relatively few offspnng.…”

“…Large male 1. pini sire more offspnng and have better breeding opportunities than small ones (Reid and Roitberg 1994; Robertson and Roitberg 1998). Females active1 y prospect for males during aggregation on a log and it is hypothesised that a strong pheromonal message released by large males would be a reliable indicator of male genetic quality (Miller et ai.…”

“…Male choice is therefore important in the fitness of female 1. pini. Although large males have high reproductive success (Reid and Roitberg 1994;Robertson and Roitberg 1998) and Reid (1992) inferred that female L pini appeared to prefer large males, Teale et al (1994) demonstrated that instead of king size based, assortative mating in 1. pini was based on enantiomeric specificity. Therefore, enantiomenc specificity may be the primary determinant of mate choice, followed by some other unmeasured trait that may confer fitness (Teale et al 1994).…”

Effects of host quality parameters on fitness of the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae).

“…Smaller mountain pine beetles have been shown to construct shorter galleries, lay fewer eggs, and lay their eggs at a slower rate than larger beetles . Large Ips pint (Say) beetles have been shown to be more successful at breeding in nature than smaller beetles (Robertson & Roitberg 1998).…”