Dendroctonus frontalis Frontalin

R=OH). With less polar chloride substituents, however, the RhuA dia-stereoselectivity is reduced and a considerable fraction of the FucA configurated product (40%) is also formed. Interestingly, alkaline cyclization in the latter occurs with an inverse preference to furnish 177, which contains the enantiomeric bicyclic [3.2.1] structure shared by the FruA product 175 as well as by (S)-( — )-frontalin 178, the aggregation pheromone of the southern pine beetle Dendroctonus frontalis. 

What are some examples of these attractants (Figure 1) For mate finding, the insect-produced pheromones are the primary examples. However, environmental factors may also play an important role in the effectiveness of attractants. In the southern pine beetle, Dendroctonus frontalis. alpha-pinene released from an attacked tree is necessary along with the endogenously produced frontalin in order to attract males for mating (14). 

Frontalin (98, Figure 4.49) is the active component of the aggregation pheromone of the southern pine beetle (Dendroctonus frontalis), the western pine beetle (Dendroctonus brevicomis) and the Douglas-fir beetle (Dendroctonuspseudotsugae). Mori s 1975 synthesis of the enantiomers of frontalin via enantiomer separation (optical resolution) of an intermediate87 enabled their bioassay, and only (lS,5/ )-98 was bioactive as the pheromone component of D. brevicomis.32 A recent study on female D. frontalis revealed its (15, 5/C)-98 to be of about 91% ee.88... 

Frontalin (139) is known to be the aggregation pheromone of the southern pine beetle Dendroctonus frontalis. The biologically active form of this com-... 

In the related species, Dendroctonus frontalis, the compound frontalin (73) is primarily attractive to male bees and the female does not release a female attractant. The first males to arrive ingest resin and synthesize and release a male inhibitor, verbenone (65). It seems quite likely that the male beetles have the ability to convert a-pinene into verbenone. 

Recently, Payne (152) reported that frontalin (9), the sex pheromone of the bark beetle Dendroctonus frontalis, is also a kairomone which attracts its predator Thanasimus dubius. 

The significance of Soderquist s 9-oxa-10-borabicyclo[3.3.2]decyl (OBBD) derivatives obtained by selective oxidation of 9-BBN derivatives with TMANO is demonstrated in the synthesis of (S)-(-)-frontalin [6] (Scheme 31.2), the aggregation pheromone of the pine beetle Dendroctonus frontalis) by Suzuki coupling [7]. 

Aggregation of the southern pine beetle, Dendroctonus frontalis. .. on loblolly pine (Pinus taeda) under beetle attack was not disrupted by aerial application of frontalure, which is a mixture of the attractant pheromone frontalin (195) and the host terpene a-pinene (230). Instead, aerial saturation with the pheromone in a heavily beetle-infested pine forest resulted in a rapid increase in the aggregation of beetles on pine trees undergoing attack (549). In this experiment, a ten hectare section of pine forest including 1.6 hectares of a D. frontalis infestation was treated twice by aircraft with rice seed soaked with frontalure. This formulation released virtually all of the frontalure within 24 hr (45 g/ hectare for the first application and 450 g/hectare for the second). 

The frass of females of the western pine beetle Dendroctonus brevicomis is enriched with endo- (XIX) and exo-7-ethyl-5-methyl-6,8-dfoxabicyclot3.2.1]octane (XX), which are assigned the trivial epithets endo- and exo-brevicomin (61). Males of 2 brevicomis synthesize 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin) (XXI) in their hind guts (62), and this compound, in combination with the brevicomins and host-derived myrcene, constitutes a potent attractant for both sexes of J). brevicomis (63). Frontal in, also produced by females of . frontalis (62T7 is reported to function as a powerful aggregative pheromone when combined with host monoterpenes such as a-pinene (64). J). pseudotsugae... 

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