Weevil Granary, Sitophilus granarius

Sitophilate [1-ethylpropyl (2S,3 )-2-methyl-3-hydroxypentanoate, 24] is the male-produced aggregation pheromone of the granary weevil (Sitophilus granarius). Its racemate is also bioactive. Almeida synthesized ( )-24 by diaster eoselective hydrogenation of the Baylis-Hillman adduct A to B as shown in Scheme 37 [60]. This high diastereoselectivity could be observed only with TBS-protected ester A to give pure B. 

Resistant species, such as southern armyworms, require injected doses up to 800 mg KCN/kg BW (332 mg HCN/kg BW) or diets of 3600 mg KCN/kg for 50% mortality (Brattsten et al. 1983), but data are scarce for other terrestrial invertebrates. Exposure to 8 mg HCN/L air inhibits respiration in the granary weevil (Sitophilus granarius) within 15 min and kills 50% in 4 h some weevils recover after cessation of 4-h exposure (Towill et al. 1978). 

Two propanoate units (see Fig. 2) seem to be coupled in 1-ethylpropyl (2S,3.R)-2-methyl-3-hydroxypropanoate 221, the male produced aggregation pheromone of the granary weevil, Sitophilus granarius [390-393]. Even the ester-moiety may origin from two propanoate units after decarboxylation and reduction Three propanoate units (and decarboxylation, see Fig. 2) may produce (4S,5 )-5-hydroxy-4-methyl-3-heptanone, sitophilure 222, the aggregation pheromone of the rice weevil, Sitophilus oryzae [394, 395]. The same carbon skeleton is present in the achiral 4-methylheptan-3,5-dione 223, the pheromone of the pea weevil, Sitona lineatus [396-398]. 

Exposure under vacuum reduces exposure times for complete kill of the lesser grain borer Rhyzopertha dominica at about 20°C from several weeks to a few days (Jay, 1986 Locatelli and Daolio, 1993), while exposure at raised pressures of 10 and 15 bar achieved complete kill of all stages of the granary weevil Sitophilus granarius (L.) within 16h and 8 h respectively at this temperature (Le Torc h and Fleurat Lessard, 1991). At 20bar and 20°C, control of a variety of stored-product... 

Robinson, W. (1926) Low temperature and moisture as factors in the ecology of the rice weevil, Sitophilus oryzae L. and the granary weevil, Sitophilus granarius L. University of Minnesota Exp. Station Report, 41, 40 pp. 

Russell, G.R. 1988. Evaluation of four analytical methods to detect weevils in wheat Granary weevil, Sitophilus granarius (L.), in soft white wheat. J. Food Protec. 51, 547-553. 

The same enzymes were also applied to the DKR of a-alkyl-P-keto esters, such as 20, 21, 43, and 44, for the preparation of the corresponding hydroxy esters with excellent chemical and optical purity, as shown in Scheme 12.22 [55a,57j. In this case, substrate 43 was selected for the asymmetric chemoenzymatic synthesis of the aggregation pheromone 45 (sitophilate) of the granary weevil Sitophilus granarius (Scheme 12.23) [57]. 

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