Pheromones field bioassay

The pheromone chemistry of A. hilare has been studied in detail, using both laboratory (vertical Y-tube) and field bioassays [75]. In Y-tube bioassays, mature females were attracted by male odors, but males were not attractive to other males, and females were not attractive to either sex. Males produced (-)-cis-Z-BAE and (-)-frazzs-Z-BAE in a -19 1 ratio, and other compounds in the extracts were not active. The 19 1 blend was more attractive to females than other ratios, and the individual components were not attractive, indicating that both compounds were required. Females were attracted to the synthetic blend in field cage trials [75],but as with most other phytophagous pentatomids,few bugs were caught in pheromone-baited traps (J.G. Millar and H.M. McBrien, unpublished data). 

Almost simultaneously with the identification of 2E, 4 , 6Z- 10 COOMe, a thermally unstable stereoisomer, 2E, 4Z, 6Z- 10 COOMe 118, was found to be a key component of the male-produced sex pheromone of Thyanta pallidovirens> along with the sesquiterpenes (+)-a-curcumene, (-)-P-sesquiphellandrene, and (-)-zingiberene 119 [10,25]. 2E, 4Z, 6Z-10 COOMe was an essential component of the attractive blend, whereas any one, any two, or all three of the sesquiterpene components were equally effective as the other portion of the blend. None of the components were active alone. Pheromone blends attracted only females in both laboratory and field bioassays [10]. The same compounds are also produced by the congener T. custator [10] and other Thyanta spp. (J.G. Millar, unpublished data). 

The synthesis of pheromones remains an important cornerstone of pheromone research and development. The initial synthesis of an insect pheromone serves not only to confirm the structural identification, but also provides authentic material for either laboratory or field bioassay. Oftentimes, larger quantities of the pheromones are desired for the development of monitoring and pest control methods. The scale up of the synthesis of complex pheromone compounds is often a major bottleneck in the practical application of pheromones. Also, the unusual structure of some pheromone compounds beckons synthetic chemists to apply new methodology in order to show off their methods. 

Field bioassays with adult cerambycid beedes, Neoclytus acuminatus acumi-natus (F.) (Coleoptera Cerambycidae), revealed that males produce a pheromone that attracts both sexes. Male extracts revealed a single major male-specific compound IS, 3>S )-hexanediol. Field trials showed that a racemic blend of IS, 3S) and 2R, 3i )-hexanediols attracted both sexes and that activity was similar to enantiomerically enriched IS, 3S) hexanediol (e.e. 80.2%). However, a blend of all four stereoisomers attracted only a few beetles. ... 

The first technique using pheromones to manipulate the southern pine beetle population relies on inhibition. Field bioassays have shown that aggregation of the southern pine beetle on attractant-baited traps can be significantly reduced by the... 

Smith, R.G. (1976). Laboratory and field bioassay of the Douglas-fir tussock moth pheromone, (Z)-6-heneicosen-ll-one. Environ. Entomol., 5,1187-1190. 

It has been discovered that the crucifer flea beetle, Phyllotreta cruciferae Goeze, a significant pest of oilseed Brassica and other cruciferous crops in North America and Europe, uses a hydrocarbon pheromone. The first published evidence for a pheromone in P. cruciferae was that canola plants infested by unsexed adults were more attractive to both males and females than damaged plants only, in both laboratory and field bioassays (Peng and Weiss, 1992). Subsequently, Peng et al. (1999) determined with field bioassays that the males were the attractive sex, fitting the pattern of a male-produced aggregation pheromone. 

Zilkowski, B. W., Bartelt, R.J., Cosse, A.A. and Petroski, R.J. (2006). Male-produced aggregation pheromone compounds from the eggplant flea beetle (Epitrix fuscula) identification, synthesis, and field bioassays. J. Chem. Ecol., 32, 2543-2558. 

The San Jose scale, Quadraspidiotus perniciosus, is a serious worldwide pest of deciduous fruit trees. The pheromone has been shown to be a three-component mixture of 7-methyl-3-methylene-7-octen-l-yl propanoate (XIX), (Z)-3,7-dimethyl-2,7-octadien-l-yl propanoate (XX), and the corresponding (15)-isomer XXI (55, 56, 57) (Figure 8). Greenhouse and field bioassays have shown that XIX, XX, and XXI are independently attractive to the male San Jose scale and that the three components show almost equal attractancy (55,57). Interestingly, neryl and geranyl propanoate are inactive. 

Table IV. Field Bioassay of Synthetic Pheromone 6 in Conjunction with Food Volatiles...

Field bioassay with authentic synthetic material confirmed that a 9 1 mixture of acetate and aldehyde was highly attractive and thus constituted the sex pheromone. 

Table 18.1 Known and possible female-produced sex pheromone components for arctiid moths. Compounds in bold have been found in pheromone gland extracts or aeration extracts and have been shown to be active in behavioral bioassays or field trials compounds in normal font have been found in pheromone gland or aeration extracts and compounds in italics have been shown to attract males infield screening trials.

Pheromone Bioassay Field test location Other issues Reference... 

Bioassay wt = wind tunnel, f = field traps. Other issues chem = pheromone chemistry, mult = multi-species lures, cr = cross attraction, seas = seasonal patterns, tp = trapping parameters such as height, type, pheromone dose, pheromone formulation/aging, or host-related synergist, wh = warehouse environment. 

However, whereas the silkworm female appears to attract males with a single sex pheromone, many other insects use blends of pheromones as chemical releasers of behavior. This phenomenon is strikingly illustrated in the case of males of the bark beetle Ips paraconfusus (=Ips confusus) which utilize three monoterpene alcohols as an aggregation pheromone (11). Maximum attraction of beetles in the field was exhibited in the presence of a mixture of all three compounds, whereas single or pairs of compounds were considerably less active (12). Similarly, in laboratory bioassays, mixtures of compounds were vastly superior to single constituents as attractants (13). 

The bioassay of (l/ ,55,7R)-(+)-exo-brevicomin (76) and its (-)-enantiomer 16 ) was carried out by Professor David L. Wood and coworkers at the University of California, Berkeley. When I visited his laboratory in June 1974, I was deeply impressed by the fact that only (+)-76 was pheromonally active to attract the beetles. A large-scale field test also indicated that (+)-76 was the bioactive isomer, while (—)-76 was neither active nor inhibitory.32 Thus, only a single enantiomer of the pheromone was found to... 

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