EFFECT OF PBAN ON PHEROMONE PRODUCTION BY MATED <Emphasis Type="Italic">Heliothis virescens</Emphasis> AND <Emphasis Type="Italic">Heliothis subflexa</Emphasis> FEMALES

Mated female Heliothis virescens and H. subflexa were induced to produce sex pheromone during the photophase by injection of pheromone biosynthesis activating neuropeptide (PBAN). When injected with 1 pmol Hez-PBAN, the total amount of pheromone that could be extracted from glands of mated females during the photophase was similar to that extracted from virgin females in the scotophase. The PBAN-induced profile of pheromone components was compared between mated, PBAN-injected females and virgin females during spring and fall. Virgin females exhibited some differences in the relative composition of the pheromone blend between spring and fall, but no such temporal differences were detected in PBAN-injected, mated females. Because the temporal variation in pheromone blend composition was greater for virgin females than for PBAN-injected females, PBAN can be used to determine a females native pheromone phenotype. This procedure has the advantages that pheromone glands can be extracted during the photophase, from mated females that have already oviposited.     

Pheromone Analysis of Wild Female Moths with a PBAN C-Terminal Peptide Injection for an Estimation of Assortative Mating in Adzuki Bean Borer, Ostrinia scapulalis

The adzuki bean borer, Ostrinia scapulalis, has distinct genetic variation in the blend of two sex pheromone components, (E)- and (Z)-11-tetradecenyl acetates. This variation is largely controlled by a single autosomal locus with two alleles, E and Z. E-type (EE) females produce a pheromone with a mean E:Z ratio at 99:1 whereas Z-type (ZZ) and I-type (ZE) produce pheromones with mean of 3:97 and 64:36, respectively. Interestingly, in many natural populations of O. scapulalis in Japan, this pheromone polymorphism appears to be stably maintained. We tried to predict the changes in relative abundance of each pheromone type by estimating the pheromone production genotype of wild females and their male mates. The pheromone titer in the wild, mated females was increased without changing the blend ratio by an injection of a peptide with pheromone biosynthesis activating activity (TKYFSPRL-NH2). The frequencies of E-, I-, and Z-types at Matsudo were 15, 52, and 33%, respectively, and did not deviate from the Hardy-Weinberg expectations. The estimated mating patterns were concordant with the assumption that no assortative mating was occurring in this population, and this is suggested as a cause of sustained polymorphism at Matsudo.     

Identification and Biosynthetic Studies of the Hydrocarbon Sex Pheromone in <Emphasis Type="Italic">Utetheisa ornatrix</Emphasis>

The type II class of sex pheromones found in moths is composed of polyene hydrocarbons and their epoxides. Analysis of Utetheisa ornatrix females by gas chromatography-mass spectrometry and measurement of responses of male moths by coupled gas chromatography-electroantennogram detection confirmed the presence of large amounts of (Z,Z,Z)-1,3,6,9-heneicosatetraene (1,3,6,9-21:Hy) and smaller amounts of (Z,Z, Z)-3,6,9-heneicosatriene (3,6,9-21:Hy). Both compounds were detected in pheromone glands of newly emerged adults, with low amounts found in the late pupal stage, indicating that sex pheromone biosynthesis started in the late pupal stage. In our population of females (several hundred sampled), approximately 90% produced the tetraene, 1,3,6,9-21:Hy, as the major component, while the other 10% produced only a large amount (1500-2000 ng) of 3,6,9-21:Hy, with no detectable amount of the tetraene. This result could indicate that two distinct populations are present in our original collection site in Florida. Decapitated female moths accumulated 3,6,9-21:Hy and 1,3,6,9-21:Hy compared to the same age normal females, indicating that female moths continuously produce pheromone. A pheromone biosynthesis activating neuropeptide (PBAN)-like neuropeptide did not affect sex pheromone production as indicated by injection of synthetic PBAN and decapitation of U. ornatrix female adults. When the labeled precursor, D4-9,12,15-18:acid, was injected into the early pupal stage, the most abundantly labeled hydrocarbons were 3,6,9-21:Hy and 1,3,6,9-21:Hy in the female adults. This result indicated that 3,6,9-21:Hy could be biosynthesized from linolenic acid through chain elongation and decarboxylation. To determine how 1,3,6,9-21:Hy is produced, D4-3,6,9-21:Hy was injected into pupae and monitored for incorporation of label. No label was incorporated into 1,3,6,9-21:Hy, although a large amount of triene, 3,6,9-21 :Hy, was recovered in the pheromone gland. This indicates that U. ornatrix females do not use 3,6,9-21:Hy to produce 1,3,6,9-21:Hy, and the terminal double bond is introduced earlier in the biosynthetic pathway.     

Effects of sublethal deltamethrin on the chemical communication system and PBAN activity of Asian corn borer,Ostrinia furnacalis (Güenee)

Topically applied sublethal doses of deltamethrin may interrupt chemical communication between the two sexes of the Asian corn borer, Ostrinia furnacalis (Güenee), by affecting the probability of calling behavior, sex pheromone titer and PBAN-like activity. At the 1st, 2nd, and 4th day of posttreatment with deltamethrin (1 ng/moth), female O. furnacalis showed 32, 36, and 46% calling probabilities of control female moths, while the sex pheromone titer of females was only 15, 20, and 25% the amount of control females, respectively. The chemical communication system was significantly affected even at the 4th day post-treatment. By injections of 1, 1/2, 1/4, and 1/8 female equivalent of brain and subesophageol ganglion homogenate of 1 ng deltamethrin-treated females into decapitated females, female pheromone production was reduced to 64, 31, 30.7, and 8.1% of that of control female moths, respectively. This result appears to indicate that sublethal deltamethrin affected the activity of the PBAN-like factor of O. furnacalis.