Clustering of loci controlling species differences in male chemical bouquets of sympatric Heliconius butterflies

The degree to which loci promoting reproductive isolation cluster in the genome – i.e. the genetic architecture of reproductive isolation - can influence the tempo and mode of speciation. Tight linkage between these loci can facilitate speciation in the face of gene flow. Pheromones play a role in reproductive isolation in many Lepidoptera species, and the role of endogenously-produced compounds as secondary metabolites decreases the likelihood of pleiotropy associated with many barrier loci. Heliconius butterflies use male sex pheromones to both court females (aphrodisiac wing pheromones) and ward off male courtship (male-transferred anti-aphrodisiac genital pheromones), and it is likely that these compounds play a role in reproductive isolation between Heliconius species. Using a set of backcross hybrids between H. melpomene and H. cydno, we investigated the genetic architecture of putative male pheromone compound production. We found a set of 40 significant quantitative trait loci (QTL) representing 33 potential pheromone compounds. QTL clustered significantly on two chromosomes, chromosome 8 for genital compounds and chromosome 20 for wing compounds, and chromosome 20 was enriched for potential pheromone biosynthesis genes. There was minimal overlap between pheromone QTL and known QTL for mate choice and color pattern. Nonetheless, we did detect linkage between a QTL for wing androconial area and optix, a color pattern locus known to play a role in reproductive isolation in these species. This tight clustering of putative pheromone loci might contribute to coincident reproductive isolating barriers, facilitating speciation despite ongoing gene flow.

The application of sex attractant traps for studying the Zygaenidae (Lepidoptera) fauna of Albania

In Albania, the Zygaenidae family comprises a relatively rich fauna in the Balkans. They have been studied so far using specimens collected only by using entomological nets or by hand-picking. Two groups of sticky Delta traps baited with: 1) a synthetic sex pheromone compound of the Asian species Illiberis rotundata Jordan, 1907 and its opposite enantiomer, alone and in a mixture, and 2) known sex attractants and experimental lures of the genus Zygaena were used in the field in seven localities in southern Albania in 2017 for studying the Procridinae and Zygaeninae fauna, respectively. Four species belonging to the genera Zygaena, Adscita and Jordanita were captured and identified: Zygaena (Zygaena) filipendulae (Linnaeus, 1758), Zygaena (Agrumenia) carniolica (Scopoli, 1763), Adscita (Tarmannita) mannii (Lederer, 1853) and Jordanita (Tremewania ) notata (Zeller, 1847). A. mannii and J. notata were newly recorded in the Counties of Korçë and Gjirokastër. Z. filipendulae was recorded for the first time in the Gjirokastër County and in the municipalities of Prrenjas (Elbasan County) and Finiq (Vlorë County), while Z. carniolica was newly recorded in Prrenjas municipality. Some other sex attractants did not work for either the target species or for other related ones, which we discuss in relation to species cross attraction and geographical variation.

Electroantennogram responses from olfactory receptors in Dαcus oleαe

Substances found in Dacus oleae (Gmelin) (Diptera: Tephritidae) male or female flies which have been reported as pheromones, i.e. elicit some form of biological activity in laboratory or field bioassays, were tested with the electroantennogram technique (EAG). Substances of non-insect origin were also tested as possible pheromone candi­dates. All substances of insect or non-insect origin elicited an EAG response to both sexes of lab-cultured or wild insects but 1,7 dioxaspiro [5,5] undecane, the major pheromone component, has a lower response threshold value than all other compounds. At the maximum stimulus concentration the response to nonanal reaches a value higher than that elicited by all other compounds. EAG responses to various compounds, after receptor adaptation to the major pheromone compound and nonanal, showed that these two compounds are detected by different sets of receptors. Other comments on the sensitivity and specificity of antennal receptors are also presented.

Screening for host plant resistance to Helicoverpa armigera(Hubner) in chickpea using novel techniques

Insights of antibiosis resistance in various chickpea cultivars against pod borer Helicoverpa armigera (Hubner) under laboratory condtions. The present study was carried out in order to investigate the level of resistance against H. armigera on different cultivars by adopting detach leaf and pod assay. In leaf detach assay, pooled mean of 2012 and 2013, significantly lower and maximum weight gain and percent gain recorded was 101.9 mg (88.5%); 382.3mg (317.4%), respectively for ICCV 097105 and ICCV 07306. During podding stage, lowest pod damage (%) was recorded 55 % (ICCV 92944) and highest pod damage recorded by ICC 3137, LL 550 and ICCV07306 (95 %).Highest pupal weight of one day old pupae was recorded on LL 550 (405.2 mg) and lower pupal weight in ICCV 097105 (202.4 mg). The present result gave clue for future in depth studies on weeds for developing either specific pheromone compound or repellant compound for the eco- friendly management of H. armigera.

Effect of certain monounsaturated dodecene and tetradecene acetates and alcohols on electroantennogram response and pheromone-mediated trap catch of the obliquebanded leafroller

The effect of certain monounsaturated dodecene and tetradecene acetates and alcohols on electroantennogram (EAG) response and pheromone-mediated trap catch was examined in male obliquebanded leafroller moths, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). The stimulation of antennae with 0.1 ng of (Z)-11-tetradecenyl acetate (Z11-14:Ac), the major pheromone compound of this species, elicited an EAG response. The use of 1 ng of (Z)-9-tetradecenyl acetate (Z9-14:Ac) or (E)-9-tetradecenyl acetate (E9-14:Ac) or 10 ng of (Z)-9-dodecenyl acetate (Z9-12:Ac) or (E)-9-dodecenyl acetate (E9-12:Ac) was required to elicit a response. One hundred nanograms of (E)-9-tetradecenol (E9-14:OH) were required to elicit a response from antennae. The stimulation of antennae with up to 100 ng of (Z)-9-tetradecenol (Z9-14:OH) did not elicit a response. The addition of 0.1 mg of Z9-12:Ac to 1 mg of synthetic C. rosaceana pheromone consisting of a 100:2:1.5:1 blend of Z11-14:Ac, (E)-11-tetradecenyl acetate, (Z)-11-tetradecenol, and (Z)-11-tetradecenal reduced the capture of moths in pheromone-baited traps by more than 72%. Trap catch was reduced by more than 90% by the addition of 0.01 mg of Z9-14:Ac or E9-14:Ac to 1 mg of C. rosaceana pheromone. There was no detectable reduction in trap catch when 1 mg of E9-12:Ac, Z9-14:OH, or E9-14:OH was added to 1 mg of C. rosaceana pheromone. There was a greater than 95% reduction in trap catch when sources of Z9- or E9-12:Ac were mounted at the entrances to traps, 10 cm from the pheromone source. Trap catch was not affected by placing sources of Z9- or E9-14:Ac at trap entrances. Four 1 or 10 mg sources of E9-14:Ac placed 1 m from a trap did not affect the number of male C. rosaceana captured. The study demonstrates that although a compound may have profound attraction inhibiting activity when mixed directly with C. rosaceana pheromone, this activity may be lost if the inhibitor is emitted a short distance from the pheromone. The study also demonstrates that a potent attraction inhibitor such as E9-14:Ac does not repel C. rosaceana males and must be present along with pheromone to affect the behavior of this species.