Kairomones ofheliothis armigera andcorcyra cephalonica and their influence on the parasitic potential oftrichogramma chilonis (Trichogrammatidae: hymenoptera)

Kairomones from moth scales tend to influence the parasitic potential byTrichogramma chilonis Ishii. Hexatriacontane, pentacosane, heptadecane, docosane and 2, 6, l0-dodecatrienal-3, 7, 11-trimethyl were identified from the active moth scale extract ofHeliothis armigera Hubner (its natural host) andCorcyra cephalonica Stainton (a laboratory host). The significance of an array of compounds from moth scales with kairomonal activity for manipulating entomophagous insects in biological control programmes is discussed.     

Insecticidal activity of Origanum majorana L. essential oil as anti‐cholinergic agent

The present study was focused on exploring the presence of active compounds in Origanum majorana essential oil (OmEO), and its various knock‐down effects against the rice moth, Corcyra cephalonica. GC–MS analysis detected the existence of major compounds such as monoterpenes, cis‐β‐terpineol and terpinen‐4‐ol with the total proportion of 52.16%. Fumigant toxicity against adult and larvae was calculated with an LC₅₀ value of 11.31 and 49.83 μL/L air, respectively. The contact toxicity against adult, pupa, larvae and eggs was observed with LC₅₀ value 2.54, 0.95, 2.78, and 0.49 μL/L, respectively. Furthermore, the influential repellent behavior against adults has been observed. Acetylesterase (AChE) inhibition activity of OmEO was observed against adult and larvae of C. cephalonica with an IC₅₀ value of 35.89 and 118.54 μL/mL, respectively. Moreover, computational docking study revealed the binding affinity of Cis‐β‐terpineol and terpinen‐4‐ol towards the active binding sites of AChE. On the other hand, Fluorescence‐assisted cytometry and comet assay confirmed the cytotoxic and genotoxic effect of OmEO at various concentrations on C. cephalonica. Altogether, the results showed the knock‐down effect of OmEO against C. cephalonica, and it could be a potential biocontrol measure against the stored product pest.     

Significance of the 19-kDa hemolymph protein HP19 for the development of the rice moth Corcyra cephalonica: morphological and biochemical effects caused by antibody application

The hemolymph protein HP19 of the rice moth, Corcyra cephalonica, mediates the 20-hydroxyecdysone (20E)-dependent acid phosphatase (ACP) activity at a nongenomic level. Affinity-purified polyclonal antibody against HP19 (alphaHP19-IgG) was used in the present study to understand the role of HP19 during the postembryonic development of Corcyra. In the in vitro studies, HP19 action was blocked either by immuno-precipitation using alphaHP19-IgG, prior to its addition to the fat body culture or by the addition of the antibody directly to the culture, along with 20E and hemolymph containing HP19. The alphaHP19-IgG blocked the HP19-mediated 20E-dependent ACP activation. In the in vivo studies, the alphaHP19-IgG was injected into the fully developed last (final/Vth) instar larvae of Corcyra, to complex the HP19 in vivo, in order to block the action of HP19. The injection of alphaHP19-IgG resulted in defective development of larvae, which grew either into non-viable larvae or larval-pupal/pupal-adult intermediates relative to the effect of pre-immune IgG injected controls. The present study shows that HP19 plays an important role in controlling the metamorphosis of Corcyra by regulating the 20E-dependent ACP activity. Coupled with the earlier findings, the ecdysteroid hormone regulates this action at a nongenomic level.     

Field dispersal of the parasitoid wasp Habrobracon hebetor (Hymenoptera: Braconidae) following augmentative release against the millet head miner Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

Pearl millet is one of the major staple food crops in Sub-Sahelian Africa, and the millet head miner (MHM) [Heliocheilus albipunctella] is its major pest, causing serious economic damage in the maturity period. We studied the dispersion patterns of the endogenous ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), after augmentative releases in pearl millet fields for biological control of the MHM, in 2010 and 2011 in Burkina Faso and Niger. The parasitoids were released using 15 jute bags per release site. Parasitoid dispersion was indirectly monitored through weekly assessments of MHM parasitism by H. hebetor at different distances from release points (0, 3 and 5?km) and in control villages (15?km). Our findings indicate that the jute bags released approximately 900–1000 parasitoids per site over a period of three weeks. This initial parasitoid population led to higher parasitism of MHM larvae at the site of dissemination compared to farms at distances of 3 and 5?km. However, usually after five weeks, successive generations of H. hebetor dispersed up to 3?km, causing high levels of MHM larval mortality, which sometimes is similar to those of the release points. Based on these results, we recommend the release of parasitoids at sites spaced 3?km for timely and more efficient control of MHM populations.     

Space allocation in Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger) (Col., Buprestidae) in the attack of Greek fir [Abies cephalonica Loud. var. graeca (Fraas) Liu]: a pattern to process approach

The phloeo‐cambiophagous buprestid Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger.) is not a primary factor of fir decline problem although the beetle substantially contributes to Greek fir Abies cephalonica Loud. var. graeca (Fraas) Liu mortality. By using mapping depiction of the exit holes of the insect on a set of fir trees located on a line transect in a randomized point‐centred quarter scheme and employing pattern analysis techniques we were able to reveal various scales of the infestation pattern. Four scales were recognized, two of them corresponding to the pattern of microsite selection on the bark of a fir tree. While the dispersed exit holes exhibited a statistically significant random dispersion on the bark, within each aggregation the pattern was uniform. The area of compartments created by Dirichlet partition approximated very well the sizes of the actual larval galleries. The Dirichlet tessellation of the bark space and the analysis of the parameter of the resulting partitions showed the predominance of the hexagonal conformation of the larval spaces when space was limited. When some exit holes were positioned close together it was found that they were directed away from each other so the resulting galleries were well separated. Several hypotheses are presented as to the mechanisms underpinning the observed patterns. The allocation of space is in accordance with the widely accepted ‘central place theory’ of W. Christaller, a general theory of pattern generated in the geographical dispersion of human settlements. The revealed pattern was also in accordance with the predictions of the theory of ‘central place foraging’ of R. H. MacArthur and the theory of ‘resource concentration hypothesis’ of R. Root.     

ANALYSIS OF THE Vitellogenin GENE OF RICE MOTH,Corcyra cephalonica STAINTON

Vitellogenin (Vg) is a precursor of the major yolk protein, an essential nutrient for the embryonic development of oviparous animals including insects. Here, the gene(CceVg [Corcyra cephalonica Vg] ) encoding the Vg (CceVg of moth, C. cephalonica, was cloned and sequenced. The gene sequence was 6,721‐bp long and contained 5five introns and six exons that together formed a 5,382‐bp open reading frame. The deduced protein (CceVg) consisted of 1,793 amino acid residues, including a 16‐amino‐acid signal peptide. The putative molecular weight of the primary Vg protein was 202.46 kDa. The CceVg contained all conserved domains and motifs that were commonly found in most insect Vgs except the presence of a polyserine tract at the C‐terminal region, which had not been reported in other lepidopteran Vgs. The expression pattern showed thatCceVg was first transcribed at a very low level in the early larval stage but disappeared in later stage larva. In female, theCceVg mRNA was detected in early pupal stage and throughout adult stage. Interestingly, theCceVg mRNA was detected only in mated males at low levels, not in the virgin ones. Injection ofCceVg double‐stranded RNA into early‐emergent females caused severely abnormal ovaries.     

艾叶精油对玉米螟赤眼蜂的影响及两者对米蛾的联合作用

玉米螟赤眼蜂是生物防治中一种重要的天敌昆虫,为探明艾叶精油对玉米螟赤眼蜂的影响及两者对米蛾的联合防治效果,本文研究了艾叶精油熏蒸、触杀、驱避活性对玉米螟赤眼蜂的影响及艾叶精油和玉米螟赤眼蜂对米蛾的联合作用。结果表明,艾叶精油熏蒸和触杀处理对玉米螟赤眼蜂卵具有明显影响,寄生在米蛾卵上的玉米螟赤眼蜂卵经0.1、0.2、0.3、0.4、0.5、0.6μg/cm3艾叶精油熏蒸处理72h后玉米螟赤眼蜂的羽化率分别为56.67%、49.33%、44.00%、33.33%、26.00%和14.67%;寄生在米蛾卵上的玉米螟赤眼蜂卵经100、200、300、400、500、600mg/L艾叶精油触杀处理72h后玉米螟赤眼蜂的羽化率分别为54.00%、45.33%、38.00%、28.67%、18.00%和6.00%,均与对照组表现出显著性差异。艾叶精油驱避活性对玉米螟赤眼蜂成蜂也有明显的影响,300mg/L艾叶精油对玉米螟赤眼蜂的驱避率79.05%,随着时间间隔和距离间隔的增加,这种影响作用降低;联合应用艾叶精油与玉米螟赤眼蜂时先释放玉米螟赤眼蜂,24h后再滴加艾叶精油的防治效果最佳,米蛾的死亡率可高达96%。     

米蛾对三种赤眼蜂的适合性及被寄生后卵内游离氨基酸含量的变化

寄生发生前寄生蜂的寄生行为及寄生发生后寄生蜂的生长发育情况能够反映出寄主对寄生蜂的适合性,而寄生蜂对寄主营养物质的吸收和利用是寄生蜂完成发育的生理基础。为了从寄生蜂利用寄主营养能力的角度探讨寄主对不同种赤眼蜂适合性变化的原因,本文观察了以米蛾Corcyra cephalonica Stainton卵为寄主时拟澳洲赤眼蜂Trichogramma confusumViggiani、松毛虫赤眼蜂T. dendrolimi Matsumura和玉米螟赤眼蜂T. ostriniae Pang et Chen的寄生行为及发育和存活情况,测定了被寄生米蛾卵内游离氨基酸的含量 。结果发现,玉米螟赤眼蜂的产卵时间为84.9 s,显著长于拟澳洲赤眼蜂和松毛虫赤眼蜂的产卵时间。拟澳洲赤眼蜂检测寄主所需时间为30.8 s,显著长于玉米螟赤眼蜂和松毛虫赤眼蜂所需时间,但从每寄主卵中羽化出的拟澳洲赤眼蜂数量显著高于松毛虫赤眼蜂及玉米螟赤眼蜂寄生的结果。3种赤眼蜂卵+幼虫的发育历期间不存在显著差异,但卵成虫的发育历期间存在显著差异。玉米螟赤眼蜂幼虫期和预蛹期的死亡率均显著高于拟澳洲赤眼蜂和松毛虫赤眼蜂相应虫期的死亡率。这些结果表明：米蛾卵对松毛虫赤眼蜂及拟澳洲赤眼蜂的适合性高于对玉米螟赤眼蜂的适合性。未被寄生的米蛾卵内游离氨基酸的总量在24～96 h时间段内从开始的2.194 mg/mL逐渐下降到1.565 mg/mL,而被寄生的米蛾卵内游离氨基酸总量均出现先升高后下降的现象。被松毛虫赤眼蜂和拟澳洲赤眼蜂寄生的米蛾卵内游离氨基酸总量在48 h达到最高值,分别为4.239 mg/mL和3.222 mg/mL,被玉米螟赤眼蜂寄生的米蛾在72 h达到最高值,为4 .323 mg/mL,显示同玉米螟赤眼蜂相比,松毛虫赤眼蜂和拟澳洲赤眼蜂能够更快地分解利用寄主营养。这些结果提示,3种赤眼蜂利用米蛾卵内营养物质能力的不同导致了米蛾卵对3种蜂适合性的不同。     

Effect of fertilized,unfertilized, and UV‐irradiated hosts on parasitism and suitability for Trichogramma parasitoids

Trichogramma spp. (Hymenoptera: Trichogrammatidae) parasitoids have been commonly used as biological control agents in insect pest management. Host quality is believed to influence parasitism, host preference, and suitability for parasitoids. To date, limited studies have compared the parasitism of Trichogramma parasitoids on fertilized, unfertilized, and sterilized host eggs. Hence, we studied the performance of three Trichogramma egg parasitoids, Trichogramma japonicum Ashmead, Trichogramma chilonis Ishii, and Trichogramma leucaniae Pang & Chen, on fertilized, unfertilized, and ultraviolet (UV)‐irradiated fertilized (UVF) eggs of rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). In a no‐choice test, T. japonicum and T. leucaniae parasitized significantly more fertilized or UVF than unfertilized hosts, and T. chilonis parasitized significantly more UVF than either fertilized or unfertilized hosts. In a choice test, all three Trichogramma parasitoids parasitized UVF hosts the most, and unfertilized hosts the least. There were similar percentages of adult emergence and female progeny among fertilized, unfertilized, and UVF hosts for all three Trichogramma parasitoids, except that T. japonicum had significantly lower adult emergence on fertilized hosts. We also found that all three Trichogramma parasitoids developed slower on unfertilized hosts. Regardless of host treatments, T. leucaniae had the longest developmental time and T. chilonis had the shortest. We conclude that Trichogramma parasitoids prefer parasitizing UVF eggs of C. cephalonica without negative effects on their emergence and sex allocation.     

Natural hybridization in eastern-Mediterranean firs: The case of Abies borisii-regis

The genus Abies is represented in southern Balkans by A. alba, A. cephalonica, and A. borisii-regis. To infer the status of southern-Balkans firs, as well as the extent and patterns of introgression within this taxonomical complex, we analyzed genetic variation patterns of 29 indigenous fir populations in Bulgaria, Macedonia, Greece, and Calabria using a combination of maternally and biparentally inherited markers. Three mitochondrial lineages were observed, one comprising Calabrian populations and two distributed in the Balkans, coinciding with A. alba and A. cephalonica. The boundary between lineages is sharp; only two populations containing a mixture of haplotypes were found. Bayesian analysis of population structure based on seven nuclear microsatellite (nSSR) loci revealed the existence of two clusters whose proportions exhibited a latitudinal cline with a width of 2.3° ( ≈ 255 km). Populations in the center of the latitudinal cline exhibit the most symmetrical, the flattest, and the broadest distributions of cluster proportions within individual tree genomes. A neighbor-net network reflects the cline resulting from the Bayesian analysis. The observed variation patterns are not consistent with the hypothesis of A. borisii-regis as a monophyletic taxon or a stabilized hybridogenous species resulted from ancient hybridization; the taxon rather is a product of recent introgression.