Suppression of leopard moth (Lepidoptera: Cossidae) populations in olive trees in Egypt through mating disruption.

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2,13-octadecenyl acetate and (E,Z)-3,13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 +/- 2.9 kg per tree) and 2007 (23 +/- 1.3 kg per tree) compared with control ones (61.0 +/- 3.9 and 10.0 +/- 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.

Insecticidal activity of Citrus aurantium fruit, leaf, and shoot extracts against adult olive fruit flies (Diptera: Tephritidae).

Solvent extracts of differing polarity from Citrus aurantium (L.) (Rutaceae) fruit, leaves, and shoots were evaluated for biological activity against adults of the olive fruit fly, Bactrocera oleae (Gmelin) (Diptera: Tephritidae). Using a petri dish residual exposure bioassay, we found that the petroleum ether extract from fruit alone showed insecticidal activity against the flies. The extract of the three fruit tissues (flavedo [peel], albedo, and flesh) indicated that bioactivity was limited to the flavedo, and this activity was significantly higher than that of the whole fruit extract. The most effective extract was obtained when fresh flavedo was used, whereas extracts of oven-dried flavedo were inactive. Fruit maturity also affected bioactivity; extracts of ripe fruit were more effective than those of unripe fruit. Our results suggest that C. aurantium flavedo contains secondary metabolites with insecticidal activity against B. oleae adults.

Partial purification and insecticidal activity of toxic metabolites secreted by a Mucor hiemalis strain (SMU-21) against adults of Bactrocera oleae and Ceratitis capitata (Diptera: Tephritidae).

The secondary metabolites present in the methanol extract of a Mucor hiemalis strain (SMU-21) mycelia, cultured in liquid medium, were evaluated for toxicity to Bactrocera oleae (Gmelin) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults. Feeding and contact bioassays revealed that the methanol fraction of the crude supernatant was strongly toxic to both species. Symptoms of toxicity developed quickly; lethargy occurred 1-2 h posttreatment, and mortality reached 82-97% after 24 h. Both feeding and contact bioassays showed that B. oleae was more susceptible than C. capitata. Concentrations producing 50% mortality (LC50) to B. oleae and C. capitata after 24 h in feeding bioassays were 0.52 and 1.28 mg/ 0.1 ml diet, respectively, but 34.8 and 64.0 microg/ cm2, respectively, after 4 h in contact bioassays. Solvent partition, precipitation, and chromatographic procedures were used to isolate the active principles from the crude supernatant. These resulted in the isolation of one high-pressure liquid chromatography fraction with insecticidal activity on B. oleae flies equal to the initial crude supernatant.

Microflora species and their volatile compounds affecting development of an alcohol dehydrogenase homozygous strain (Adh-I) of Bactrocera (Dacus) oleae (Diptera: Tephritidae).

Microflora species and volatiles emitted from artificial diets were examined from the larvae of three homozygous alcohol dehydrogenase (Adh) strains of the olive fruit fly, Bactrocera (Dacus) oleae (Gmelin), reared under identical conditions. Differences in volatile composition were detected when Adh-I homozygous larvae developed in a diet lacking the preservative p-hydroxybenzoic acid methyl ester (nipagin). Larval development of the Adh-I strain in the preservative-free diet was reduced by 50%, whereas pupal emergence was completely inhibited. The larval development and pupal emergence of Adh-F and Adh-S strains were not affected. Unique microorganisms with characteristic volatile profiles were isolated from the preservative-free diet of the Adh-I strain that were different from those, isolated from Adh-S, Adh-F, laboratory colony, and wild insect populations. Our results indicated that the variations in volatile composition of the artificial diets, and the inhibition of larval development and pupal emergence in Adh-I strain were related to changes in the microflora that developed in the diets of the Adh-I strain.

Chemical composition of corn leaf essential oils and their role in the oviposition behavior of Sesamia nonagrioides females.

The chemical composition of the volatile oils collected by steam distillation from leaves of seven corn hybrids and their effect on the oviposition behavior of Sesamia nonagrioides females was studied. Samples of the volatile oils from each of the hybrids were analyzed by capillary gas chromatography-mass spectrometry (GC-MS) and several major compounds were identified. The major compound found in all seven hybrids was 3,7,11,15-tetramethyl-2-hexadecen-1-ol (phytol), ranging from 38.3 to 64.9% of the total quantity. Compounds detected in significant proportions include (Z)-3-hexenol (3.1 to 8%), nonanal (4.9 to 14.5%), pentadecanal (1.8 to 5.8%), neophytadiene (5.5 to 12.9%), (Z)-3-hexenyl acetate (2.5 to 8.9%), and an analogue of 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3-(4H)-one (DIMBOA) (2.4 to 9.3%). The analysis showed no qualitative differences among the chemicals identified while quantitative differences were detected. Among the volatile oils, the significant difference was in the quantity of aldehydes present. In two-choice bioassays, filter paper sticks treated with volatile oils containing higher quantity of aldehydes received fewer eggs than those with lower aldehyde quantity. Bioassays with synthetic aldehydes of a chain length C9-C14 confirmed the above results.

Alkadienes and alkenes, sex pheromone components of the almond seed wasp Eurytoma amygdali.

Whole body extracts of virgin Eurytoma amygdali females were attractive to males in laboratory bioassays. Extracts of various body parts of the female wasp elicited different responses to males, with the thorax extract being the most active. Preparative fractionation of the crude hydrocarbon extract on a silver nitrate impregnated silica gel column (alkanes, alkenes, and alkadienes) revealed that the highest male response was elicited by alkadienes and the lowest by alkenes, with the alkane fraction being inactive. The identification of alkenes and alkadienes was based on gas chromatographic, mass spectrometric, and gas-phase infrared data. Laboratory bioassays suggested that the two alkadienes, (Z,Z)-6,9-tricosadiene [(Z,Z)-6,9-C23:2], and (Z,Z)-6,9-pentacosadiene [(Z,Z)-6,9-C25:2], and to a lesser extent alkenes, identified in the female extract of E. amygdali were male attractants.