A. De Cristofaro

Chemical Ecology and Management of Lobesia botrana (Lepidoptera: Tortricidae)

ABSTRACT The moth Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) feeds on grapes (Vitis vinifera L.), reducing yield and increasing susceptibility to fungal infections. L. botrana is among the most economically important insects in Europe and has recently been found in vineyards in Chile, Argentina, and California. Here, we review L. botrana biology and behavior in relation to its larval host (the grapevine) and its natural enemies. We also discuss current and future control strategies in light of our knowledge of chemical ecology, with an emphasis on the use of the sex pheromone-based strategies as an environmentally safe management approach. Pheromone-mediated mating disruption is the most promising technique available on grapes and is currently implemented on ≈140,000 ha in Europe. Experience from several growing areas confirms the importance of collaboration between research, extension, growers, and pheromone-supply companies for the successful implementation of the mating disruption technique. In the vineyards where mating disruption has been successfully applied as an areawide strategy, the reduction in insecticide use has improved the quality of life for growers, consumers, as well as the public living near wine-growing areas and has thereby reduced the conflict between agricultural and urban communities.

Electrophysiological and Behavioral Activity of (E)-2-Hexenal in the Granary Weevil and Its Application in Food Packaging

The purpose of this work was to develop a biodegradable carrier material to control insect pests in cereal products. To this aim, (E)-2-hexenal was used, being a natural compound with antimicrobial activity that is also commonly adopted as a flavoring agent. Three coating layers of polycaprolactone (PCL) were spread onto the internal side of a paperboard carton, the first being the active coating containing (E)-2-hexenal. The antennal sensitivity of Sitophilus granarius to a broad range of doses of (E)-2-hexenal was first demonstrated. Next, the ability of different concentrations of this compound to disrupt the orientation of adult S. granarius beetles to odors of intact wheat kernels was established in a two-choice pitfall bioassay. In addition, invasion tests were carried out over an 8-week period to highlight the effects of the biobased repellent packaging and their potential persistence. The results demonstrated that during the entire monitoring period, the percentage of S. granarius adults found in cartons coated with (E)-2-hexenal-loaded multilayer PCL was about 10 % of the total number of insects used in the bioassay, very low compared with the respective control samples, thus assessing both the effectiveness and persistence of the repellent system developed. Although the infestation level of treated packages was reduced relative to the infestation levels in the controls, any infestation of food packages is unacceptable to consumers, so further tests are required to determine whether infestation can be completely prevented using (E)-2-hexenal.

Electrophysiological and Behavioral Responses of Oriental Fruit Moth to the Monoterpenoid Citral Alone and in Combination with Sex Pheromone

ABSTRACT The monoterpenoid citral synergized the electroantennogram (EAG) response of male Grapholita molesta (Busck) antennae to its main pheromone compound Z8–12:OAc. The response to a 10-µg pheromone stimulus increased by 32, 45, 54, 71 and 94% with the addition of 0.1, 1, 10, 100 and 1,000 µg of citral, respectively. There was no detectable response to 0.1, 1, or 10 µg of citral; the response to 100 and 1,000 µg of citral was 31 and 79% of the response to 10 µg of Z8–12:OAc. In a flight tunnel, citral affected the mate-seeking behavior of males. There was a 66% reduction in the number of males orientating by flight to a virgin calling female when citral was emitted at 1,000 ng/min ≈1 cm downwind from a female. Pheromone and citral induced sensory adaptation in male antennae, but citral did not synergize the effect of pheromone. The exposure of antennae to 1 ng Z8–12:OAc/m3 air, 1 ng citral/m3 air, 1 ng Z8–12:OAc + 1 ng citral/m3 air, or to 1 ng Z8–12:OAc + 100 ng citral/m3 air for 15 min resulted in a similar reduction in EAG response of 47–63%. The exposure of males to these same treatments for 15 min had no effect on their ability to orientate to a virgin calling female in a flight tunnel. The potential for using citral to control G. molesta by mating disruption is discussed.

Sensory Adaptation of Antennae and Sex Pheromone-Mediated Flight Behavior in Male Oriental Fruit Moths (Leptidoptera: Tortricidae) After Prolonged Exposure to Single and Tertiary Blends of Synthetic Sex Pheromone

ABSTRACT Sensory adaptation has been measured in the antennae of male Grapholita molesta (Busck) after 15 min of exposure to its main pheromone compound (Z)-8-dodecen-1-yl acetate (Z8-12:OAc) at the aerial concentration of 1 ng/m3 measured in orchards treated with pheromone for mating disruption. Exposing males to this aerial concentration of Z8-12:OAc for 15 min, however, had only a small effect on their ability to orientate by flight to virgin calling females in a flight tunnel. Experiments were undertaken to determine if exposure to the main pheromone compound in combination with the two biologically active minor compounds of this species, (E)-8-dodecen-1-yl acetate (E8-12:OAc) and (Z)-8-dodecen-1-ol (Z8-12:OH) would induce greater levels of sensory adaptation and have a greater effect on male sexual behavior. The exposure of male antennae to 0.5 g/m3 air of one of the three pheromone compounds induced sensory adaptation to this compound and to the other two pheromone compounds demonstrating cross adaptation. Average percentage sensory adaptation to a pheromone compound was similar after 15 min of exposure to 1 ng/m3 air of Z8-12:OAc, or to 1 ng/m3 air of a 1:1:1 or 93:6:1 blend of Z8-12:OAc, E8-12:OAc, and Z8-12:OH. The exposure of males to 1 ng/m3 air of Z8-12:OAc or the two ratios of Z8-12:OAc, E8-12:OAc, and Z8-12:OH for 15 min had no effect on their ability to orientate to a virgin calling female. The implications of these results for the operative mechanisms of sex pheromone-mediated mating disruption of this species are discussed.