Long Chain Alcohols Produced by Trichoderma citrinoviride Have Phagodeterrent Activity Against the Bird Cherry-Oat Aphid Rhopalosiphum padi

In this study we report the effects of fungal metabolites isolated from cultures of the fungus Trichoderma citrinoviride ITEM 4484 on the feeding preference of the aphid Rhopalosiphum padi, a major pest of cereal crops. Different phagodeterrent metabolites were purified by a combination of direct and reverse phase column chromatography and thin-layer chromatography. Chemical investigations, by spectroscopic and chemical methods, led to the identification of different long chain primary alcohols (LCOHs) of the general formula R-OH, wherein R is a long, unbranched, unsubstituted, linear aliphatic group. LCOHs have been reported as components of lepidopteran pheromone blends, but their phagodeterrent effect to aphids is herein reported for the first time. We studied the effects of LCOHs on R. padi by behavioral and electrophysiological bioassays. Feeding preference tests that were carried out with winged and wingless morphs of R. padi showed that LCOHs have a distinctly high phagodeterrent activity and significantly restrain aphids from settling on treated leaves already at a concentration as low as 0.15 mM (0.036 g/l). The results of different electrophysiological analyses indicate that taste receptor neurons located on the aphid tarsomeres are involved in the LCOHs perception. Behavioral assays carried out with some commercial agrochemicals, including azadirachtin A, pyrethrum and mineral oil based products, in combination with 1-hexadecanol, the LCOH most abundantly produced by T. citrinoviride ITEM 4484, showed that these different active principles can be applied together, resulting in a significant additive phagodeterrent effect. Therefore these compounds can be profitably utilized for novel applications in biotechnical control of aphid pests. The LCOHs tested have no chiral centers and therefore can be obtained in good yields and at low cost through chemical synthesis, beside than from natural sources

Mating behaviour and dual mode communication of Pear Psylla CACOPSYLLA PYRI

Cacopsylla pyri (L.) (Hemiptera, Psyllidae) is one of the most important pests of European pear, and its management generally depends on the use of chemical insecticides, but C. pyri outbreaks are sometime observed. Ecological control strategies should be desirable and the knowledge of mating behavior is crucial to develop new ones. A multi-approaches research aimed to acquire knowledges about C. pyri mate finding. Electroantennographic (EAG) analyses and olfactometric bioassays were used to evaluate the activity of intraspecific semiochemicals on C. pyri. The EAG amplitudes revealed that volatile compounds, present in female cuticular extracts, elicited dose-dependent responses in males, indicating that these compounds were able to stimulate the male olfactory system. In behavioral bioassays, living females and female cuticular extracts, attracted summerform males in a highly significant manner. Gas chromatography-mass spectrometry revealed that 13-methylheptacosane, 11,13-dimethylheptacosane, 2-methylheptacosane and 3-methylheptacosane were found in larger amounts in female extracts than in male ones, which suggests their role in male attraction. In addition, a laser vibrometer device was used to detect a male-female substrate-born vibrations pattern during pre-copulatory period. The female vibrational signal was recorded as mp3 and conveyed, in loop using a minishaker, on pear shoots with C. pyri virgin pairs to interfere with the mating by masking the natural communications

Selection of lactic acid bacteria species and strains for efficient trapping of Drosophila suzukii

Monitoring of Drosophila suzukii is based on the use of effective traps and baits. The current baits are insufficient to provide efficient monitoring. The use of bacteria as bio-catalyzers to produce bioactive volatiles may improve flies’ attraction. Thus, we conducted this work to improve Droskidrink® bait’s attractiveness using lactic acid bacteria. (2) Different baits that were based on the use of Droskidrink® were assessed for flies’ attraction in a Droso-Trap® in a vineyard. Oenococcus oeni, Pediococcus spp., and Lactobacillus spp. were used. The performance of the most attractive species, O. oeni, inoculated into Droskidrink® was assessed in laboratory tests. The responses of female flies to volatiles produced by Droskidrink® with O. oeni strains were recorded by electroantennography. (3) Preliminary field assessment of baits recorded O. oeni as the most attractive species. Three strain groups showed adaptation to test conditions. Volatiles extracted by the headspace of baits inoculated with O. oeni, elicited electroantennographic responses from fly antennae. (4) Droskidrink® inoculated with O. oeni is a highly attractive bait for monitoring. These findings will be useful for improving the attractiveness of D. suzukii commercial baits based on the utilization of LAB volatiles in a strain-dependent manner