Influence of Grapevine Cultivar on the Second Generations of Lobesia botrana and Eupoecilia ambiguella

A traça-da-uva, Lobesia botrana, na Região Demarcada do Douro: Efeito da sub-região, ano, geração e casta, na intensidade do ataque da praga

A traça-da-uva, Lobesia botrana, é praga-chave da vinha na Região Demarcada do Douro (RDD). A sua importância económica, a par da necessidade de reduzir o uso de inseticidas de síntese na vinha, conferem relevância ao desenvolvimento de estratégias de proteção contra a praga, alternativas aos meios químicos. Incluem-se nestas estratégias, a seleção das castas, as medidas culturais e a confusão sexual. O seu adequado uso obriga a um aprofundado conhecimento do comportamento do inseto em relação a diversos parâmetros biológicos. Com o presente trabalho, pretendeu-se, através da análise de dados recolhidos entre 2000 e 2019, estudar a influência, na intensidade do ataque de L. botrana, na RDD, da sub-região, ano, geração e casta. Os resultados mostraram que, a intensidade do ataque da praga: i) foi, em geral, inferior no Douro Superior, comparativamente, quer ao Cima Corgo quer ao Baixo Corgo; ii) diferiu entre anos, na dependência das condições climáticas, mas tendencialmente diminuiu ao longo dos anos; iii) na primeira geração, em geral manteve-se em valores inferiores ao nível económico de ataque, enquanto nas restantes gerações se situou entre os limites estabelecidos para o mesmo (i.e. 1 – 10% cachos atacados); iv) as castas ‘Touriga Franca’, no caso das castas tintas, e ‘Malvasia Fina’, no caso das castas brancas foram, de entre as estudadas, as tendencialmente mais atacadas.

Side Effects of Sulfur Dust on the European Grapevine Moth Lobesia botrana and the Predatory Mite Kampimodromus aberrans in Vineyards

To reduce the impact of synthetic insecticides on human health and the environment, eco-friendly alternatives must be investigated. Knowledge of the side effects on pests and natural enemies of natural products applied to vineyards is very useful. Sulfur dust, which is used in vineyards to control powdery mildew, is investigated in laboratory and field bioassays for its effects on Lobesia botrana egg laying, egg hatching, and larval settlement. In field trials, the efficacy of sulfur dust against the two L. botrana carpophagous generations is compared with that of Bacillus thuringiensis and kaolin, and its side effects on the phytoseiid mite Kampimodromus aberrans are evaluated. In the bioassays, sulfur dust reduced female survival by 43%, egg laying by around 80%, egg hatching by 10%, and larval settlement by 55%. In field trials, sulfur dust caused a significant decrease in the number of L. botrana larval nests of both generations, even though the efficacy was lower than that of B. thuringiensis. No negative effects of sulfur dust on the predatory mite population density was observed. On the basis of these results, in the context of Integrated Pest Management strategies in vineyards, the activity of sulfur dust against L. botrana could be exploited by timing its application to the beginning of egg laying.

Tracking Short-Range Attraction and Oviposition of European Grapevine Moths Affected by Volatile Organic Compounds in a Four-Chamber Olfactometer

The identification of volatile organic compounds (VOCs) leading to short-range attraction and oviposition of the European grapevine moth Lobesia botrana and European grape berry moth Eupoecilia ambiguella (Lepidoptera: Tortricidae) is crucial in order to establish bait-based decision support systems for control of these pests. Therefore, we developed a method to measure the real-time behavioral response of female moths to VOCs using a four-chamber olfactometer coupled with a video tracking system. Ten synthetic VOCs were selected for this study: (S)-(−)-perillaldehyde, (E)/(Z)-linalool oxide, (±)-limonene, linalool, (E)-β-caryophyllene, α/β-farnesene, (−)-α-cedrene, methyl salicylate and cumene. The effect of VOCs on egg deposition was determined using a dual-choice oviposition test, whereas perception by female antennae was verified using electroantennography (EAG). During video tracking, females responded to volatile compounds emitted by grapevine with higher antennae and ovipositor activity than to air control. (E)/(Z)-linalool oxide, cumene and (S)-(−)-perillaldehyde released ovipositor activity of L. botrana, while the latter provoked oviposition. (R)/(S)-limonene affected ovipositor activity of E. ambiguella, whereas none of the VOCs tested attracted for oviposition. The results suggest that females have the ability to perceive specific VOCs by the antennae but also by the ovipositor, which could attract or repel for egg deposition.

Do Grapholita funebrana Infestation Rely on Specific Plum Fruit Features?

The effective control of the plum fruit moth, Grapholita funebrana (Lepidoptera: Tortricidae) still represents a difficult challenge for organic plum farming. Little information is available on the susceptibility of plum cultivars to this moth pest. We investigated the roles of several fruit parameters (i.e., shape, volume, hardness, fruit colour, and physiochemical properties) on the susceptibility of four different plum cultivars (Angeleno, Friar, President and Stanley) to G. funebrana attack. Field data demonstrated the importance of some fruit parameters (i.e., elongation index, sugar degree, titratable acidity, cover colour percentage) on susceptibility to G. funebrana infestation. Under laboratory conditions, colour and shape had a significant role in determining the time spent on false fruits, i.e., female moths preferred yellow and rounded fruits over elongated red or green fruits. Angeleno (yellow and rounded fruits) and Stanley (green and elongated fruits) were the most and least susceptible cultivars, respectively. Overall, this study adds useful knowledge about plum cultivar susceptibility to G. funebrana. Information reported here may be useful to improve integrated pest management strategies both in conventional and organic orchards because the use of less susceptible cultivars may reduce insecticidal treatments, limiting the development of resistance in target insects and the harmful side effects on beneficial species.