Numerous studies have demonstrated that entomophagous arthropods use herbivore-induced plant volatile (HIPV) blends to search for their prey or host. However, no study has yet focused on the response of nocturnal predators to volatile blends emitted by prey damaged plants. We investigated the olfactory behavioral responses of the night-active generalist predatory earwig Doru luteipes Scudder (Dermaptera: Forficulidae) to diurnal and nocturnal volatile blends emitted by maize plants (Zea mays) attacked by either a stem borer (Diatraea saccharalis) or a leaf-chewing caterpillar (Spodoptera frugiperda), both suitable lepidopteran prey. Additionally, we examined whether the earwig preferred odors emitted from short- or long-term damaged maize. We first determined the earwig diel foraging rhythm and confirmed that D. luteipes is a nocturnal predator. Olfactometer assays showed that during the day, although the earwigs were walking actively, they did not discriminate the volatiles of undamaged maize plants from those of herbivore damaged maize plants. In contrast, at night, earwigs preferred volatiles emitted by maize plants attacked by D. saccharalis or S. frugiperda over undamaged plants and short- over long-term damaged maize. Our GC-MS analysis revealed that short-term damaged nocturnal plant volatile blends were comprised mainly of fatty acid derivatives (i.e., green leaf volatiles), while the long-term damaged plant volatile blend contained mostly terpenoids. We also observed distinct volatile blend composition emitted by maize damaged by the different caterpillars. Our results showed that D. luteipes innately uses nocturnal herbivore-induced plant volatiles to search for prey. Moreover, the attraction of the earwig to short-term damaged plants is likely mediated by fatty acid derivatives.
CITATIONS 0 READS 205 9 authors, including: Some of the authors of this publication are also working on these related projects: Pheromone of the pantropical ambrosia beetle Euplatypus parallelus (Curculionidae, Platypodinae) View project Melon pest control tactics in the northeastern brazilian semiarid (Project funded by Embrapa) View project AbstractEmission of herbivore-induced plant volatiles (HIPVs) can differ according to the type of herbivory and the plant development stage, ultimately affecting recruitment of the natural enemy. Little is known about plant defenses induced at the flowering stage by phloem-feeding insects. We investigated the olfactory preference of Encarsia desantisi parasitoids and the chemical profile of flowering melon plants induced or not by the phloem-feeding of Bemisia tabaci whiteflies. In addition, we tested whether the parasitoids were attracted to synthetic defensive HIPVs, which mimicked whitefly-infested flowering melons. The parasitoids recognized volatiles from undamaged melons but preferred the scent of host-infested melons in olfactometry assays. Amounts of most individual volatiles did not differ between plant treatments; however, only whitefly-induced melons released methyl salicylate and tetradecane, compounds known to attract parasitoids. Interestingly, grouping volatiles by chemical classes revealed that whitefly-infested melon released larger amounts of monoterpenes and smaller amounts of benzenoids than undamaged melons, which might underlying the parasitoid attraction and indicate a possible trade-off between defensive and reproductive defenses at the melon flowering stage. Additionally, E. desantisi preferred the mix of synthetic and defensive HIPVs over hexane (control), opening a new avenue for further investigations in using olfactory lures for B. tabaci biological control. This study is the first report of induced defenses in melon plants and their mediation in a tritrophic interaction, as well as the first record of E. desantisi behavioral preference for HIPVs.
Se diagnosticó las plagas y enfermedades en plantaciones de Tectona grandis L.F (Teca) en la zona de Balzar, provincia del Guayas. Los objetivos fueron recolectar e identificar los insectos plagas y los agentes causales de enfermedades que se encuentran presentes en las plantaciones de Teca, determinar el nivel de incidencia y severidad de los problemas fitosanitarios. Se realizaron muestreos al azar mediante recorridos en transeptos y se establecieron parcelas de 500 m2 distribuidas según las superficies de las haciendas. Los insectos se recolectaron en época seca y lluviosa durante seis meses. Las plagas y enfermedades de mayor incidencia y severidad fueron: Hyadaphis erysimi y Hortensia similis (Homóptera); y Colletotrichum sp., Olivea tectonae y Ceratocystis sp. en época lluviosa. Atta sp. (Hymenóptera), Hemileuca maia y Scolytus sp. (Coleóptera); y Olivea tectonae en época seca.
RESUMO -O objetivo deste trabalho foi avaliar a eficiência de controle e os efeitos adversos de dois produtos à base de nim Azamax ® (Azadiractina A/B 12g/L) e Neemseto ® (Azadiractina A/B, Nimbina e Salanina 2,389 g/L) sobre o ácaro-rajado Tetranychus urticae e os predadores Phytoseiulus macropilis e Neoseiulus californicus em laboratório. Para o ácaro-rajado, foram consideradas as variáveis mortalidade, fecundidade, efeito ovicida e persistência biológica, enquanto para os fitoseídeos consideraram-se mortalidade e fecundidade. A mortalidade máxima observada para o ácaro-rajado foi de 89,7% e 91,5% para Azamax ® e Neemseto ® , respectivamente, na concentração de 0,5% após a reaplicação do produto no sétimo dia. Também foram observados efeitos adversos sobre a fecundidade e a viabilidade dos ovos quando tratados com os produtos comerciais (p.c.). A persistência biológica dos produtos foi de aproximadamente três dias após a pulverização. As formulações apresentaram seletividade em relação aos fitoseídeos, porém causaram redução da fecundidade dos mesmos. Termos para indexação: Azadirachta indica, ácaro-rajado, fitoseídeos. EFFECTS OF NEEM ON Tetranychus urticae KOCH (ACARI: TETRANYCHIDAE) AND THE PREDATORS Phytoseiulus macropilis (BANKS) AND Neoseiulus californicus (MCGREGOR) (ACARI: PHYTOSEIIDAE)ABSTRACT -The aim of the present study was to evaluate the efficiency of control and adverse effects of two neem based products: Azamax TM (Azadirachtin A/B 12g/L) and Neemseto TM (Azadirachtin A/B, Nimbin and Salanin 2,389 g/L) over two-spotted spider mite Tetranychus urticae and the predators Phytoseiulus macropilis and Neoseiulus californicus in laboratory. Effects over the mortality, fecundity, eggs and biological persistence of the two-spotted spider mite when treated with neem based products were evaluated. For the phytoseiids the effects on mortality and fecundity were evaluated. The maximum mortality of two-spotted spider mites rates observed were 89.7% and 91.5% for Azamax TM and Neemseto TM respectively, on the 0.5% concentration after reapplying the product on the seventh day. Adverse effects were also observed over the fecundity and viability of the eggs when treated with commercial products (c.p.). The biological persistence of the products was of approximately three days after being pulverized. The formulations present selectivity in relation to the phytoseiids, however they caused fecundity reduction.
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