Castruita-Esparza Gabriela, Bueno-Pallero Francisco Ángel, Blanco-Pérez Rubén, Dionísio Lídia, Aquino-Bolaños Teodulfo, Campos-Herrera Raquel
Instituto Politécnico Nacional , Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional Unidad Oaxaca (CIIDIR-IPN-OAXACA) , Hornos 1003 Colonia Nochebuena , Santa Cruz Xoxocotlán , Oaxaca, CP 71230 , México.
UDIT MED - Mediterranean Institute for Agriculture , Environment and Development , Pólo , Universidade do Algarve , Campus de Gambelas, Ed 8, 8005-139 , Faro , Portugal.
J Nematol. 2020;52:1-12. doi: 10.21307/jofnem-2020-072.
Entomopathogenic nematodes (EPNs) are excellent biological control agents. Although traditionally EPN application targeted belowground insects, their aboveground use can be supported if combined with adjuvants. We hypothesized that EPN infective juveniles (IJs) could be combined with plant-based oils as adjuvants, without decreasing their efficacy against insect larvae under various scenarios. Specifically, our objectives were to evaluate the activity of (Nematoda: Steinernematidae) when mixed with two plant-based oils (coconut and olive oils) and maintained at different temperatures and times, or combined with entomopathogenic fungi. First, we evaluated how these oils affected IJ survival and virulence against last instar (Lepidoptera: Pyralidae) larvae when maintained at five different temperatures (4, 8, 14, 20, and 24°C) and five incubation times (1, 3, 7, 14, and 21 days), using water as control treatment. Second, we evaluated virulence when combined with these two oils as well as with water (control) and combined with the entomopathogenic fungi (EPF), (Hypocreales: Clavicipitaceae). Infective juvenile survival was higher in coconut than olive oil and water mixtures up to 7 days at 4°C. Conversely, olive oil supported higher larval mortality than coconut oil at 4 to 20°C and 14 days. Similarly, the number of days needed to kill insect larvae increased at extreme temperatures (4 and 24°C) after 14 days. Finally, the EPN + EPF combination showed an additive effect compared to EPN and EPF single treatments. Our findings indicate that our plant-based oil mixtures maintain viable IJs at moderate temperatures and up to 7 to 14 days, and can be used in single EPN mixtures or combined with EPF. Entomopathogenic nematodes (EPNs) are excellent biological control agents. Although traditionally EPN application targeted belowground insects, their aboveground use can be supported if combined with adjuvants. We hypothesized that EPN infective juveniles (IJs) could be combined with plant-based oils as adjuvants, without decreasing their efficacy against insect larvae under various scenarios. Specifically, our objectives were to evaluate the activity of (Nematoda: Steinernematidae) when mixed with two plant-based oils (coconut and olive oils) and maintained at different temperatures and times, or combined with entomopathogenic fungi. First, we evaluated how these oils affected IJ survival and virulence against last instar (Lepidoptera: Pyralidae) larvae when maintained at five different temperatures (4, 8, 14, 20, and 24°C) and five incubation times (1, 3, 7, 14, and 21 days), using water as control treatment. Second, we evaluated virulence when combined with these two oils as well as with water (control) and combined with the entomopathogenic fungi (EPF), (Hypocreales: Clavicipitaceae). Infective juvenile survival was higher in coconut than olive oil and water mixtures up to 7 days at 4°C. Conversely, olive oil supported higher larval mortality than coconut oil at 4 to 20°C and 14 days. Similarly, the number of days needed to kill insect larvae increased at extreme temperatures (4 and 24°C) after 14 days. Finally, the EPN + EPF combination showed an additive effect compared to EPN and EPF single treatments. Our findings indicate that our plant-based oil mixtures maintain viable IJs at moderate temperatures and up to 7 to 14 days, and can be used in single EPN mixtures or combined with EPF.
昆虫病原线虫（EPNs）是优秀的生物防治剂。尽管传统上EPN的应用针对地下昆虫，但如果与佐剂结合，其在地上的应用也能得到支持。我们假设EPN感染性幼虫（IJs）可以与植物油作为佐剂结合，而不会在各种情况下降低其对昆虫幼虫的效力。具体而言，我们的目标是评估（线虫纲：斯氏线虫科）与两种植物油（椰子油和橄榄油）混合并在不同温度和时间下保存，或与昆虫病原真菌结合时的活性。首先，我们评估了这些油在五个不同温度（4、8、14、20和24°C）和五个孵育时间（1、3、7、14和21天）下对IJs存活和对末龄（鳞翅目：螟蛾科）幼虫毒力的影响，以水作为对照处理。其次，我们评估了与这两种油以及与水（对照）结合并与昆虫病原真菌（EPF），（肉座菌目：麦角菌科）结合时的毒力。在4°C下保存长达7天时，椰子油中感染性幼虫的存活率高于橄榄油和水的混合物。相反，在4至20°C和14天时，橄榄油导致的幼虫死亡率高于椰子油。同样，在极端温度（4和24°C）下，14天后杀死昆虫幼虫所需的天数增加。最后，与EPN和EPF单一处理相比，EPN + EPF组合显示出相加效应。我们的研究结果表明，我们的植物油混合物在适度温度下可使存活的IJs保持7至14天，并且可用于单一EPN混合物或与EPF结合使用。昆虫病原线虫（EPNs）是优秀的生物防治剂。尽管传统上EPN的应用针对地下昆虫，但如果与佐剂结合，其在地上的应用也能得到支持。我们假设EPN感染性幼虫（IJs）可以与植物油作为佐剂结合，而不会在各种情况下降低其对昆虫幼虫的效力。具体而言，我们的目标是评估（线虫纲：斯氏线虫科）与两种植物油（椰子油和橄榄油）混合并在不同温度和时间下保存，或与昆虫病原真菌结合时的活性。首先，我们评估了这些油在五个不同温度（4、8、14、20和24°C）和五个孵育时间（1、3、7、14和21天）下对IJs存活和对末龄（鳞翅目：螟蛾科）幼虫毒力的影响，以水作为对照处理。其次，我们评估了与这两种油以及与水（对照）结合并与昆虫病原真菌（EPF），（肉座菌目：麦角菌科）结合时的毒力。在4°C下保存长达7天时，椰子油中感染性幼虫的存活率高于橄榄油和水的混合物。相反，在4至20°C和14天时，橄榄油导致的幼虫死亡率高于椰子油。同样，在极端温度（4和24°C）下，14天后杀死昆虫幼虫所需的天数增加。最后，与EPN和EPF单一处理相比，EPN + EPF组合显示出相加效应。我们的研究结果表明，我们的植物油混合物在适度温度下可使存活的IJs保持7至14天，并且可用于单一EPN混合物或与EPF结合使用。
