Effects of neem on adults of Eretmocerus warrae (Hym., Aphelinidae), a parasitoid of Bemisia tabaci (Horn., Aleyrodidae) in tropical horticulture systems

Abstract

Side effects of two commercial neem products, NeemAzal-T/S (1% azadirachtin) as foliar application and NeemAzal-U (17% azadirachtin) as soil application were tested in laboratory bioassays against about-to-emerge adults and adults of an aphelinid, Eretmocerus warrae (EW) an efficient parasitoid of the whitefly Bemisia tabaci (WF) in Thailand. Hatching rates of unparasitised WF were reduced by foliar treatments with NeemAzal TS from 84% (control) to 16% (10ml l -1 ), by soil application with NeemAzal-U from 84% (control) to 63% (3.0 g l -1 ). Parasitoid emergence was affected in a dose-dependent manner. Whereas 80% of the EW adults hatched in tap-water treated controls after foliar treatments of pupa with NeemAzal-T/S hatching rates decreased to 50 and 24% at 5 and 10 ml l -1 dose rates respectively. In contrast, the soil application of NeemAzal-U did not affect the emergence of parasitoids. In both neem treatments longevity of the hatched adults was the same for both sexes, and no alternation in sex-ratio was detected. The longevity of the adult parasitoids was only affected after 36 hrs contact with high dose residues of NeemAzal-T/S (10-15 ml l -1 ) in a dry-residue bioassay test. The experiments indicate that ecto-endo parasitoids are principally highly vulnerable to neem but show in addition that soil application could reduce negative side effects compared to plant spraying and hence improve selectivity.

Efectos de insecticidas botánicos comerciales en Tamarixia radiata, un ectoparasitoide de Diaphorina citri

“…En relación al Neem PHC, se tiene registrado como un producto de toxicidad baja en tratamientos residuales sobre Tamarixia triozae (Burcks) (Luna-Cruz et al 2011). Se ha demostrado que la residualidad de insecticidas botánicos basados en azadiractina, suelen ser de bajo impacto en especies de himenópteros parasitoides (Xu et al 2004, Kumar et al 2010, Sidi et al 2013). En contraste, los resultados muestran que la exposición residual al CinnAcar no fue letal para T. radiata, y aunque no se encontraron antecedentes de los efectos residuales de este producto en la mortalidad de parasitoides, los hallazgos coinciden con lo obtenido por Buczkowski et al (2005), quienes evaluaron un insecticida compuesto de Cinnamaldehído en Monomorium pharaonis (Hymenoptera: Formicide) y encontraron que no se elevó de forma signi cativa los niveles de mortalidad bajo tratamientos residuales.…”

Ecosmart Biorational Insecticides: Alternative Insect Control Strategies

“…Rotenone is used as insecticide and mainly a fish poison to paralyze fish, causing them to surface and be easily captured, but there is a growing concern about its safety and its relation to Parkinson's disease (Betarbet et al, 2000). For more niceties about traditional botanical insecticides, see Ware & whitecare (2004), Isman (2005Isman ( , 2006Isman ( , 2010, Isman & Akhtar (2007), Gilbert & Gill (2010), Kumar et al (2010), Dubey (2011), and Mehlorn (2011).…”

“…Ecologically, azadirachtin is non toxic to fish (Wan et al, 1996), natural enemies and pollinators (Naumann & Isman, 1996), birds, other wild life, and aquatic organisms as azadirachtin, breaks down in water within 50-100 h. It is harmless to non-target insects (bees, spiders, and butterflies). The effect of azadirachtin on natural enemies is highly variable (Hohmann et al, 2010, Kumar et al, 2010. Environmentally, azadirachtin induce no accumulations in the soil, no phytotoxicity and accumulation seen in plants, and no adverse effect on water or groundwater (Mehlhorn, 2011).…”

“…Moreover, the oil can turn rancid ( De Groot, 1991) and is easily contaminated with aflatoxins, so contaminated neem seeds with aflatoxin should not be picked from the ground but seeds that are greenish yellow in color should be picked from the trees or swept regularly under the tree (Gunasena & Marambe, 1998). Ecto-endo parasitoids vulnerable to neem but soil application could reduce negative side effects compared to plant spraying and hence improve selectivity (Kumar et al, 2010). Treating the host with neem before parasitism was less deleterious to wasp emergence, especially for Trichogrammatoidea annulata (Hohmann et al, 2010).…”

“…Treating the host with neem before parasitism was less deleterious to wasp emergence, especially for Trichogrammatoidea annulata (Hohmann et al, 2010). For more details about safety of neem, see Boeke et al (2004), Mehlhorn (2011), Kumar et al (2010), andHomanni et al (2010).…”