Insecticidal activity of Laurelia sempervirens (Ruiz & Pav.) Tul. essential oil against Sitophilus zeamais Motschulsky

Abstract

The maize weevil Sitophilus zeamais Motschulsky is a worldwide key pest of stored products. Usually contact insecticides or fumigants are used against it, but problems as toxic residues, human intoxications, and resistance have triggered the search for alternative control methods as the use of essential oils. The objective of this research was to assess under laboratory conditions, the insecticidal properties of Laurelia sempervirens (Ruiz & Pav.) Tul. essential oil against S. zeamais. In contact toxicity bioassay assessed treatments were 0 (control), 1.25, 2.5, 5.0, 10, 20, and 40 mL essential oil kg -1 grain and 0 (control), 25, 50, 75, 100, 125, 150, and 175 μL essential oil L -1 air in fumigant toxicity tests. The highest toxicity by contact activity was reached by concentrations higher than 10 mL essential oil kg -1 grain (100% mortality). The same treatments totally inhibit F1. The dose of 175 μL essential oil L -1 air showed a significant toxicity by fumigant activity causing 72.5% of dead insects. The other treatments did not surpass 5% mortality. In offspring effect (F1) bioassay, all treatments had an insect emergence significantly lower than the control but concentrations equal or higher than 10 mL essential oil kg -1 grain prevented the emergence of F1 during the 7 wk of bioassay. The residual effect of contact toxicity remained by 15 d. The treatments based on essential oil lead to a weight grain loss lower than control and germination was not affected. All assessed treatments showed repellent effect. The essential oil of L. sempervirens has promissory perspectives to maize weevil control.

Insecticidal activity of powder and essential oil of Cryptocarya alba (Molina) Looser against Sitophilus zeamais Motschulsky

“…These treatments values were significantly lower than the observed in the rest of treatments and did not differ with those of the control with emergences between 46% and 56% (Table 4). Our results agree with those observed in the evaluation of other essential oils from Chilean native plants as P. boldus (Betancur et al, 2010) and L. sempervirens (Torres et al, 2014). In both cases, the insect emergence begins in the week 5 and the higher concentrations of essential oil showed a lower F1.…”

“…Tul. (Monimiaceae) (Torres et al, 2014), Laureliopsis phillippiana (Looser) Schodde (Monimiaceae) (Ortiz et al, 2012), and Drimys winteri J.R. Forst. & G. Forst.…”

Essential Oils in Stored Product Insect Pest Control

“…For instance, several studies evaluate the toxicity by putting insect specimens on food grains treated with EOs. In this scenario, it is possible to hypothesize that EOs can act as contact insecticides, as well as they can exert ingestion toxicity when pests feed on the grains [35][36][37][38][39][40]. Few studies claimed to evaluate the ingestion toxicity of EOs.…”

“…Residual insecticide activity of EOs could prevent adult emergence from pupae or impair the complete development of the larval stages [38]. Indeed, residues of EOs could remain in contact with pupae or larvae for a prolonged time when EOs are applied to the growing media, thus interfering with insect metabolism.…”

VARIACIÓN ESTACIONAL DE LA REPELENCIA DE LOS ACEITES ESENCIALES DE MONIMIACEAE SOBRE Sitophilus zeamais Motschulsky (CURCULIONIDAE)

“…Al 8%, a pesar que en todas las estaciones de colecta se obtuvo un IR ≤ 0,5, que corresponde a repelencia alta, no hubo diferencia estadística entre estaciones (Tabla 3). Los resultados concuerdan con Torres et al (2015), quienes concluyeron que aunque no se encontraron diferencias estadísticas entre tratamientos, las mayores concentraciones de polvo de L. sempervirens presentaron mayor efecto repelente. Torres et al (2014) tampoco encontraron diferencias al evaluar la repelencia de varias concentraciones de aceite esencial de L. sempervirens sobre S. zeamais, aunque no se indica la época de muestreo.…”