Insecticida

RESEARCH

399

INSECTICIDAL ACTIVITY OF Peumus boldus Molina ESSENTIAL OIL
AGAINST Sitophilus zeamais Motschulsky
Jessica Betancur R.1, Gonzalo Silva A.1*, J. Concepción Rodríguez M.2, Susana Fischer G.1,
and Nelson Zapata S.M.1

ABSTRACT
In stored grains, the main agents diminishing production are insects, which can produce losses between 20% and
80% before harvest or under storage.The insecticidal properties of the essential oil of fresh leaves of Peumus boldus
Molina against maize weevil (Sitophilus zeamais Motschulsky) adults were determined under laboratory conditions.
The highest mortality (100%) was achieved at 4% concentration by contact with a treated glass surface. The same
concentration in impregnated corn (Zea mays L.) grain, resulted in 98.7% mortality.Mortality by fumigant action at 6
h was 100% with 35 µL oil in 0.15 L (air volume). Concentrations 1, 2 and 4% of essential oil produced 0% F1 adult
emergence. At 10 d of residual effect, the 4% concentration reached 63.7% mortality. All treatments were repellent
to adults of S. zeamais and corn grain germination was not affected by any treatment.
Key words: Maize weevil, boldus, stored grains,botanical insecticides.

INTRODUCTION
Cereal grains are staples in the diets of human beings and
domestic animals. Consequently, their conservation is
essential to have this basic food available on an ongoing
basis (Huang and Subramanyam, 2005). Grains in storage
are affected by several insect species that can destroy up
to 50% of the harvest in 6 months. As well, storage allows
the entranceof phytopathogenic organisms, such as
fungus or bacteria (Regnault, 1997). Synthetic pesticides
have been considered the most effective and accessible
means to control insect pests of stored products (Huang
and Subramanyam, 2005). However, their use can result
in the presence of residues in the grains (Sanna et al.,
2004).
The current trend is the search for and use of alternative
methodsto manage pests, which, in the economic context,
are effective without presenting the risks associated with
the use of conventional pesticides. One method consists of
using plants with insecticidal properties that can be used
as powder, extracts or oils (Mazzonetto and Vendramim,
Universidad de Concepción, Facultad de Agronomía, Av. Vicente
Méndez 595, Chillán, Chile. *Corresponding author(gosilva@udec.cl).
2
Colegio de Postgraduados, Programa de Entomología y Acarología,
km 36.5, Carretera México-Texcoco, Montecillo, Estado de México,
México.
Received: 25 May 2009.
Accepted: 17 September 2009.
1

2003). Botanic insecticides have been used traditionally
in developing countries to control pests of stored grain,
such as coleoptera of the genus Sitophilus (De Oliveira etal., 2003).
Aromatic plants have been used for both their
medicinal and insecticidal properties. Their characteristic
aroma derives from essential oils, many of which have
proven fumigant and contact activity, as well as ovicide,
anti-alimentary and repellent activity (Sanna et al., 2004).
One of the native Chilean plants that has been evaluated
as an insecticide in powdered form is boldo(Peumus
boldus Molina) (Monimiaceae) (Silva et al., 2003a;
2003b; 2005a; 2005b; 2006), a tree that can reach a height
of 20 m, with pruning it appears like a densely branched
bush (Vogel et al., 2005). The leaves contain alkaloids,
known together as boldine, which is attributed to having
antioxidant, anti-inflammatory and antipyretic properties
(Vogel et al., 1999). The leaves also haveessential oils.
Some 45 to 53% of the oil is composed of ascaridole, 1,8
cineole (30%), limonene, α-terpinol and terminen-4-ol
(Vogel et al., 2005). The compound 1,8 cineole is also
isolated from essential oil of plants such as Eucalyptus
globulus Labill, Gomortega keule (Molina) I.M. Johnst.,
Ocimum kilimandscharicum Baker ex Gürke, Ocimum
kenyense (Ayobangira), Ocimum basilicum L. and Salvia...