Page 9 - Volume 5, Issue 1, January 2012

© Benaki Phytopathological Institute
Integrated management of the red palm weevil 7
values, mean of 95.4 ± 2.7 %, for at least 45
days after application (Llácer et al., 2012). In a
field assay, two applications of imidacloprid
OD per year successfully reduced mortality
of P. canariensis palms to less than 27% com-
pared to more than 84% for untreated con-
trol palms (Dembilio et al., 2010a). Similar re-
sults were obtained by Tapia et al. (2011) in
Southern Spain.
3.2.1.2.Insecticidal paints
The efficacy of an insecticidal paint
based on chlorpyrifos and pyriproxyfen
(1.5% and 0.063%, respectively) in a micro-
encapsulated formulation was also studied
by our group (Llácer et al., 2010). This insec-
ticidal paint was applied on the stipe and
the base of the fronds of palms. Laborato-
ry results showed that pyriproxyfen had no
effect against R. ferrugineus when applied
in this microencapsulated formulation and
chlorpyrifos was the responsible of the ef-
ficacy of this product against the weevil. In
semi-field assays, the paint was highly effec-
tive as preventive treatment. However, it was
dismissed as curative insecticide. One single
application of this paint could prevent infes-
tation for up to 6 months with a mean effi-
cacy of 83.3%.
3.2.2. Biotechnological control:
semiochemicals
A very important component of any
strategy against R. ferrugineus is mass trap-
ping of adults using food baits. Ferrugine-
ol (4-methyl-5-nonanol) is the major aggre-
gation pheromone of the red palm weevil
(Hallett et al., 1993) and has been used in
conjunction with 4-methyl-5-nonanone
(Abozuhairah et al., 1996) in mass-trapping
programs which are widely practiced in sev-
eral countries where red palm weevil is a
problem (Abraham and Kurian, 1973; Hallett
et al., 1993; Vidyasagar et al., 2000). Because
(a) a trap set in an uninfested area can easily
lead to its infestation by weevils responding
to the attractive plumes coming from the
trap and (b) a trap can highly increase the in-
cidence of R. ferrugineus in an area if neigh-
boring palms are not adequately protected,
in Spain, mass trapping is only allowed un-
der direct supervision of the local Depart-
ment of Agriculture.
3.2.3. Biotechnological control: SIT
As a first step towards developing the
Sterile Insect Technique (SIT) against R. fer-
rugineus , Al-Aydeh and Rasool (2010) stud-
ied the influence of gamma radiation on its
mating behavior, and the efficacy of SIT un-
der different levels of relative humidity. No
adverse effects of gamma radiation were
observed on the mating behavior parame-
ters of theweevil. Furthermore, weevils were
sexually stimulated during aggregation.
However, as this weevil mates several times
during its lifetime and its mass rearing is
very expensive, the usefulness of this tech-
nique in this case remains quite doubtful.
3.2.4. Biological control
Reginald (1973) suggested that natu-
ral enemies do not play an important part
in controlling R. ferrugineus and few stud-
ies have been conducted on Rhynchopho-
rus spp. natural enemies (Faleiro, 2006; Mur-
phy and Briscoe, 1999). There were some
attempts in the laboratory and field us-
ing the predatory earwig Chelisoches morio
(Fabricius) (Dermaptera: Chelisochidae) in
India (Abraham and Kurian, 1973). Howev-
er, it did not provide a measurable impact
on the weevil. Although various mites have
been reported in India as parasites of R. fer-
rugineus (Nirula, 1956; Peter, 1989), their im-
pact on the population needs to be deter-
mined. Gopinadhan et al. (1990) reported
that a cytoplasmic polyhedrosis virus infect-
ed all stages of the weevil in Kerala (India).
Infected mature-larval stages resulted in de-
formed adults and severe suppression of the
host population. In addition to these results,
both entomopathogenic nematodes (EPN)
and fungi (EPF) can provide an alternative to
chemical control of R. ferrugineus (Dembil-
io et al., 2011b; Dembilio et al., 2010a; Dem-
bilio et al., 2010b; Faleiro, 2006; Llácer et al.,
2009; Tapia et al., 2011). Unlike EPNs, EPFs
infect the host by contact, then germinate
and penetrate the insect cuticle. The host