© Benaki Phytopathological Institute
Hellenic Plant Protection Journal
11:
62-70, 2018
DOI 10.2478/hppj-2018-0009
College of Agricultural and Food Sciences, King Faisal
University, Saudi Arabia.
* Corresponding author:
Lethal and sublethal effects of ten insecticides, used in
date palm production in Saudi Arabia, on the parasitoid
Trichogramma cacoeciae
M. Jamal Hajjar* and M. Al-Masoud
Summary
Lethal and sublethal effects of ten insecticides commonly used in date palm production
in Saudi Arabia were assessed in the laboratory against adults of
Trichogramma cacoeciae
, an impor-
tant egg parasitoid of the dried fruit moth
Ephestia calidella
. Bioassays were conducted
according to
the standard protocol of the International Organization for Biological Control IOBC/WPRS/Working
Group ‘Pesticides and Beneficial Organisms’. Our results showed that cypermethrin, deltamethrin, mal-
athion, phenthoate, methomyl, and carbosulfan were moderately harmful (IOBC Class 3) to the par-
asitoid. The botanical insecticides azadirachtin and matrine were moderately harmful (IOBC Class 3)
and slightly harmful (IOBC Class 2), respectively. The insect growth regulator pyriproxyfen was slight-
ly harmful, whereas bistrifluron was harmless (IOBC Class 1). Regarding sublethal effects, the parasit-
ism ratios compared to control were reduced by pyriproxyfen and azadirachtin to 49.0% and 58.0%, re-
spectively; hence they are classified as slightly harmful insecticides (IOBC Class 2). Bistrifluron and ma-
trine were harmless (IOBC Class 1) as parasitism ratios were reduced by 9.2% and 27.6%, respective-
ly. Longevity of adults exposed to bistrifluron and matrine (3.6 and 3.3 days, respectively) and to py-
riproxyfen and azadirachtin (1.7 and 1.3 days, respectively) was significantly lower than that in con-
trol (4.67 days). In semi-field tests, residues of most insecticides on leaves of tomato, a common host
plant of lepidopteran pests parasitized by
T. cacoeciae
, were considered moderately harmful to harm-
ful based on parasitoid mortality at 24 h post-treatment whereas they were slightly harmful at 7 and
14 days post-treatment.
Additional keywords
: longevity, mortality, parasitism, sublethal effects,
Trichogramma cacoeciae
, viability
aging impacts on date palms are restrict-
ed by the use of the parasitoid
Trichogram-
ma
cacoeciae
Marchal (Rubeai
et al.,
2003;
El-Shafie
et al.,
2017), which is commercially
available and the most commonly used nat-
ural enemy in biological control programs
(Hassan, 1993; Hassan
et al.
, 2000).
Nevertheless, application of insecticides
for the control of date palm pests cannot be
excluded and sustainable use is foreseen in
the frame of an Integrated PestManagement
plan. Therefore, there is an urgent need to
assess and quantify the risks of pesticides
against natural enemies of date palm pests
in order to minimize any adverse effects.
Pesticides may cause lethal effects to non-
target organisms in addition to sub-lethal
behavioral and development effects, such
as changes in rates of parasitism, longevity,
sex ratio, and adult emergence (Desneux
et
al.,
2007; Firake and Khan, 2010; Firake
et al.,
Introduction
Species of
Trichogramma
(Hymenoptera:
Trichogrammatidae) are important parasi-
toids in natural and agricultural ecosystems
and act as effective biocontrol agents of
lepidopteran pests in important crops such
as tomato, soybean and cruciferous plants
(Godfray, 1994; Beserra and Parra 1994;
Moezipour
et al
., 2008; Polaszek, 2010).
The dried fruit moth
Ephestia calidel-
la
(Guenée) (Pyralidae) is a pest of econom-
ic importance on date palm in Saudi Arabia,
attacking dates during harvest, storage and
packinghouse processing (El-Shafie
et al.,
2017). Development of the pest and its dam-
