Page 54 - Volume 2,Issue 2, July 2009

Introduction

Beetles of theCoccinellidae family are among

the most common aphid predators (5, 8, 10).

However, their conservation in agroecosys-

tems is limited by the extensive use of insec-

ticides. Predatory coccinellids are likely to be

exposed to a great number of insecticides

while foraging in the field. More specifically,

they can be exposed to insecticides direct-

ly during pesticide applications or indirect-

ly by contacting insecticide residues while

foraging on sprayed surfaces or by consum-

ing prey exposed to insecticides. Concern-

ing the significant role of coccinellids and

other natural enemies in aphid biocontrol,

the use of more selective insecticides in in-

tegrated pest management (IPM) strategies

is helpful to the conservation of natural en-

emies (4). The most suitable insecticides are

those with high toxicity to pests and no tox-

ic effects on natural enemies (18, 19). Thus,

the impact of any compound used during

1

Department of Plant Production, ΤΕΙ of Epirus, Kos-

takioi Artas, 47100 Arta, Greece

2

Laboratory of Agricultural Entomology, Department

of Entomology and Agricultural Zoology, Benaki Phy-

topathological Insitute, 8 St. Delta Str., 145 61, Kifissia,

Athens, Greece

Corresponding author:

D.Papachristos@bpi.gr

Hellenic Plant Protection Journal

2:

101-106, 2009

Toxic effects of insecticide residues on three aphidophagous

coccinellid species

Ι. Katsarou

1

, A. Martinou

2

, D.P. Papachristos

2

and D. Zoaki

1

Summary

The toxicity of 1- and 8-day residues of three insecticides (imidacloprid, thiacloprid and

methomyl) was tested in the laboratory against the larvae (first and third instars) and adults of the

predacious coccinellids

Ceratomegilla undecimnotata

(Schneider)

, Oenopia conglobata

L. and

Propylaea

quatuordecimpunctata

L. Predators were placed for 24 h on broad bean leaves sprayed with the tested

insecticides at the recommended doses. Larval mortality was checked 1 day after exposure, upon pu-

pation and adult emergence. Adult mortality was checked 1, 10 and 20 days after exposure to insecti-

cides. Generally, 1- and 8-day residues of all insecticides tested caused high mortality (up to 100%) to

larvae and adults.

Additional keywords

: adults, imidacloprid, larvae, methomyl, thiacloprid, toxicity

crop protection on natural enemies should

be part of the essential evaluation process.

The lethal (mortality) and sublethal (de-

velopmental time, fecundity, locomotory

behavior) effects of insecticides on coccinel-

lid predators have been studied extensive-

ly (2, 7, 15, 17, 22, 25). However, susceptibil-

ity of coccinellids to insecticides may vary

significantly according to the insect species,

its developmental stage and the type of the

chemicals applied (21, 25). Although a great

number of studies have addressed the toxic

effects of insecticides against the coccinel-

lid predators, there is no data concerning

the effects of insecticides against some im-

portant coccinellid predators.

Ceratomegilla undecimnotata

(Schnei-

der) (Coleoptera: Coccinellidae) is a com-

mon European species that preys upon a

high number of aphid species in cultivated

and non-cultivated plants (10, 12, 13).

Propy-

laea quatuordecimpunctata

L. (Coleoptera:

Coccinellidae), a widely distributed Palearc-

tic aphidophagous species that has been es-

tablished in Canada and has spread into the

United States, preys upon numerous eco-

nomically important aphids on a wide range

of crops (6, 9, 16, 23).

Oenopia conglobata

L.

(Coleoptera: Coccinellidae) is also a wide-

spread coccinellid predator in Europe and