Ovicidal and larvicidal effect of bifenthrin and malathion on Amorbia

Ovicidal and larvicidal effect of bifenthrin and malathion on
leafroller Amorbia sp. (Lepidoptera: Tortricidae)
Alma M. Espino1, Ana M. Martínez1, José I. Figueroa1, Ángel Rebollar2, José
L. Morales3, Javier Valle4, Juan M. Chavarrieta1 y Samuel Pineda1
1
Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás
de Hidalgo, Km. 9.5 Carr. Morelia-Zinapécuaro. 58880 Tarímbaro, Michoacán México.
2
[email protected]. Universidad Autónoma Chapingo, Periférico Paseo de la República No.
3
1000. 58170 Morelia, Michoacán, México. Facultad de Agrobiología, Universidad Michoacana de
San Nicolás de Hidalgo, Paseo Lázaro Cárdenas esquina Berlín, Colonia Viveros, Uruapan,
4
Michoacán, México. ECOSUR, Apdo. Postal 36, Km. 2.5 Carr. Antiguo Aeropuerto, CP. 30700
Tapachula, Chiapas, México.
The toxicity of bifenthrin (Talstar®) and malathion (Malphus®) was tested against
eggs of two different age classes (48 h and 6 d old) of two populations of the
leafroller, Amorbia sp. (Lepidoptera: Tortricidae) collected in conventional and
organic crops of blackberries (Rubus sp.) at Los Reyes and Tocumbo, Michoacán,
Mexico, respectively. High density polyethylene papers strips containing egg
masses were cut in small circles (15 mm diam) and dipped for 5 s in seven
different concentrations for each insecticide (0, 0.1, 1, 10, 50, 100, 200, and 500
mg [AI]/liter). Concentrations were diluted in water plus the surfactant Tween at
0.01%. After drying, the polyethylene circles papers containing treated egg
masses were transferred individually to ventilated plastic cups (4 cm x 6 cm). Each
treatment was replicated four times (a repetition = a mass eggs). Egg mortality
was assessed 5 days after hatching. 80 larvae from each treatment were selected
randomly from larvae that emerged on the first day of hatching, placed on
semisynthetic diet, kept in four plastic cups, and observed daily during five days to
determinate larval mortality. Bifenthrin and malathion caused significant
differences in egg mortality in the two age classes (48-h- [F = 8.44, P = 0.000] and
6-d-old [F = 2.22, P=0.03] for organic population; and 48-h- [F=2.90, P=0.007] and
6-d-old [F=2.65, P=0.01] for conventional population). Median lethal concentration
(LC50) obtained for organic (27.95 and 32.48 mg a.i/liter, for larvae that hatched
from 48-h- and 6-d-old eggs, respectively) and conventional population (29.74 and
25.48 mg a.i/liter for larvae that hatched from 48-h- and 6-d-old eggs, respectively)
were not significantly different. Mortality caused by malathion was between 4947% and 21-17% for larvae hatched from eggs of two ages bioassayed of organic
and conventional populations, respectively.
Key words: Amorbia sp., chemical insecticides, Rubus sp.
Support: To PIFI 2013, CIC-UMSNH, and CONACYT for the scholarship to A. M.
Espino.