CEPAVE   05420
CENTRO DE ESTUDIOS PARASITOLOGICOS Y DE VECTORES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
SURVIVAL FOLLOWING POST-LEPIDOPTERAN INSECTICIDE APPLICATIONS IN SOYBEANS
Autor/es:
SOSA, M.A; ALMADA, M. S.; VITTI, D. E.; ZUIL, S.G.; LÓPEZ, R.
Lugar:
Durban
Reunión:
Congreso; WORLD SOYBEAN RESEARCH CONFERENCE IX; 2013
Institución organizadora:
World Soybean Research
Resumen:
The purpose of the refuge in a resistance management programme is to allow survival of
susceptible individuals to delay the development of resistant insects. The objective of this
study was to quantify the levels of survival at different levels of damage and insecticide
application. The experiment was carried out at INTA EEA Reconquista, Santa Fe (Argentina), in
a soybean crop (Munasqa, GM VIII) under no tillage with a 52cm row spacing. Treatments were
arranged in a randomized complete block design in plots of 41.6m2, with three replications. The
crop was exposed to natural attack by Lepidopteran pests. Treatments were: i) 1-5 no residual
insecticide (100 cc/ha cypermethrin 25%), ii) 6-10 residual insecticide (120 c/ha
methoxyfenozide 24% (IGR), applied when defoliation levels 5, 10, 15, 20 and 30% were
reached, regardless of the phenological state, and iii) 11 control treatment. Analyzing the
evolution of the percentage of leaf area damaged, treatments clearly differed and generated two
groups with different percentages of damage. The group less damaged, (treatments 1, 2, 6 and 7)
was maintained throughout the growing season below 10% defoliation, whereas the group with
the most damage (treatments 3, 5, 10, 9, 8 and 4) reached 35% defoliation at R1 and remained in
a range of 25- 35% at R2, which started to decline in R4-R5 to reach percentages of damage
similar to the less damaged group. The control treatment (11) accompanied the evolution of this
group, but extended its period of maximum defoliation to R3. The first group differed
significantly from other treatments and showed the lowest values (<10%) of average leaf area
damaged throughout the crop cycle. When comparing the number of larvae in the treatment
maintaining the percentage of leaf area damage of <10% (co-incident with the threshold set by
INTA of 8-10% leaf area damage at R3-R6) with the control treatment, this group can be
proposed as refuge management according to this threshold. This would generate 50% of
susceptible individuals in comparison to an untreated refuge without yield decreases. Treatments
1, 2, 6 and 7 produced the highest yield (3.662kg/ha average) and were statistically different
from other treatments using insecticide (2.637kg/ha average) and with the control (1.607 kg /
ha). In conclusion, the management of the refuge strip must be in accordance with thresholds
using INTA and IGR insecticides, so that the refuge produces the maximum number of
susceptible individuals without affecting grain production.2, with three replications. The
crop was exposed to natural attack by Lepidopteran pests. Treatments were: i) 1-5 no residual
insecticide (100 cc/ha cypermethrin 25%), ii) 6-10 residual insecticide (120 c/ha
methoxyfenozide 24% (IGR), applied when defoliation levels 5, 10, 15, 20 and 30% were
reached, regardless of the phenological state, and iii) 11 control treatment. Analyzing the
evolution of the percentage of leaf area damaged, treatments clearly differed and generated two
groups with different percentages of damage. The group less damaged, (treatments 1, 2, 6 and 7)
was maintained throughout the growing season below 10% defoliation, whereas the group with
the most damage (treatments 3, 5, 10, 9, 8 and 4) reached 35% defoliation at R1 and remained in
a range of 25- 35% at R2, which started to decline in R4-R5 to reach percentages of damage
similar to the less damaged group. The control treatment (11) accompanied the evolution of this
group, but extended its period of maximum defoliation to R3. The first group differed
significantly from other treatments and showed the lowest values (<10%) of average leaf area
damaged throughout the crop cycle. When comparing the number of larvae in the treatment
maintaining the percentage of leaf area damage of <10% (co-incident with the threshold set by
INTA of 8-10% leaf area damage at R3-R6) with the control treatment, this group can be
proposed as refuge management according to this threshold. This would generate 50% of
susceptible individuals in comparison to an untreated refuge without yield decreases. Treatments
1, 2, 6 and 7 produced the highest yield (3.662kg/ha average) and were statistically different
from other treatments using insecticide (2.637kg/ha average) and with the control (1.607 kg /
ha). In conclusion, the management of the refuge strip must be in accordance with thresholds
using INTA and IGR insecticides, so that the refuge produces the maximum number of
susceptible individuals without affecting grain production.