and Integrated Pest Management - part - usaid

PESTICIDE RtNSIDULS IN1'III: IJ.PP[NESIM363
Table 9. Residues (ppm) of carbosulfan and carbofuran ol rice leaves.
Days Carbosulfan Carbofuran
0 3.5 0.3
1 2.2 2.5
2 0.8 1.0
3 0.2 0.2
5 0.01 0.08
7 ND 0,01
Carbosulfan
The fate of carbosulfan in a rice paddy environment was determined by
Tejada and Magallona (1985a). The extent of pollution through drainage water
was likewise monitored in a simulaited lake ecosystem. There were five spray
applications and the rates of uptake, distribution, and loss were determined
within a 30-day period. The results showed that carbosulfan was rapidly
converted to caihofuran in all components of the rice paddy ecosystem (water,
soils, snails, and rice plants) except on rice leaves where it remained up to 7 days
(Table 9). The partitioning pattern of carbosulfan in tle model ecosystem
(Tejada & Magallona 19851) 3 h after spray application was 72% in plants,
11.4% in water, 9.4% in snails, 1.1% in fish, and 0.03% in air. At equilibrium
(72 li), the partitioning pattern was 9.5% in plants, 19.1% in water, 40% in
snail, 0.4% in fish, and 0.03% in air. As carbosulfan residues decreased,
carbofuran levels increased. Rainfall contributed to its fast degradation. At
harvest time, carboluran residues were concen:rated on the leaves, followed by
the stem, and least on the grains. In paddy water, carbofuran was detected up to
15 days and repeated application did not result in the accumulation of carbofuran
residue. Maximum residue in paddy water ranged between 0.04 ppm and 0.07
ppm while the minimum ranged between 0.01 ppm and 0.03 ppm. This is
much lower than the thcoretical level of 0.4 ppm at prevailing water levels and
application rates,. Hydrolysis is the major degradation route (t 1/2 = 5-8 days);
occurring faster at higher p1-I and temperature. Carbofuran remained up to 30
days in the soil (t 1/2 = 4 days). Siddaramapa and Watanabe (1979) reported that
degradation of carbofuran in flooded soil was slow due to strong adsorption. In
P. luzonica, about 50% of carbofuran residues were obtained on the shell surface.
Maximum uptake was obtained one day after spray application with no detectable
residues in tie flesh after seven days.
In the simulated lake ecosystem, carbofuran was detected in water up to 15
(lays (t 1/2 = 3 days). The concentration in water (0.09 ppm) was biomagnified
in 7'. nilotica (10.5 ppm) up to 117 times. The c:arbofuran residue was still
detected 30 days after last spray application. In 1. aquatica,uptake was observed
up to 20 days but declined thereafter.
From the half-life values of carbofuran in fish (3.8 days), water (5.8 days),
soil (4 days), and rice plants (1.5 (lays), no parent compound or metabolite could