Toxicological and biochemical studies for chlorpyrifos insecticide on some mosquito larvae and their associated predators

Figures & data

Table 1. Predominance of mosquito larvae from different breeding sites in El-fayoum

species sit	Culex Pipiens	Culex antennatus	Anopheles Phareonsis	Ochlerotatus caspius.	Caenis spp	Pantala flavescens	T (°C)	pH	DO (mg/L)	TDS (mg/L)	EC (μS/cm)
1	1304	59	2139	1110	50	67	19.9	8.1	14.1	1.09	1.81
2	1150	-	15	1220	40	12	18	8.3	26.5	1.02	1.82
3	892	15	341	890	-	25	17.5	7.8	25.1	1.01	2.11
4	225	11	111	220	13	34	15.8	8.5	14.4	1.24	2.48
Total No.	3571	85	2958	3440	103	138

T. Temperature, pH. Potential hydrogen, Do. Dissolved oxygen., TDS. Total dissolved solid., EC. Electrical conductivity.

Table 2. Predatory potency of caenis stephens (mayfly) naiads over the mosquito larvae and pupae of three mosquito species after 24 h

Mosquito species prey	Consumed immature stages (Mean ± SD)
	1^st larval instar	2^nd larval instar	3^rd larval instar	4^th larval instar	Pupal
Anopheles pharoensis	18 ± 0.82	11.8 ± 1.3	8.5 ± 1.3	2 ± 0.82	0 ± 0
Ochlerotatus caspius	15.3 ± 1	12 ± 0.82	9.3 ± 1	1 ± 0.82	0 ± 0
Culex pipiens	13.5 ± 1.3	11.5 ± 1.3	7.8 ± 1.7	0 ± 0	0 ± 0

Table 3. Predatory potency of pantala flavescens (dragonfly) naiads over the mosquito larvae and pupae of three mosquito species after 6 hrs

Mosquito species	Consumed immature stages (Mean ± SD)
	1^st larval instar	2^nd larval instar	3^rd larval instar	4^th larval instar	Pupal
Culex pipiens	6 ± 0.82	9.5 ± 0.58	7.8 ± 0.96	3.5 ± 0.58	0 ± 0
Anopheles pharoensis	8 ± 0	7 ± 0.82	8 ± 0.82	3.5 ± 0.58	0 ± 0
Ochlerotatus caspius	4 ± 0.82	3.5 ± 0.58	6.8 ± 0.96	5.8 ± 0.96	0 ± 0

Table 4. Predatory potency of pantala flavescens (dragonfly) naiads over the mosquito larvae and pupae of three mosquito species after 24 h

Mosquito species	Consumed immature stages (Mean ± SD)
	1^st larval instar	2^nd larval instar	3^rd larval instar	4^th larval instar	Pupal
Culex pipiens	32.5 ± 2.1	37.8 ± 2.23	50 ± 1.83	17.5 ± 1.73	9.8 ± 1.71
Anopheles pharoensis	40.3 ± 1.3	42 ± .82	46.8 ± 1.5	21 ± 1.8	6.5 ± 1.3
Ochlerotatus caspius	33.3 ± 3.9	30.3 ± 7.4	39.5 ± 1.3	14.5 ± 1.3	8.3 ± 0.95

Figure 1. Toxicity of the chlorpyrifos insecticide against mosquito larvae and associated aquatic predators.

Table 5. Effect of chlorpyrifos on aChE level in mosquito larvae and associated aquatic predators

Species	AChE activity ± SE (μg AChBr/min/mg protein)
	Control population	Treated population
Culex pipiens	2.94 ± 0.11^a	6.1 ± 0.15 ^a
Ochlerotatus caspius	1.38 ± 0.1^b	2.2 ± 0.2 ^b
Anopheles pharoensis	0.8 ± 0.1 ^b	1.3 ± 0.15 ^b
Pantala flavescens	3.6 ± 0.1 ^a	5.4 ± 0. 3 ^a

a: means that there is significant difference between control and treated group (p < 0.05).

b: means that there is no significant difference between control and treated groups (p > 0.05).

Table 6. Effect of chlorpyrifos on GST level in target and non-target species

Species	GST activity ± SE (mmol sub. conjugated/min/mg protein)
	Control	chlorpyrifos
Culex pipiens	2 ± 0.12^a	3 ± 0.11 ^a
Ochlerotatus caspius	1.8 ± 0.1 ^b	2 ± 0.1 ^b
Anopheles pharoensis	1.72 ± 0.3 ^b	1.78 ± 0.1 ^b
Pantala flavescens	2.7 ± 0.13 ^a	3.62 ± 0.1 ^a

a: means that there is significant difference between control and treated group (p < 0.05).

b: means that there is no significant difference between control and treated groups (p > 0.05).