Cold treatment of “Hass” avocado (Persea americana (Lauraceae)) infested by Thaumatotibia leucotreta (Lepidoptera: Tortricidae) as an additional component of a systems approach

Figures & data

Table 1. Corrected percentage mortality (Abbott 1925) of immature Thaumatotibia leucotreta in “Hass” avocado overtime. Each replicate consisted of 25 fruit that were naturally infested by the first instar larvae

			Number of days at 2°C
Life stage (days)	Rep	0*	3	5	7	9	11	13	15	17	19
0 (eggs)	1	69.0 (280)	5.1	38.4	81.0	100	100	-	-	-	-
	2	71.5 (329)	0	56.3	82.6	100	100	-	-	-	-
3	1	0 (150)	2.3	16.3	28.3	90.9	100	-	-	-	-
	2	15.9 (147)	6.4	20.4	62.6	97.1	100	-	-	-	-
7	1	1.8 (39)	1.8	5.6	14.1	68.2	88.2	100	-	-	-
	2	3.6 (103)	1.6	2.5	14.1	91.2	100	-	-	-	-
8	1	2.9 (79)	0	2.4	21.5	80.3	100	100	-	-	-
	2	2.7 (71)	2.7	11.3	21.2	61.9	96.2	100	-	-	-
9	1	1.9 (70)	2.9	11.3	19.4	-	80.9	100	-	-	-
	2	0 (67)	3.3	14.9	23.6	71.4	95.2	100	-	-	-
10	1	2.1 (175)	0	19.3	38.2	85.5	94.7	98.5	100	-	-
	2	0 (122)	0	7.5	33.3	73.9	76.5	97.7	99.3	100	-
11	1	1.0 (94)	0	18.4	54.3	85.3	96.5	100	-	-	-
	2	1.7 (147)	1.7	4.1	24.1	65.1	94.3	97.9	99.4	99.3	100
12	1	1.2 (85)	4.9	22.9	41.5	73.2	100	95.3	100	-	-
	2	0 (195)	0	15.5	45.9	73.4	87.7	99.7	99.3	100	-
13	1	0 (90)	0	1.7	35.6	61.3	92.1	65.7	100	-	-
	2	0 (109)	0	9.4	22.0	25.6	70.8	68.7	100	-	-

*Actual mortality (%); numbers in parenthesis are the average number of larvae in replicate.

Table 2. Probit analysis detailing the number of days various aged immature Thaumatotibia leucotreta in “Hass” avocado were expected to survive after cold treatment of 2°C. Data were corrected for natural mortality (Abbott 1925)

	Mortality (days (CL)
Life stage (days)	90%	99.9%	Regression	Percentage of deviance
0 (eggs)	5.7 (5.4–6.0)	14.1 (13.2–15.1)	y = 0.2152 x + 0.0642	79.04
3	9.0 (8.8–9.4)	12.3 (11.8–13.8)	y = 0.5521 x – 3.69839	93.31
7	10.3 (10.0–10.3)	13.4 (12.9–14.0)	y = 0.58325 x – 4.72783	92.53
8	10.2 (10.0–10.8)	13.4 (12.9–14.1)	y = 0.56475 x – 4.58187	96.12
9	11.1 (10.5–11.4)	15.4 (14.7–16.6)	y = 0.42316 x – 3.41685	95.58
10	10.7 (10.5–11.2)	15.2 (14.6–15.8)	y = 0.408712 x – 3.10615	95.92
11	11.0 (10.7–11.4)	15.8 (15.2–16.6)	y = 0.379298 x – 2.90266	92.90
12	10.7 (10.4–11.0)	15.3 (14.8–16.0)	y = 0.392626 x – 2.29218	98.08
13	10.9 (10.5–11.3)	15.3 (14.7–16.0)	y = 0.409750 x – 1.37259	94.41

Table 3. Survival of 11 d old Thaumatotibia leucotreta in “Hass” avocado after 20 d cold treatment of 2°C

Replicate	Control			Treated
	Live larvae	Number of fruit	Average number of larvae /fruit	Number of fruit	Estimated number of larvae treated	Number of live larvae
1	2,971	400	7.43	989	7,348	1
2	4,224	320	13.75	1,031	14,176	0
3	2,896	309	9.37	873	8,180	0
Total	10,091	1,029	9.81	2,893	28,380	1