Abiotic Factors Affecting Canola Establishment and Insect Pest Dynamics

Table 3

F values from nonparametric analysis of grouped densities of aphids and thrips on canola plants.

Aphids	Dec	Jan	Feb	Mar	Apr	All months
Seed	0.90	17.23^(***)	13.33^(***)	4.14^(*)	1.22	15.89^(***)
Seed treatment	1.42	30.71^(***)	26.43^(***)	2.71	1.36	20.20^(***)
Treatment	0.78	17.42^(***)	14.29^(***)	2.40	0.86	12.28^(***)
Site	4.58^(*)	1.32	9.81^(**)	0.49	2.67	12.65^(***)
Season	10.03^(**)	2.38	1.59	5.78^(*)	17.91^(***)	4.98^(*)
Thrips
Seed	0.55	0.69	2.51	0.06	0.08	1.35
Seed treatment	<0.00	0.04	1.92	2.25	<0.00	1.63
Treatment	0.37	0.60	1.49	1.23	0.05	1.01
Site	0.10	1.72	3.61	0.61	1.31	0.08
Season	8.78^(**)	18.69^(***)	9.76^(**)	70.81^(***)	86.68^(***)	13.83^(***)

Canola plants were planted in September and emerged in November. Insect data were collected from December to April in two growing seasons and at two field locations. Aphid counts were divided into three classes (class 0 = plants without aphids (38% of observations), class 1 = 1–15 aphids per plant (32% of observations), and class 2 > 15 aphids per plant (30% of observations)). Thrips data were divided into presence (class = 1; 25% of observations) and absence (class = 0; 75% of observations). *: significant difference at the 0.05 level, **: significant difference at the 0.01 level, and ***: significant difference at the 0.001 level.