Table 2. Comparison of average population displacement of Heterorhabditis bacteriophora and Steinernema carpocapsae in the presence and absence of mobile and non-mobile hosts.

Species	H. bacteriophora			S. carpocapsae			Linear term	Quadratic term
	Presence and absence of non-mobile host
Host	3.60 ± 0.12			5.07 ± 0.41			**	**
	(Y = 0.809–0.014 Time - 1.658 x 10-4 Time2, r2 = 0.02; P = 0.87)			(Y = 3.974–0.069 Time + 0.081 x 10-2 Time2, r2 = 0.08; P = 0.05)
No host	3.37 ± 0.08			5.60 ± 0.45			**	**
	(Y = -0.184 + 0.027 Time - 2.564 x 10-4 Time2, r2 = 0.01; P = 0.15)			(Y = 5.611–0.101 Time + 4.387 x 10-4 Time2, r2 = 0.15; P < 0.01)
	F	Df	P	F	df	P
	2.37	1, 479	0.12	0.76	1, 479	0.38
	Presence and absence of mobile host
Host	5.30 ± 0.36			8.06 ± 0.59			**	**
	(Y = 13.217–0.351 Time + 0.003 Time2, r2 = 0.32; P < 0.01)			(Y = 4.737–0.097 Time + 6.558 x 10-4 Time2, r2 = 0.09; P = 0.02)
No host	5.40 ± 0.25			4.20 ± 0.17			**	**
	(Y = 2.298 + 0.080 Time + 5.272 x 10-4 Time2, r2 = 0.02; P = 0.31)			(Y = 1.213–0.026 Time + 4.862 x 10-4 Time2, r2 = 0.04; P = 0.08)
	F	Df	P	F	df	P
	0.05	1, 479	0.81	52.41	1, 479	< 0.01
Linear term	**			**
Quadratic term	**			**

Average (±SE) population displacement (cm/day) of infective juveniles (IJs) of Heterorhabditis bacteriophora and Steinernema carpocapsae dispersed to 2 cm wide annuli at all three distances, 3.8, 7.6 and 11.4 cm over a period of 12 to 72 hr in the presence and absence of mobile and non-mobile hosts in the microcosms containing autoclaved field soil with vegetation. Quadratic regression lines fitted for the average population displacement of IJs of each of the two species dispersed in the presence and absence of mobile and non-mobile hosts are bracketed. Double asterisk (**) indicates the significant difference in the estimated linear and quadratic coefficients between the two species, horizontally and the type of host (mobile vs non-mobile) within a species, vertically (from regression analyses, P ≤ 0.05). Analysis of variance indicates significant difference in the average population displacement of a species in the presence and absence of mobile and non-mobile hosts at P ≤ 0.05.