Table 1.

Estimates of median lethal concentrations (LC₅₀) and relative potencies by fitting a logistic regression model to the concentration–mortality response data of fungal and virus pathogens, and their combinations against the third instar larvae of sugarcane.

Inoculum	N	df	a χ2	Slope ± SE	Intercept ± SE	b h	LC50 Observed (95% CI)	c LC50 Expected
Ma	300	28	32.41	1.54 ± 0.24 **	−11.9 ± 1.9	1.2	5.61 × 107 (3.1 × 107; 9.1 × 107)	-
Bb	300	28	39.75	1.02 ± 0.24 **	−7.3 ± 1.9	1.42	1.35 × 107 (1.86 × 106; 3.3 × 107)	-
DisaGV	300	28	23.61	1.12 ± 0.20 **	−8.4 ± 1.6	1.0	3.36 × 107 (1.4 × 107; 6.0 × 107)	-
Ma + Bb	300	28	30.12	1.04 ± 0.21 **	−7.5 ± 1.7	1.08	1.40 × 107 (3.1 × 106; 3.1 × 107)	2.17 × 107 Additive
Ma + DisaGV	300	28	29.10	0.95 ± 0.19 **	−7.0 ± 1.6	1.04	2.7 × 107 (7.7 × 106; 5.6 × 107)	4.21 × 107 Additive
Bb + DisaGV	300	28	26.30	1.32 ± 0.21 **	−10.7 ± 1.7	1.0	1.22 × 108 (7.4 × 107; 2.0 × 108)	1.92 × 107 Antagonistic
Ma + Bb + DisaGV	300	28	34.02	1.41 ± 0.24 **	−11.2 ± 1.9	1.22	8.5 × 107 (4.7 × 107; 1.5 × 108)	2.49 × 107 Antagonistic

^a Pearson χ² for the fitted logistic model (logit). ^b Heterogeneity factor for the fitted model in relation to the experimental data. ^c LC₅₀ expected and computed by the model quoted in Tabashnik (1992). ** = Significant at p < 0.01. Ma—Metarhizium anisopliae; Bb—Beauveria bassiana; DisaGV—Diatraea saccharalis granulovirus.