Assessing the toxicity of selected pesticides to Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) pupae as a first step in the development of a potential novel deployment programme

Figures & data

Table 1. Treatments (products and concentrations).

Type	Treatment	Trade name	Chemical class^a	Concentration^b	Field rate (g ai ha^−1)^c
Control	Water		–	–	–
	Air		–	–	–
Adjuvant	Ammonium sulfate	AMS	–	17.97 g l^−1	1681.2
	Crop oil concentrate	COC	–	0.5% v v^−1	–
			–	1.0% v v^−1	–
	Methylated seed oil	MSO	–	0.5% v v^−1	–
			–	1.0% v v^−1	–
	Non-ionic surfactant	NIS	–	0.5% v v^−1	–
	Urea-ammonium nitrate	UAN	–	2.5% v v^−1	–
			–	5.0% v v^−1	–
Hebicide	Quizalofop	Assure II	1	0.21 g l^−1	19.3
	Bentazon	Basagran	6	3.59 g l^−1	336.3
				11.98 g l^−1	1120.9
	Glacial acetic acid	GAA	NA	104.57 g l^−1	9781.6
				209.17 g l^−1	19565.7
	Imazethapyr	Pursuit	2	0.28 g l^−1	26.3
				0.56 g l^−1	52.5
	Imazamox	Raptor	2	0.19 g l^−1	17.5
				0.37 g l^−1	35.0
	Fomesafen	Reflex	14	1.5 g l^−1	140.1
				4.5 g l^−1	420.9
	Glyphosate	Round up Powermax	9	5.66 g l^−1	529.8
				16.50 g l^−1	1543.4
	Clethodim	Select Maxx	1	0.41 g l^−1	38.2
Fungicide	Copper hydroxide	Kocide 3000	M1	7.2 g l^−1	673.6
				50.41 g l^−1	4715.1
	Flutriafol	Topguard	3	0.34 g l^−1	31.9
				1.36 g l^−1	127.5
	Penthiopyrad	Vertisan	7	0.78 g l^−1	73.1
Insecticide	K Salt of fatty acid	Safer		1.99% v v^−1	–

^a Mode of action #s.

^b Concentrations are based upon maximum and minimum one would reasonable see in the field.

^c Assuming a carrier volume of 15.3 l ha⁻¹ (10 gal ac⁻¹)^60,61.

Table 2. Parameter estimates and S.E.s for the effect of exposure time on the mortality of T. ostriniae exposed to various adjuvants, herbicides, and fungicides.

Herbicide	Conc.	Run^a	b (S.E.)^b	C (S.E.)	d (S.E.)	LT50 (S.E.)^c
Three-parameter Weibull (Type II)
Glacial acetic acid	104.57 g 1^−1	3	−0.7 (0.3)*	–	73.4 (47.9)	2.7 (4.8)
		4	−1.3 (0.4)*	–	45.5 (4.5)*	6.5 (1.2)*
Imazamox	0.37 g l^−1	2	−0.6 (0.4)	–	87.0 (6.4)*	37.4 (18.2)*
		5	−0.7 (0.3)*	–	89.8 (4.0)*	35.4 (14.5)*
Four-parameter Weibull (Type II)
Non-ionic surfactant	0.5% v v^−1	2	−10.2 (81.0)	62.0 (2.9)*	96.1 (502.2)	1.5 (3.6)
		5	−2.3 (2.7)	54.2 (15.4)*	90.9 (5.3)*	7.2 (2.1)*
Clethodim	0.41 g 1^−1	3	−16.9 (155.9)	0.0 (1.2)	12.5 (1.5)*	5.3 (6.4)
		4	−17.9 (200.5)	0.41 (1.2)	5.0 (1.5)*	5.5 (5.5)
Two-parameter exponential decay^d
Quizalofop	0.21 g 1^−1	2	–	100 (–)	–	0.8 (0.1)*
		3	–	100 (–)	–	1.1 (0.1)*
Three-parameter exponential decay
Copper hydroxide	7.2 g 1^−1	2	–	62.8 (3.8)	89.5 (39.5)	1.7 (1.7)
		3	–	27.1 (6.2)	78.6 (30.8)	2.9 (2.8)

*P-value ≤ 0.05.

^a Two separate experimental runs; each run used a different T. ostriniae cohort.

^b Abbreviations – Model lacks particular parameter; b slope at LT₅₀; c lower asymptote; d upper asymptote.

^c Hours.

^d c fixed at 100.

Figure 1. Effect of herbicides on T. ostriniae survival.

Figure 2. Effect of fungicides/bactericides on T. ostriniae survival.

Figure 3. Effect of adjuvants on T. ostriniae survival.

Table 3. Cost (USD 100 ha⁻¹) comparisons of release methods with a labour cost of $9.80 hr⁻¹ taking into account increased mortality in broadcast treatments.

	Anon., 1974 as by Jones et al., 1977	Greenberg et al., 1990	Bigler, 1986	Birthal et al., 2000	Dionne et al., 2018	Greenberg et al., 1990	Dionne et al., 2018	Filippov, 1989	Current study^d
Points ha^−1	NS^c	100	50	NS	50	∞	∞	∞	∞
Boom width (m)	–	–	–	–	–	NS	6.7	NS	12
Time (h)	80	58.3	50	1692	88.02	11.33	51.3	5.51	10.39
Labour cost (USD)	784	571.67	490	16,581.6	862.56	111.07	502.74	54.06	101.82
Total cost 0%^a^b	2.8	2.6	2.5	18.6	8.8	2.1	2.5	2.1	2.1
Total cost 10%^b	–	–	–	–	–	2.3	2.7	2.3	2.3
Total cost 20%^b	–	–	–	–	–	2.6	3.0	2.6	2.6
Total cost 30%^b	–	–	–	–	–	2.7	3.1	2.6	2.7
Total cost 40%^b	–	–	–	–	–	3.4	3.8	3.4	3.4
Total cost 50%^b	–	–	–	–	–	4.1	4.5	4.1	4.1
Total cost 60%^b	–	–	–	–	–	5.1	5.5	5.1	5.1
Total cost70%^b	–	–	–	–	–	6.8	7.2	6.7	6.8

^a Assumes a release rate of 100 000 ha⁻¹ at $20.00.

^b Total cost (in thousands) cost for extra Trichogramma to compensate for various mortalities is as follows: 10% $22.22 20% – $25; 30% – $25.57; 40% − 33.33; %50 – $40; %60 – $50%70 – $66.67%80 – $100%90 – $200.

^c NS not specified.

^d Hypothectial tractor calculated from UNL crop budgets.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, JDB, upon reasonable request.