Porphyric Insecticides - Chlorophyll Biosynthesis and Technological Applications - page 426

Table 18.13 Effects of ALA and substituted dipyridyls, on Proto accumulation and larval
mortality in T . ni

Proto content
(nmol/100 mg protein)

Larval mortality after 6 days
in the greenhouse (%) Entry Treatment a

0.9a b 1 Control 0.0a

2 ALA 2.3a 1.7a

2,2 0 -Dipyridyl disulfide 3 1.0a 0.0a

4 Above + ALA 1.6a 0.0a

2,2 0 -Biquinoline

5 0.9a 0.0a

6 Above + ALA 2.0a 0.0a

4,4 0 -Diphenyl-2,2 0 -dipyridyl

7 1.2a 1.7a

8 Above + ALA 2.3a 1.7a

2,2 0 -Dithiobis (5-nitropyridine) 9 0.7a 0.0a

10 Above + ALA 1.8a 5.0a

2,2 0 -Dithiobis (pyridine) N-oxide 0.7a 11 0.0a

12 Above + ALA 10.46a 56.7c

4,4 0 -Dimethyl-2,2 0 -dipyridyl 13 1.9a 0.0a

14 Above + ALA 18.1a 28.3b

15 Phenyl 2-pyridyl ketoxime 1.5a 1.7a

16 Above + ALA 21.9a 33.3b

17 2,2 0 :6 0 ,2 00 -Terpyridine 6.2a 11.7a

18 Above + ALA 181.1b 98.2d

2,2 0 -Dipyridyl 19 15.0a 48.3c

20 Above + ALA 176.3b 100.0d

Correlation coefficient 0.91

Level of significance 0.1 %

Adapted from Gut et al. ( 1993 )
a Treatment consisted of control diet lacking any added ALA or modulator, diet containing 4 mM
ALA, 3 mMmodulator or 4 mM ALA + 3 mMmodulator, in a randomized complete block design
with three replicates. Percent larval death was arcsine transformed prior to statistical analysis
b Means followed by the same letter within a column are not significantly different at the 5 % level
of significance

closely associated with their ability to enhance the conversion of exogenous ALA to
Proto (Table 18.13 ). As was observed with Oph, the presence of N atoms at position
1 and 10 of the macrocycle appeared to be essential for porphyric insecticide
activity. This was evidenced by a 30 % reduction in activity in phenyl 2-pyridyl
ketoxime with a N atom at position 1 and a carbon atom at position 10 (Fig. 18.7 )as
compared to dipyridyl ketoxime with 2 N atoms at positions 1 and 10 of the
macrocycle (data not shown). The presence of a third 6-membered N heterocyclic
ring as in 2,2 0 :6 0 2 00 -terpyridine did not decrease insecticidal activity (Fig. 18.6 ,
Table 18.14 , # 17). Ring substitution at the periphery of the Dpy macrocycle,
however, had a highly negative effect on insecticidal performance. For example
the addition of phenyl, benzyl, or methyl groups as in 4,4 0 -diphenyl-Dpy,
biquinoline and 4,4 0 -dimethyl-Dpy, dramatically reduced the insecticidal activity
(Table 18.13 , # 5, 6, 7, 8, 13, 14).