Pink bollworm growth

The growth-inhibitory activity of azadirachtin fed in artificial diet to three species of agricultural pests, gossypiella, H. zea, and frugiperda, was compared to the activity of a number of limonoids isolated from plants in the Meliaceae and the Rutaceae (Table VI). After azadirachtin, the most active limonoid was cedrelone (Figure 13). Cedrelone was unique among the compounds tested in Table VI since it was the only limonoid, besides azadirachtin, to cause an inhibition in ecdysis (LC50 = 150 ppm) when fed to pink bollworm larvae (54). 

Table 1. Effects of 5 phytoecdysones on growth and development of pink bollworm larvae.

Little is known about the pharmacological activity of the cathedulin alkaloids. However, Kubo et al. (49) have reisolated cathedulins E3, E4, and E5 by HPLC and report that all three compounds are potent growth inhibitors for the pink bollworm at approximately 1 ppm. This is nearly as strong as azadirachtin, one of the strongest known natural growth inhibitors. 

Development of other densification methods for certain agricultural residues is expected to lead to improvements in soil growth characteristics as well as advanced residue recovery systems for energy applications. For example, cotton is a major crop in the state of Arizona. State law requires that cotton plant residue must be buried to prevent it from serving as an overwintering site for insect pests such as the pink bollworm. Research is underway to develop two... 

A number of other llmonolds which were Isolated from plants In the Mellaceae and the Rutaceae were tested for ecdysis and growth Inhibitory activities (Table V). Cedrelone (Figure 9) was unique among the compounds tested In Table V since it was the only llmonold, besides azadlrachtln, whose toxicity (LC50 - 150 ppm) Included ecdysis Inhibition when fed to pink bollworm larvae (43). 

Homeosoma electellum) contain high concentrations of tra-chyloban-19-oic acid (70) and ( —)-16-kauren-19-oic acid (71) in their florets. As sunflower florets that contain only small amounts of these compounds are a major portion of the diet of first instar larvae of this insect, it is likely that these acids serve as feeding inhibitors. At the 1% level, both kaurenoic and trachylobanoic acids decreased the growth of sunflower moth larvae and tobacco budworm (Heliothis virescens) by about 50%. At the 0.5% level, both reduced larval growth of the cotton bollworm and the pink bollworm to less than 5% (Fig. 22.23) (Mabry and Gill, 1979). The Z-and -isomers of (- )-ozic acid (72) have been isolated from Helianthus occidentalis and may be associated with resistance to insect attack (Stipanovic et al., 1979). 

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