Helicoverpa zea subsp. larvae, Boddie, 1850
publication ID |
https://doi.org/10.1016/j.phytochem.2015.12.009 |
DOI |
https://doi.org/10.5281/zenodo.10514921 |
persistent identifier |
https://treatment.plazi.org/id/7144C772-FF8F-FFA1-FCE9-9F19FD73F875 |
treatment provided by |
Felipe |
scientific name |
Helicoverpa zea subsp. larvae |
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2.4. Effect of GHQ ( 9) on growth and development of H. zea larvae
Since gossypol ( 1) and related terpenoids are important components in the plant’s arsenal of terpenoids that protect it from herbivorous insects, it seemed appropriate to test the toxicity of GHQ ( 9) to insects. Thus, racemic gossypol ( 1) and racemic GHQ ( 9) were individually incorporated into a soybean artificial diet using the non-nutritive additive, Alphacel, at concentrations of 0.00% (control), 0.06%, 0.12% and 0.18%. To determine if GHQ ( 9) has a synergistic effect with gossypol ( 1), diets were also prepared with a total concentration of terpenoids of 0.06%, 0.12% and 0.18%, and a 15.5:84.5 ratio of GHQ ( 9):gossypol ( 1). One-day-old H. zea larvae were placed in plastic cups containing the various diets described above. After pupation, the pupae were allowed to harden for one day and then weighed. Days-to-pupation, pupal weights and percent survival to adulthood were recorded.
The mean number days-to-pupation increased as the concentration of gossypol ( 1) and GHQ ( 9) increased compared to larvae fed the control diet ( Fig. 2 View Fig ). However, the difference in days-to-pupation between the larvae fed the gossypol ( 1) and GHQ ( 9) were not significantly different. When the larvae were fed the 15.5:84.5 mixtures of GHQ ( 9) and gossypol ( 1), an extension in days-to-pupation was not observed at the 0.06% and 0.12% concentrations. However, at the 0.18% concentration, the days-to-pupation were significantly longer compared to all other diets.
The mean pupal weights ( Fig. 3 View Fig ) were significantly less for diets containing 0.12% and 0.18% gossypol ( 1), GHQ ( 9), or the 15.5:84.5 mixture of the two terpenoids compared to those fed the control diet. However, pupal weights for larvae fed gossypol ( 1) were significantly less than those fed an equivalent concentration of GHQ ( 9). No synergistic effect in reducing pupal weight was observed with the mixture.
The percent survival to adulthood of larvae fed 0.06% gossypol ( 1) or the 0.06% 15.5:84.5 GHQ ( 9):gossypol ( 1) mixture was greater than the control ( Fig. 4 View Fig ). This may be due to a hormetic effect (i.e., a biphasic dose–response exhibited by some toxic substances when fed at low concentrations) that has been demonstrated in other gossypol ( 1) feeding studies ( Stipanovic et al., 1986; Celorio-Mancera et al., 2011). Survival of larvae fed 0.06% or 0.12% GHQ ( 9) or the 15.5:84.5 mixtures were not affected. At 0.18%, gossypol ( 1) and GHQ ( 9) reduced survival with gossypol ( 1) showing mortality>50% compared to larvae fed the control diet. However, the survival to adulthood of larvae fed the 0.18% 15.5:84.5 GHQ ( 9):gossypol ( 1) diet was less than one-third those fed the control diet indicating a potential synergistic effect.
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