Host plants of the Heliothis/Helicoverpa complex in central Colombia

The cultivated and feral plants in the cotton-growing regions of Tolima, Colombia were sampled over 2 ½ yr for infestation by Heliothis/Helicoverpa spp. Four known species, subflexa, tergemina, virescens and zea, were found on 7 cultivated and 67 wild hosts. All 74 hosts except corn and grain sorghum were infested by H. virescens, although it was almost non-existent on its common-namesake, tobacco. H. zea was not common during the period and found on 5 cultivated and 3 feral hosts. H. subflexa was only found on 2 species of Physalis (Solanaceae), while H. tergemina was common in tobacco and found on no other host. An undescribed species of Helicoverpa was found in one field of cotton one year. Six parasites and several predators attacked the pests. The most infested wild host of H. virescens was Florida beggarweed, Desmodium tortuosum (Fabaceae). As cotton aged in a field with D. tortuosum, H. virescens oviposited more on the weed. Although Trichogramma sp. parasitized 1/4th of H. virescens eggs in cotton, it parasitized only 1% of eggs laid on D. tortuosum; glandular trichomes on the weed trapped Trichogramma adults and killed 13% of H. virescens 1st instars as well. The braconid Cardiochiles nigriceps parasitized a large proportion of H. virescens larvae in D. tortuosum. During the 3 cotton-growing seasons observed, H. virescens infestations in cotton were negatively correlated to infestations in D. tortuosum prior to the cotton-growing season, suggesting that maintenance of a population of H. virescens in wild hosts between growing seasons might offer refuge to density-dependent natural enemies.