Coincidence of silking time of corn, Zea mays and flight period of cotton bollworm, Helicoverpa armigera Hbn.: How does it affect follow-up abundancy of larvae on cobs and grain damage in various corn hybrids?

Dömötör, I. and Kiss, J. and Szőcs, G. (2009) Coincidence of silking time of corn, Zea mays and flight period of cotton bollworm, Helicoverpa armigera Hbn.: How does it affect follow-up abundancy of larvae on cobs and grain damage in various corn hybrids? Acta Phytopathologica et Entomologica Hungarica, 44 (2). pp. 315-326. ISSN 0238-1249

Text aphyt.44.2009.2.8.pdf Restricted to Repository staff only until 31 December 2029. Download (488kB)

Abstract

In order to investigate whether some corn (Zea mays) hybrids of various seasonal growing rates (FAO numbers) are damaged by larvae of cotton bollworm, Helicoverpa armigera (Lepidoptera, Noctuidae) in different levels, a set of field experiments was conducted at Mezőhegyes, Southeast Hungary, in course of 2003–2004. Phenological stages of corn hybrids and pattern of captures of H. armigera moths in pheromone traps were monitored in course of the season. Abundances of larvae of the next generation on developing cobs were also recorded. At harvest, the weight of grains damaged by H. armigera larvae, as well as the total weight of grains taken off from cobs were measured for each corn hybrids.At the time of peak flight in 2003, freshly hatched larvae appeared in the cobs of those hybrids which were already flowering (female flower), i.e. reached the silking stage, as in case of DK 391, DK 443 and Maraton (FAO numbers: 300, 380 and 450, respectively), while L1 larvae were found in the cobs of Maxima (FAO number: 580), only considerably later, when it reached silking stage. In 2004, however, all hybrids, including Maxima, flowered by the time of peak flight, and L1 larvae appeared on cobs of each hybrids without delay.The mean number of larvae was the highest in 2003 in DK 391 (141.5±4.5 larvae / 50 cobs), while DK 443, Maraton and Vilma did not differ significantly from each other (92.0±10.0, 88.5±3.0 and 78.8±3.4 larvae / 50 cobs, respectively). The lowest number of larvae was found in Maxima (34.0±3.0 larvae / 50 cobs). In contrast to this, the highest number of larvae were found on Maxima in 2004, differring significantly from that of DK 391, DK 391 and Maraton, these latter three hybrids housing only negligible low numbers of larvae.The mean weight of damaged grains per cob was the highest in DK 391 (3.5±0.6 gram) and lowest in Maxima (1.1±0.2 gram), differring from each other significantly, in 2003. A reverse result was obtained in 2004, when far the highest weight of damaged grains per cob was found in Maxima (112.2±0.7 gram), while pratically no damage occurred at DK 331, DK 443 and Maraton.The mean weight of all grains per cob was the highest in 2003 in Maraton (111.5±5.3 gram) and the lowest for DK 391 (79.2±4.3 gram), the difference being statistically significant. In 2004, however, no significant differences were found in this respect (values ranged from 162.9±2.8 gram to 192.4±21.0 gram).These results indicate that the abundace of H. armigera larvae on cobs and subsequent damage depends on the coincidence of silking of corn and peak capture of moths in pheromone traps, and not on features of the corn hybrid. Differences found in this study among hybrids barely reflect to the above-mentioned coincidence, therefore the level of infestation of the studied hybrids may vary by years and localities, and does not imply an inherent tolerant feature of the hybrids concerned. It is discussed that control measures should be considered to perform without delay in cases whenever such a coincidence is observed.

Actions (login required)

Edit Item