Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/12/2001
Publication Date: 2/1/2002
Citation: Greenberg, S.M., Sappington, T.W., Setamou, M., Liu, T.X. 2002. Beet armyworm (Lepidoptera: Noctuidae) host plant preferences for oviposition. Environmental Entomology. 31(1):142-148. Interpretive Summary: Beet armyworm (BAW) attacks more than 90 plant species in at least 18 families throughout North America, many of which are crop plants. Over the last two decades, the beet armyworm has become a destructive secondary pest of cotton in the USA. In outbreaks, cotton yield losses have run up to $371 per acre. Development of efficient strategies for managing the beet armyworm will require knowledge of the biological relationships between the insect and its host plants. We determined egg-laying preferences of the beet armyworm moth and egg deposition patterns among selected crop and weed species common to the Lower Rio Grande Valley of Texas. Knowledge of hierarchies of host plant oviposition preference by BAW females will be useful in designing cultural management strategies, which may include trap cropping.
Technical Abstract: Beet armyworm, Spodoptera exigua (Hubner), oviposition preferences were determined on five host plants: cabbage (Brassica oleracea capitata L.), cotton (Gossypium hirsutum L.), bell pepper (Capsicum annuum L.), pigweed (Amaranthus retroflexus L.), and sunflower (Helianthus annuus L.) in no-choice, two-choice, and five-choice tests. Tests were conducted in the laboratory, greenhouse, and field cages. Oviposition preferences were compared on the basis of two measurements, the proportion of eggs laid on the plants to total that were deposited, and the oviposition preference index defined as [(number of eggs laid on the plant) - (number of eggs laid on the cage)] * 100 / total number of eggs laid. The proportion of eggs laid on the plants to total that were deposited was highest for pigweed and lowest for cabbage in all tests. Beet armyworm females were significantly deterred from laying eggs on cabbage and sunflower, while pigweed and cotton elicited a positive oviposition preference. Pepper tended to be neutral or slightly unattractive. Apparent interactions among plant species in choice tests produced measurable shifts in oviposition preference. Most notably, female response to pepper was enhanced in the presence of cotton or pigweed. Egg masses laid on the plants contained significantly higher numbers of eggs than those laid on the surface of the cage, except in the case of cabbage leaves. Knowledge of hierarchies of host plant oviposition preference by beet armyworm females will be useful in understanding the population dynamics of this important agricultural pest, and for developing effective monitoring and management strategies.