Author
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Lapointe, Stephen |
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Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/12/2002 Publication Date: 3/3/2003 Citation: LAPOINTE,S.L., LEGUMINOUS COVER CROPS AND THEIR INTERACTIONS WITH CITRUS AND DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE), FLORIDA ENTOMOLOGIST, 2003. Interpretive Summary: Cover crops contribute to crop productivity through erosion and weed control, biological nitrogen fixation, and by providing refuge for natural enemies of arthropod pests. A major concern to Florida citrus producers is the Diaprepes root weevil Diaprepes abbreviatus (L.). Cover crops or trap crops could contribute to citrus productivity and control of damage from D. abbreviatus. It is equally possible, however, that introduction of an additional plant resource for D. abbreviatus could result in higher pest populations. I examined the response of D. abreviatus larvae to 3 legume species: Arachis pintoi (perennial peanut), Cajanus cajan (pigeon pea) and Crotalaria pallida (rattlebox). I report here the effect of these species alone and associated with citrus on development of D. abbreviatus. Of the three legumes species studied, A. pintoi is most appropriate based on the response of D. abbreviatus and an apparent lack of competition with the citrus rootstock. When grown in close association with A. pintoi, 'Carrizo' produced the same amount of root mass as 'Carrizo' plants grown alone. The root mass of 'Carrizo' was greatly reduced when grown in association with C. cajan compared with 'Carrizo' grown alone or in association with A. pintoi. Although none of the legume species tested reduced the feeding damage caused by D. abbreviatus to 'Carrizo', larvae reared in pots with A. pintoi, associated with citrus or alone, gained weight at the same rate as larvae reared on 'Carrizo' alone. C. cajan was a superior host for development of D. abbreviatus compared with 'Carrizo' C. cajan appears to be particularly inappropriate as a cover crop because of its positive effect on larval growth. Technical Abstract: Three legume species with potential as cover crops in citrus groves were studied for their effect on the developmental biology of the Diaprepes root weevil, Diaprepes abbreviatus (L.). Larvae were reared for ~40 d in pots containing a citrus rootstock Carrizo seedling and plants of Arachis pintoi, Cajanus cajan, or Crotalaria pallida. When grown in close association with A. pintoi, Carrizo produced the same amount of root mass as Carrizo plants grown alone. The root mass of uninfested Carrizo was greatly reduced when grown in association with C. cajan compared with Carrizo grown alone or in association with A. pintoi. Although none of the 3 legume species tested reduced the feeding damage caused by D. abbreviatus to Carrizo, larvae reared in pots with A. pintoi, associated with citrus or alone, gained weight at the same rate as larvae reared on Carrizo alone. Larvae recovered from pots containing C. pallida associated with Carrizo weighed significantly more than larvae reared on Carrizo alone. C. cajan was a superior host for development of D. abbreviatus compared with Carrizo. More and larger larvae survived in pots when C. cajan was present, regardless of association with other species. C. cajan appears to be particularly inappropriate as a cover crop because of its positive effect on larval growth and reduction of citrus root mass when planted in association with citrus. Of the three legumes species studied, A. pintoi is most appropriate based on the response of D. abbreviatus and an apparent lack of competition with the citrus rootstock. |
