Suitability of some Lantana camara varieties as host plants for the root-feeding flea beetle, Longitarsus bethae

Abstract

Compatibility between the root-feeding agent Longitarsus bethae Savini & Escalona and the varieties of the target weed Lantana camara L. could influence the chances of successful establishment and effectiveness of this agent as a biocontrol agent of lantana in South Africa. Laboratory experiments were conducted to determine the influence of major South African lantana varieties on feeding, colonization, oviposition preference and larval survival of L. bethae. Feeding preference and the number of adults per plant varied among the varieties. The most damaged and colonized varieties were 150 Orange, 009 Light Pink and 113 Dark Pink. Variety 018 Dark Pink was the least damaged, while 021 Total Pink and 029 White Pink were the least colonized. Females laid the highest number of eggs on variety 150 Orange. The lowest number of eggs was recorded on Australian Richmond Pink and the closely related species Lippia wilmsii. Larval survival differed significantly among the varieties. The highest survival was recorded on 150 Orange. Duration of development also varied significantly among the varieties, with the slowest rate of development recorded on variety 029 Light Pink and the quickest on variety 015 White Yellow. Although variations in female body size were less significant among varieties, males emerging from variety 150 Orange were slightly smaller than those emerged from other varieties. There was a significant tendency for females to select varieties that enhanced the survival of their offspring, which met the predictions of the preference-performance hypothesis. The data suggest that the chances of establishment and successful control of the weed are expected to be much greater on those varieties that were preferred for oviposition and provided better larval performance.

Keywords:

• Longitarsus bethae
• Lantana camara
• feeding
• colonization
• oviposition
• larval survival
• biological control

Acknowledgments

The author is indebted to Professor J.H. Hoffmann of the University of Cape Town and Dr A.J. Urban of Plant Protection Research Institute for valuable comments and advice on earlier drafts of this manuscript. Special thanks are extended to Mr Matlala Phenye for his technical support during the study. The project was financially supported by the Working for Water programme of the Department of Water Affairs and Forestry and Plant Protection Research Institute of the Agricultural Research Council.