Bionomics of the leucaena seed beetle (Acanthoscelides macrophthalmus (Schaeffer, 1907))Coleoptera: Bruchidae)
Date Issued
2008
Date
2008
Author(s)
Wu, Li-Hsin
Abstract
Leucaena leucocephala (Lam.) de Wit is a powerful invasive weed that can cause serious ecological problems such as degrading local vegetation diversity. A newly recorded seed beetle (Acanthoscelides macrophthalmus (Schaeffer, 1907)) was found attacking the seeds of leucaena in Taiwan in 2004. For estimating the feasibility and efficiency of this leucaena seed beetle, A. macrophthalmus, as a biological control agent in Taiwan, we studied the morphology of its larvae, effect of temperature on developmental rate of each life stage and the influences of food supplements and mating on the longevity and fecundity of their adults. In addition, to reveal the risk of using leucaena seed beetle, utilization of pods in different shelters and other possible host plants surveys were conducted simultaneously in the field. Their generation time is 41.1 days at 27℃; egg and larva-pupa period were 6.6 and 34.5 days. The threshold of development was 14.1℃, while the parameter for egg period (4.1℃) was significantly lower; thermal constant was 526.3 degree days. Their developmental rate gradually increased with temperature, while maximum survival rate reached 66% at 23℃. Further morphological features and biological parameters for their life cycle were also described. In the field, leucaena seed beetle could complete their life cycle on pods that we manipulated on the ground and within canopy. Their population size fluctuated with the phenology of mature leucaena pods, though showing a time-lag effect for about a month. Leucaena seed beetle could feed on Albizzia falcataria, a new host genus in 11 legume species surveyed. Our study provides several developmental parameters of leucaena seed beetle which can help us to evaluate the feasibility for using them as a biological agent.
Subjects
Bruchidae
temperature
development
life history
host range
biological control
Type
thesis
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