What’s eating you? How predation and parasitoidism suppress populations of Lema daturaphila

Background/Question/Methods

Biological control of pests has the potential to be a useful tool in agriculture. But improper assessment of population dynamics and predator and prey interactions can prove to be detrimental in the use of this ecological application. Thus conducting appropriate research of population dynamics and what limits the population growth of a considered pest is key in utilizing biological control. A two month study on the population dynamics of the three lined potato beetle Lema daturaphila (Coleoptera:Chrysomelidae) was conducted during the summer of 2009 in the ecological field station Blandy Experimental Farm located in Boyce, Virginia. An estimated life table was constructed using proportions of mortality observed in each different life stage of the beetle. The life table was constructed with the number of egg clutches found throughout the summer on Lema daturaphila preferred host Physalis longifolia.

Results/Conclusions

The highest proportion of mortality occurred in the transition from eggs to larvae. The highest mortality factor observed in midsummer was predation, with no significant parasitoidism by the tachinid fly Myiopharus infernalis (Diptera:Tachinidae) while late summer parasitoidism proportions were observed to increase. The study suggests that egg predators play a bigger role on the population decline of Lema daturaphila during mid-summer, while parasitoidism seemed to help suppress the beetle population later in the summer. Investigating the community of predators that control the population growth of L. daturaphila will grant us a potential strategy to apply for biological control of pests such as L. daturaphila.