Ambrosia Beetle Hypothesis

Hypothesis Statement

Trees that exhibit gumming are more resistant to fusarium dieback caused by the

polyphagous shot hole borer (PSHB) because the gum secreted acts as a defense against beetles

that attempt to penetrate the bark, and as a result grant the tree faux resistance to the Fusarium

euwallaceae fungi.

Introduction

Californian agriculture is at great risk because of a disease being spread by the Polyphagous Shot

Hole Borer (PSHB), Euwallacea sp. The PSHB is an ambrosia beetle whose specific species has

been observed only in California and Israel so far [4]. Ambrosia beetles are obligate mutualistic

beetles that bore into woody trees, where they grow fungus for food [5]. Most of all known

ambrosia beetle species have
The number of adult beetles after 120 days will be counted in both the

golden-rain tree greenhouse and the avocado tree greenhouse to determine the rate of successful

reproduction. The number of newly infected trees will be quantified and rationalized to

determine the rate of infection. The same calculations should be done for the control groups to

ensure consistency. The way the PSHB will be assayed is by physically counting each insect

after euthanasia, and by measuring the lengths and depths of the galleries produced by the beetles

in the infected trees. Other symptoms of PSHB attack include small pencil-tip sized holes in tree

bark, wet spots, and frass [1]. The amount of larvae will also be counted and compared since it

has been suggested that the golden-rain tree promotes larval death through overproduction of sap

[3]. The fungal pathogen will be assayed through the physical depiction of fusarium dieback on

the tree branches, which would also indirectly confirm the presence of PSHB. To further confirm

infection from Fusarium euwallaceae, next generation sequencing will be used after successful

DNA extraction of the fungi. The sequence will be compared to the sequences obtained by