Update MeetingJacques Cousteau Coastal Education Center

11/27/2018

Climate Change, Nuisance

Mosquito Populations, and

Coastal Marsh Resilience

Presenter: Rick Lathrop

Project Title: INVESTIGATING THE INTERCONNECTEDNESS OF CLIMATE CHANGE, NUISANCE MOSQUITO POPULATIONS, AND LONG-TERM RESILIENCE OF COASTAL SALT MARSH SYSTEMS

• Research Team• Project Lead: Richard G. Lathrop, Jr. , PhD., Department of Ecology, Evolution, and Natural Resources, Rutgers University,

• Science Lead: Michael J. Kennish, Ph.D., JC NERR, Department of Marine and Coastal Sciences, Rutgers University,

• Collaborative Lead: Lisa Auermuller, JC NERR,

• Education Coordinator: Kaitlin Gannon, JC NERR,

• Mosquito Research Lead: Dina M. Fonseca, Ph.D., Department of Entomology, Rutgers University,

• Brian Johnson, Postdoctoral Research Associate

• Mosquito Control Specialist: Scott Crans, M.S., NJDEP

• Technical Staff: Rachael Sacatelli, CRSSA, Rutgers University

• End Users/Cooperators:

• Michael Senyk and Joe Schmidt, Ocean County Mosquito Extermination Commission

• John Abdill, Jr., Atlantic County Office of Mosquito Control

• Erin Nooney, Burlington County Mosquito Control

• Victoria Thompson and Vince Poulsen, Monmouth County Mosquito Control Division

• Peter Bosak, Cape May Mosquito Control

• Martha Maxwell-Doyle, Barnegat Bay Partnership, NJ MidAtlanticCoast Wetlands Assessment(MACWA)

• Peter Winkler, NJ Division of Fish & Wildlife, Bureau of Land Management

Conceptual Model

How will a change in the location and

timing of mosquito breeding affect the

operations and planning by the

mosquito control agencies?

Based on round table discussions with the end-users, we developed 3 main objectives:

•High resolution habitat mapping/modelling to identify mosquito production hotspots under extreme flooding events;

•How restoration techniques designed to maintain marsh elevation (i.e., thin layer application) might affect mosquito production;

•Enhanced techniques for monitoring mosquito populations.

What types of information or tools do the end users need to make better decisions and/or be more effective in their work?

Identifying Salt Marsh Mosquito Population Hotspots

Develop strategies to effectively identify specific salt marsh mosquito productive hotspots.

•Soil-elevation-vegetation surveys to document marsh habitat characteristics.

• Soil cores to document presence of mosquito eggs/larvae or egg shells.

Allocation of Survey Sites

Field Survey Design

Mosquito Sampling

Each soil core was incubated

under a light:dark photoperiod

for 3 days to allow recently laid

eggs to mature or break

“diapause”, then flooded and

larvae counted.

Objective:

Delineate

species

oviposition

and relative

abundance

Summary of soil core results

No. of

Surveys

No. Soil

Cores

No. Positive

Soil Cores

# Larvae Percent

Soil Cores

Positive

All Sites 22 1929 94574

4.87

Sites with

>2

positive

soil cores

No. of

Surveys

No. Soil

Cores

No. Positive

Soil Cores

Percent

Soil Cores

Positive

3 389 87 536 22.37

2017

Summary of soil core results

No. of

SurveysNo. Soil Cores

No. Positive Soil

Cores# Larvae

Percent Soil

Cores

Positive

All Sites 21 1385 82 820 4.82

Sites with >2

positive soil

cores

No. of

SurveysNo. Soil Cores

No. Positive Soil

Cores# Larvae

Percent Soil

Cores

Positive

5 478 73 737 10.10

2018

No. of

SurveysNo. Soil Cores

No. Positive Soil

Cores

# Larvae Percent Soil

Cores

Positive

All Sites 22 1929 94574

4.87

Sites with >2

positive soil

cores

No. of

SurveysNo. Soil Cores

No. Positive Soil

Cores

Percent Soil

Cores

Positive

3 389 87

536

22.37

2017

Mosquito Abundance vs. Vegetation Composition

Thin Layer Application of Dredge Spoils

No observed

presence of breeding

mosquitoes in 2 yr

old TLD application.

Can an environmental DNA (eDNA) approach increase

sampling efficiency?

• Soil eDNA: Delineate species oviposition and relative abundance via the collection and analysis of small quantities of soil (<10g).

• Aquatic eDNA: Determine potential for nuisance by detection of larval stages even in difficult to sample/low density situations

OBJECTIVE OF DNA ANALYSIS SUBCOMPONENTS

EGG COUNTING

FROM SOIL SAMPLES

WHY? To develop a dataset of egg abundance.

QUANTITATING DNA

WITHIN SINGLE EGG

WHY? To determine how much variability exists between individual eggs. Understanding this variability will allow for a more informed estimates of egg abundance in a sample.

Paired samples collected to independently measure egg abundance to calibrate qPCR determination of egg abundance.

EGG COUNTING FROM SOIL SAMPLES

5421 3

QUANTITATING DNA / MOSQUITO EGG

FLUOROMETRIC ANALYSIS02

Avg. DNA/egg (ng/nL)

1.62

Stand.Dev.

0.33

Average DNA/egg (ng/nL)

1.67

Stand.Dev.

0.28

Meeker’s Method ‘Typical’ Hot-Shot

*HS4 in Zieritz et al. 2018 *HS3 in Zieritz et al. 2018

Both methods appear to be equally effective.

EXTRACTION01

SUMMARY OF DNA ANALYSIS SUBCOMPONENTS

EGG COUNTING

FROM SOIL SAMPLES

Finished.

QUANTITATING DNA

WITHIN SINGLE EGG

Quantitating results look promising.

Next step: statistical comparison with egg counts.

eDNA ASSAY

GENERATION

Why? To be able to identify mosquitoes down to the species level from both soil core and standing water.

In process.

● Locating site of mosquito egg laying is relatively hard

to find:

○ 3/22 sites sampled had more then 2 positive

samples in 2018;

○ 5/21 sites sampled had more then 2 positive

samples in 2017;

○ Less then 5% hit rate on the soil cores.

● Conundrum: How is ongoing management affecting

our ability to discern robust relationships between

habitat structure and mosquito breeding activity?

What Have We Learned?

Most of the marshes along the NJ coast are regularly treated with Bti.Light trapping data suggest a wholesale depression in numbers of adults.

● In 2017, Ae. sollicitans (89.79%) dominated the collections, followed by Ae. taeniorhynchus (9.64%) and Ae. cantator (0.67%).

○ What could be significant is that Ae. taeniorhynchus is a southern species that appears to be expanding its range northward.

● Common wisdom was that good breeding habitat for both species must not be flooded by more than 4 tides per month (e.g. 2 spring tides of 2 days each), which means these sites will be above the mean high water mark. This usually equates to “high marsh” dominated by Spartina patens and Distichlis spicata.

● However, in 2017, mosquitoes were observed primarily in Sp.

alterniflora, while in 2018 (when we surveyed more broadly) mosquitoes were found across all vegetation types.

● Suggesting that mosquitoes appear to be less discriminating in their breeding habitat choices than originally thought.

What Have We Learned?

Bermed areas that blocknormal high tides

Bermed areas that fill with rain water

Recent discussions with our Mosquito Agency collaborators have focused on using their local knowledge to identify microhabitat features that may serve as mosquito breeding habitat.

Questions? Comments?