COULD THE NEOGREGARINE Apicystis bombi BECOME A THREAT TO HONEY BEES?

Plischuk S., M. Haramboure & C. E. Lange

Center for Parasitological Studies and VectorsCEPAVECIC – CONICET CCT La Plata – La Plata National UniversityLa Plata, Argentina

What is a gregarine?

• Eukaryotic unicelular organism that belongs to phylum Apicomplexa• Pathogen of invertebrates• 1500-2000 species. Divided in three orders (Archigregarines, Eugregarines,

& Neogregarines) that differ in morphology, habitat, host range, and life cycle.

Other eukariotic unicelular organisms associated to A. mellifera(but not gregarines)

• Microsporidia (Nosema apis; Nosema ceranae; Nosema neumanni)• Trypanosomatids (Crithidia mellificae; Lotmaria passim)• Amoebae (Malpighamoeba mellificae)

Known gregarines in A. mellifera

Eugregarines Neogregarines

Monoica apis

Apigregarina stammeri

Acuta rousseaui

Leidyana apis

Non identified species

Hitchcock, 1948

Stejskal, 1955 - 1967

Mattesia bombi(described as a pathogen of bumble bees)

Liu et al., 1974

Known gregarines in A. mellifera

Eugregarines Neogregarines

Monoica apis

Apigregarina stammeri

Acuta rousseaui

Leidyana apis

Non identified species

Hitchcock, 1948

Stejskal, 1955 - 1967

Apicystis bombi

Lipa & Triggiani, 1996

• Navicular oocysts, highly refractive in mature stage, four sporozoites each.

• Mean size: 18.9 µ x 5.6 µ.

• Target tissue: Adipose

• Effects at individual level:• Disruption/reduction of adipose tissue.• Increased sucrose sensitivity.

• Effects at colony level:• Reduced success in colony establishment.• Increased mortality rate of workers.

• Both life cycle and transmission ways are not properly known.

Apicystis bombi (Protista: Apicomplexa: Lipotrophidae)

Mature oocysts of A. bombi

Sporozoite emerging from an oocyst

From studies on bumble bees

• Known distribution and host range

• Detection techniques

• The case of southern South America

• Discussion

Main topics

Published records of A. bombiIn Bombus spp. (~20 spp.)In A. mellifera

Known distribution and host range

Plischuk et al., 2011

Morimoto et al., 2013

Lipa & Triggiani, 1996

Menail et al., 2016

Cepero et al., 2014

In other hosts

Maharramov et al., 2013

Detection techniques

• Microscopic identification

•By dissection •By homogenization

•PCM

• Molecular identification (Meeus et al., 2010)

• Using non A. bombi-specific primers

• Using A. bombi-specific primers

IGR ITS

ca. 1750 bp

18S

NeoF NeoR

IGR ITS

ca. 1750 bp

18S

ApBF1 ApUR2ca. 970 bp

ApUF2 ApUR2ca. 1600 bp

ca. 260 bp

The case of southern South America

B. ruderatus (1982)

B. terrestris (1998) Belgium

Chile

New Zealand

Israel

Survey period: 2008 – 2016

Sampling with nets (alive bees)

Storing at -32 °C

Host identification

Dissection - Homogenation

Detection by Phase Contrast Microscopy

Confirmation by molecular techniques

NW Patagonia

A. mellifera

B. terrestris

Absence of detectionsof infected A. mellifera

in other Argentineregions

B. pauloensis

Detection of B. terrestris in Argentina (2006)

Detection of A. bombi in Argentina (2008)

Chile

Argentina

Uruguay

Brazil

Bariloche

Season 2008 – 2009 2009 - 2010 2010 - 2011 2014 - 2015 2015 - 2016

n 111 107 269 162 166

Apicystis bombi 3.6% 12.1% 14.0% 11.1% 1.2%

Season 2008 – 2009 2009 - 2010 2010 - 2011 2014 - 2015 2015 – 2016

n 79 59 155 93 133

Apicystis bombi 7.6% 13.6% 3.9% 17.2% 14.3%

Season 2008 – 2009 2009 - 2010 2010 - 2011 2014 - 2015 2015 - 2016

n 111 107 269 162 166

Apicystis bombi 3.6% 12.1% 14.0% 11.1% 1.2%

Season 2008 – 2009 2009 - 2010 2010 - 2011 2014 - 2015 2015 – 2016

n 79 59 155 93 133

Apicystis bombi 7.6% 13.6% 3.9% 17.2% 14.3%

Prevalence of Apicystis bombi (%) in North Western Patagonia, Argentina

Low prevalence

Constant presence

%

seasons

Observed oocysts

A. melliferaB. terrestris

Inmature / non-viable oocysts

More than 99% did notshow refractiveness

COULD THE NEOGREGARINE Apicystis bombi BECOME A THREAT TO HONEY BEES?

Enzootic stage

Lowprevalence

Constantpresence

Inmature / non-viable

oocysts

Absence of infectedA. mellifera in other

regions

Apis mellifera wouldbe a sub-optimalhost of Apicystis

bombi

Pathogenesisat individual

level

A. bombi wouldbecome a local threat

only in areas withinfected bumble bees

High dispersal rate

of Bombusterrestris

Hypotesis

Low damage

Apicystis bombiin Apis mellifera

The case of southern South

America

2006 - Detection in Argentina

(Torretta et al.)

2007

2011

2015

Estimated spread of B. terrestrisin Argentina (2006 – 2017)

2017

Pampas

2018?

2,100 Km

Unsolved questions

• Is A. bombi able to complete its life cycle in A. mellifera? How virulent is it?

– Experimental infections

• If A. bombi indeed has arrived with alien species from Europe, how is it present in northern Argentina, Brazil, and Colombia? Does it has other unknown hosts?

– Expand collection surveys

– Haplotype-focused studies

Creation of SoLatInA (2016)

Sociedad Latinoamericana de Investigación en Abejas

Latin American Bee Research Society

Dr. Karina AntúnezPresident

kantunez03@gmail.com

Colonia, Uruguay (2016)

ThanksGracias

ObrigadoDanke

Grazie TackMerci

...and special thanks to J. Pettis, M. P. Chauzat, and M. J. F. Brown.

Hvala

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