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Citation: Schurkman, J.;
Tandingan De Ley, I.; Dillman, A.R.
Lethality of Three Phasmarhabditis spp.
(P. hermaphrodita,P. californica, and
P. papillosa) to Succinea Snails.
Agriculture 2022,12, 837. https://
doi.org/10.3390/agriculture12060837
Academic Editor: Emmanouil
Roditakis
Received: 29 April 2022
Accepted: 7 June 2022
Published: 10 June 2022
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agriculture
Article
Lethality of Three Phasmarhabditis spp. (P. hermaphrodita,
P. californica, and P. papillosa) to Succinea Snails
Jacob Schurkman, Irma Tandingan De Ley and Adler R. Dillman *
Department of Nematology, University of California, Riverside, CA 92521, USA; jschu011@ucr.edu (J.S.);
itdeley@ucr.edu (I.T.D.L.)
*Correspondence: adlerd@ucr.edu
Abstract:
Succinea snails are considered to be invasive and pestiferous gastropods to those in the
floricultural industry. Their small size makes them difficult to locate within large plant shipments,
and their presence on decorative plants can constitute for an entire shipment to be rejected for sale
and distribution. Research performed on Succinea snails is limited, especially in terms of effective
mitigation strategies. The nematode Phasmarhabditis hermaphrodita is a biological control agent used
on pestiferous gastropods throughout some European nations. Here, three strains of Phasmarhabditis
from the United States (P. hermaphrodita,P. californica, and P. papillosa) were assessed as biological
control agents against Succinea snails in controlled laboratory conditions, along with the molluscicide
Sluggo Plus
®
as a control. All species of Phasmarhabditis applied at 30 IJs/cm
2
caused significant
mortality compared to the non-treated control and treatment with Sluggo Plus
®
.P. californica caused
100% mortality 6 days after exposure, while P. hermaphrodita and P. papillosa caused the same mortality
rate 7 days after exposure. The molluscicide was unable to cause significant mortality compared to
the non-treated control. Additional research with US Phasmarhabditis strains, including their non-
target effects and distribution may lead to their being a viable option for biological control against
Succinea snails.
Keywords: Phasmarhabditis; nematode; Succinea; biological control; pest management
1. Introduction
Snails and slugs belong to the class Gastropoda (Phylum: Mollusca) and are the only
gastropods who have successfully invaded and occupied a terrestrial landscape [
1
]. They
serve vital roles in multiple ecosystems where they act as detritovores decomposing plant
and animal litter which falls to the ground, while also playing a herbivorous role with live
plant matter [
2
,
3
]. While gastropods can play important roles throughout these ecosystems,
they are considered serious pests in most agricultural settings. Snail and slug pests can
cause damage to plants both above and below ground. Damage can be severe, causing
death, thinning, or wilting to the plant, and can also cause less fruit production [
4
–
6
]. In a
horticultural setting, in addition to damage inflicted to plants from gastropod pests, the
presence of slime, feces, or whole slugs significantly reduces the value to retailers. In
some cases, entire shipments can be rejected with the loss of payment to the grower due
to finding evidence of slug or snail contamination [
4
]. The economic damage caused by
terrestrial gastropods is difficult to assess due to a lack of reporting and the confusion of
symptoms of gastropod attack with other pests and vice versa. Additionally, economic
damage caused by gastropods happens to be greater when sale prices are high and a crop
is more valuable, which leads to a misleading economic assessment [4,7].
Slugs and snails can also spread a variety of diseases to a diverse set of hosts, neg-
atively affecting their sale and health. They can affect livestock by vectoring sheep and
pig lungworms in an agricultural setting where they act as intermediate hosts to the par-
asites [
8
]. They can also spread disease to humans, acting as an intermediate host and
Agriculture 2022,12, 837. https://doi.org/10.3390/agriculture12060837 https://www.mdpi.com/journal/agriculture
Agriculture 2022,12, 837 2 of 8
vector source of Angiostrongylus cantonensis (Chen, 1935) (Strongylida: Metastrongylidae),
the causative agent for rat lung worm disease [
9
]. Additionally, they are known to vector
plant pathogens such as
Alternaria brassicicola
, the causative agent for black leaf spot, and
other plant pathogenic fungi [
10
–
12
]. Furthermore, they have been suspected to have
contributed to multiple salad crop recalls due to the identification of Campylobacter spp.
and
Escherichia coli
in gastropod feces [
13
,
14
]. Business can also be affected simply by the
presence of slugs or snails. Some invasive species, such as
Theba pisana
(Müller, 1774) (Sty-
lommatophora: Helicidae) can grow to such large populations that they ruin the aesthetics
and use of an area by being present or aestevating in windows, tree trunks, sidewalks, and
various other public spaces [15,16].
One particular snail of interest is the
Succinea spp.
, also known as the amber snail.
Although visible damage on produce by
Succinea
snails has not been reported, it is never-
theless a nuisance pest, and considered one of the major gastropod pests as they are often
the most common snails found by US inspectors of plant shipments; likely due to their
small size where they may be overlooked [
17
,
18
]. The common amber snail
Succinea putris
(Linnaeus, 1758) (Stylommatophora: Succineidae) ranges from 6 to 8 mm in length, however
there are multiple species of
Succinea
snails and it is extremely difficult to morphologi-
cally identify them without genetic sequencing (http://www.molluscs.at/gastropoda/
terrestrial.html?/gastropoda/terrestrial/succineidae.html, accessed on 13 March 2022). To
date, there are three species on record in California, the latter of which was introduced [
19
]:
S. california
(Groose and Fisher 1878) (Stylommatophora: Succineidae);
S. rusticana
(Gould
1846) (Stylommatophora: Succineidae); and
S. luteola
) Gould 1848) (Stylommatophora: Suc-
cineidae). Due to the difficulty of identification, the exact range of habitat for these snails
needs further study. Previous records of these species were limited mostly to Northern
California:
S. rusticana
was found in Sonoma, San Francisco, San Benito, Kern, and San
Luis Obispo, while
S. california
was found in Monterey and San Diego. During a series of
gastropod surveys in California nurseries and garden centers,
Succinea sp.
was recorded as
one of 18 recovered species [
20
]. It was found in 5 out of 28 counties surveyed (Humboldt,
San Diego, Tulare, San Bernardino, and Stanislaus). The highest recovery was from Central
California, with 8.4% of the total collected in the area. Currently, there are 16 counties where
this snail has been detected (Table 1), and with more surveys and increased horticultural
trade, it is likely that this snail will increasingly become a threat to the industry.
Table 1. The species of Succinea found in California and the counties they were collected from.
Succinea sp. County Reference
S. california Groose and
Fisher, 1878 Monterey, San Diego [19]
S. luteola Gould 1846 * Solano [19]
S. rusticana Gould 1846
Sonoma, San Francisco, San Benito, Kern,
San Luis Obispo [19]
Succinea spp.
Orange, Sacramento, San Diego,
Riverside, San Francisco, Solano,
Los Angeles
Mc Donnell and Wilen,
unpublished data
(UCANR) **
Succinea spp. Humboldt, Stanislaus, Tulare, San
Bernardino, San Diego [20]
* Introduced species; ** https://ucanr.edu/sites/CalSnailsandSlugs/Californias_Pest_Snails_and_Slugs/Amber_
snails/ (accessed on 13 March 2022).
Several reports affirm that this snail causes damage to plants and the horticultural
trade industry on a regular basis [
21
,
22
]. Managing Succinea spp. is therefore a necessity to
prevent further losses to the industry.
A common method for mitigating gastropod pests includes the use of chemical mol-
luscicides. They have been used with varying levels of success against Succinea snails [
22
].
While chemical control methods can be effective, methods such as methiocarb and metalde-
Agriculture 2022,12, 837 3 of 8
hyde baits are non-targeted and can harm beneficial/native molluscs, fishes, earthworms,
and more [
23
,
24
]. A common molluscicide marketed as a safer alternative is Sluggo Plus
®
,
a newer formulation of iron phosphate and Spinosad (an insecticide) developed to kill
gastropods as well as some insects, e.g. earwigs, cutworms, sowbugs, and pillbugs [
25
,
26
].
This new formulation has not had a large amount of non-target testing and therefore non-
target effects are not known. However, iron phosphate has been found to decrease the
survival and growth of earthworms Lumbricus terrestris (Linnaeus, 1758) (Opisthopora:
Lumbricidae) and Eisenia fetida (Savigny, 1826) (Opisthopora: Lumbricidae) [
27
,
28
]. There-
fore, Sluggo Plus
®
is not completely safe to the ecosystem as it can have deleterious effects
on non-target earthworms.
Biological control may offer a more targeted approach to gastropod pest control which
lacks many of the issues that arise with the use of chemical molluscicides. One biological
control strategy is the use of the nematode Phasmarhabditis hermaphrodita (Schneider, 1859)
(Rhabditida: Rhabditidae). Phasmarhabditis hermaphrodita and other members of its genus
may not be as target specific as parasitoids which can target insects belonging to a specific
species or genus. However, the nematode does solely target terrestrial organisms within the
class Gastropoda. This quality makes it more target specific than commercially available
molluscicides. Phasmarhabditis hermaphrodita was discovered in Europe where it has been
commercialized under the brand name Nemaslug
®
. Although P. hermaphrodita, along with
P. californica (Tandingan De Ley et al., 2016) (Rhabditida: Rhabditidae) and P. papillosa
(Schneider, 1866) (Rhabditida: Rhabditidae) has been recovered in California [
29
–
31
] as
well as Oregon (McDonnell et al., 2018b), the nematode is not yet available commercially
and registered for use in the United States. P. hermaphrodita, as well as the other 2 species
have been found to cause significant mortality on a number of gastropod pests in laboratory
and field experimental settings [
15
,
32
–
36
]. P. hermaphrodita is also safe to most non-targets
tested with no reported detrimental impacts to the local ecosystem [
37
–
40
]. However, it
should be noted that some endemic species are susceptible to Phasmarhabditis infections,
and further non-target testing is needed before commercial application occurs in places
that the nematode has been discovered [41,42].
Data from recent surveys revealed that Phasmarhabditis species are distributed and
established throughout the entire state of California with P. californica being the most
widely distributed [
20
]. Preliminary studies also demonstrated the nematode’s biological
control potential, which was either comparable to or better than the molluscicide Sluggo
Plus
®
against the giant African land snail (Lissachatina fulica) (Férussac, 1821) (Stylom-
matophora: Achatinidae) (Mc Donnell et al., 2018a), Deroceras reticulatum (Müller, 1774)
(Stylommatophora: Agriolimacidae) [
43
] and Theba pisana in the
laboratory [15,16]
; and
D. reticulatum
in the lath house [
34
]. In the latter assays, Phasmarhabditis spp. helped to
protect ornamental Canna from further plant damage [
34
]. In this experiment, we as-
sessed the mortality of Succinea spp. after exposure to the three US strains of
P. californica
,
P. hermaphrodita
, and P. papillosa. This is the first report of the potential of
Phasmarhabditis spp.
in mitigating Succinea snails in a laboratory setting.
2. Materials and Methods
2.1. Arena Design
The arenas consisted of 350 mL, 104 cm
2
deli containers (11.5 cm diameter, 3.5 cm
height). Previous testing showed that copper was effective at thwarting snails, so the
inside walls of the arenas were covered with 3 cm wide copper tape and each were fitted
with a perforated lid to allow for air flow [
15
]. Arenas were filled with 40–45 g of soil
composed of 25% UC Mix #3 and 75% Sungro Sunshine no. 4 Mix [
44
]. Soil moisture was
then adjusted by adding about 45 mL of DI H
2
O and mixing. Arenas were kept in lab at
room temperature which ranged between 22 ◦C and 23 ◦C.
Agriculture 2022,12, 837 4 of 8
2.2. Preparation of Nematode Inocula
Phasmarhabditis infective juveniles (IJs) were collected from modified white traps [
45
]
with freshly killed Ambigolimax valentianus (Férrusac 1822) (Stylommatophora: Limacidae)
previously inoculated with mixed stages of nematodes from agar plate cultures [
15
]. All
mass-produced nematodes from the latter were grown on Nematode Growth Medium
(NGM; 1 L: 3 g NaCl, 20 g Agar, 2.5 g Peptone, 975 mL deionized H
2
O, 10 mL Uracil (2 g/L)
were added to a liter of deionized water, autoclaved, and let cool, to which 25 mL filtered
1 M KPO
4
, 1 mL filtered 1 M MgSO
4
, 1 mL 1 M CaCl
2
, and 1 mL Cholesterol (5 mg/mL)
were added. Collected IJs were stored in tissue culture flasks with water and kept in the
incubator at 17
◦
C until ready for use. The number of nematodes in each tissue culture flask
was quantified by counting the number of IJs in 10
µ
L droplets five times and taking an average
of the counts. Before applying nematodes to the arena, the desired number of nematodes per
treatment was pipetted into 10 mL falcon tubes, and the total volume was adjusted by adding
deionized (DI) H2O to standardize the volume and density of the inoculum.
All trials and replicates of lethality assays used a standardized concentration of nema-
todes based on the recommended dose for the biological control product Nemaslug
®
(BASF
Agricultural Solutions, Stockport, United Kingdom). Therefore, all tested Phasmarhabditis
species were applied at a rate of 30 IJs/cm
2
. For chemical control, the molluscicide Sluggo
Plus
®
(Monterey Lawn and Garden, Fresno, CA, USA) (0.97% iron phosphate and 0.07%
Spinosad a mixture of spinosyn A and spinosyn D) was used at the higher recommended
dose of 4.88 kg/m
2
. Non-treated control treatments consisted of arenas with snails only
without any nematodes.
2.3. Experimental Setup
Succinea snails provided by Monrovia Nursery were collected from their nurseries in
Visalia, CA, USA and shipped to UC Riverside under CDFA permit 3449. Upon delivery,
the snails were organized into 3 different groups based on size and weight. One group
composed of small snails, one of medium snails, and the last of larger snails. The mean
weights of Succinea snail used was 0.451 g while the average length was 0.78 cm (
SD = 0.247
).
Mean weights were determined by weighing all snails together and dividing the total
weight by ten. All snails were observed to be quite similar in size and weight.
Ten pre-weighed and measured snails from each organized group were introduced
onto the soil of the arena. Immediately after placing the snails in the arena, the nematode
inoculum was slowly applied to the arena using an auto pipettor. The number of dead
snails was recorded daily for one week. A toothpick method was utilized to check whether
the snails were successfully killed [
15
]. In summary, if a snail was suspected to be dead,
a toothpick was placed next to it. If the snail did not move from the toothpick after
24 h
,
then it was considered dead. All killed snails also exhibited similar symptomology in
which mixed stages of nematodes were present on the foot of the snail or inside of the
shell (Figure 1A,B). Also, snails which were dead did not respond to any stimuli when
touched or prodded with a toothpick, and exhibited zero tissue movement. They also had
a retracted or dissolved muscular foot (Figure 1A,B). The experiments were repeated three
times and each trial had a total of three replicates. Each replicate was organized by snail
size utilizing the small, medium, and large snail groups to account for size bias.
2.4. Statistical Analysis
All statistical analyses were performed with GraphPad Prism 9 (San Diego, CA, USA),
utilizing Mantel-Cox log-rank analyses to compare each treatment to each other.
Agriculture 2022,12, 837 5 of 8
Agriculture 2022, 12, x FOR PEER REVIEW 5 of 8
Figure 1. Dead Succinea snails with mixed stages of Phasmarhabditis nematodes present four days
after being exposed to the recommended dose of Phasmarhabditis (30 IJs/cm2) (A,B).
2.4. Statistical Analysis
All statistical analyses were performed with GraphPad Prism 9 (San Diego, CA,
USA), utilizing Mantel-Cox log-rank analyses to compare each treatment to each other.
3. Results
Succinea snails began to die one day after exposure (DAE) to P. papillosa at the rec-
ommended rate of 30 IJs/cm2. All other Phasmarhabditis treatments caused mortality two
DAE at the recommended rate of 30 IJs/cm2. Phasmarhabditis treatments caused signifi-
cantly higher mortality than the snail only control (p < 0.0001 for all Phasmarhabditis
treatments) and the Sluggo Plus® control (p < 0.0001 for all Phasmarhabditis treatments).
All Phasmarhabditis treatments caused 100% mortality within seven DAE; however P. cal-
ifornica was able to cause 100% mortality within the shortest amount of time, causing
100% mortality six DAE (Figure 2). All dead snails treated with Phasmarhabditis were
observed to have mixed stages of nematodes present within their shell (Figure 1). Based
on low mortality differences, Sluggo Plus® and untreated control mortality rates did not
significantly differ from each other (p = 0.340).
Figure 2. Kaplan-Meyer Graph indicating the percent survival of Succinea snails treated with the
recommended dose (30 IJs/cm2) of Phasmarhabditis papillosa (green), Phasmarhabditis californica (Red),
Phasmarhabditis hermaphrodita (Orange), the molluscicide Sluggo Plus® (Blue), or the control treat-
ment with Succinea snails only (Black), over the course of 7 days. **** indicates a p value of less than
0.0001 when compared to the control treatment.
4. Discussion
This is the first report on the mortality and susceptibility of Succinea spp. exposed to
the three United States strains of Phasmarhabditis spp. This demonstrates for the first time
Figure 1.
Dead Succinea snails with mixed stages of Phasmarhabditis nematodes present four days
after being exposed to the recommended dose of Phasmarhabditis (30 IJs/cm2) (A,B).
3. Results
Succinea snails began to die one day after exposure (DAE) to P. papillosa at the rec-
ommended rate of 30 IJs/cm
2
. All other Phasmarhabditis treatments caused mortality two
DAE at the recommended rate of 30 IJs/cm
2
.Phasmarhabditis treatments caused signif-
icantly higher mortality than the snail only control (p< 0.0001 for all Phasmarhabditis
treatments) and the Sluggo Plus
®
control (p< 0.0001 for all
Phasmarhabditis
treatments). All
Phasmarhabditis
treatments caused 100% mortality within seven DAE; however P. californica
was able to cause 100% mortality within the shortest amount of time, causing 100% mortal-
ity six DAE (Figure 2). All dead snails treated with Phasmarhabditis were observed to have
mixed stages of nematodes present within their shell (Figure 1). Based on low mortality
differences, Sluggo Plus
®
and untreated control mortality rates did not significantly differ
from each other (p= 0.340).
Agriculture 2022, 12, x FOR PEER REVIEW 5 of 8
Figure 1. Dead Succinea snails with mixed stages of Phasmarhabditis nematodes present four days
after being exposed to the recommended dose of Phasmarhabditis (30 IJs/cm2) (A,B).
2.4. Statistical Analysis
All statistical analyses were performed with GraphPad Prism 9 (San Diego, CA,
USA), utilizing Mantel-Cox log-rank analyses to compare each treatment to each other.
3. Results
Succinea snails began to die one day after exposure (DAE) to P. papillosa at the rec-
ommended rate of 30 IJs/cm2. All other Phasmarhabditis treatments caused mortality two
DAE at the recommended rate of 30 IJs/cm2. Phasmarhabditis treatments caused signifi-
cantly higher mortality than the snail only control (p < 0.0001 for all Phasmarhabditis
treatments) and the Sluggo Plus® control (p < 0.0001 for all Phasmarhabditis treatments).
All Phasmarhabditis treatments caused 100% mortality within seven DAE; however P. cal-
ifornica was able to cause 100% mortality within the shortest amount of time, causing
100% mortality six DAE (Figure 2). All dead snails treated with Phasmarhabditis were
observed to have mixed stages of nematodes present within their shell (Figure 1). Based
on low mortality differences, Sluggo Plus® and untreated control mortality rates did not
significantly differ from each other (p = 0.340).
Figure 2. Kaplan-Meyer Graph indicating the percent survival of Succinea snails treated with the
recommended dose (30 IJs/cm2) of Phasmarhabditis papillosa (green), Phasmarhabditis californica (Red),
Phasmarhabditis hermaphrodita (Orange), the molluscicide Sluggo Plus® (Blue), or the control treat-
ment with Succinea snails only (Black), over the course of 7 days. **** indicates a p value of less than
0.0001 when compared to the control treatment.
4. Discussion
This is the first report on the mortality and susceptibility of Succinea spp. exposed to
the three United States strains of Phasmarhabditis spp. This demonstrates for the first time
Figure 2.
Kaplan-Meyer Graph indicating the percent survival of Succinea snails treated with the
recommended dose (30 IJs/cm
2
) of Phasmarhabditis papillosa (green), Phasmarhabditis californica (Red),
Phasmarhabditis hermaphrodita (Orange), the molluscicide Sluggo Plus
®
(Blue), or the control treatment
with Succinea snails only (Black), over the course of 7 days. **** indicates a pvalue of less than 0.0001
when compared to the control treatment.
4. Discussion
This is the first report on the mortality and susceptibility of Succinea spp. exposed to
the three United States strains of Phasmarhabditis spp. This demonstrates for the first time
that the local strains of Phasmarhabditis can be used effectively to mitigate the presence of
Succinea. However, more research on their ecological impact and non-target effects needs
to be assessed. Due to the similarities of virulence, behavior, and genetics in European
strains and United States strains, it is likely that the US strains will have similar non-target
Agriculture 2022,12, 837 6 of 8
effects to the well tested and commercialized European P. hermaphrodita strain [
37
–
40
]. This
is especially true for the US strain of P. hermaphrodita.
Based on our results, the local strains caused 100% mortality to Succinea snails within
one week (Figure 2). Persistence of the nematodes should be further assessed to explore
how frequently treatments are necessary. The commercialized strain of
P. hermaphrodita
(Nemaslug
®
) states that the strain protects crops from pestiferous gastropods for six
weeks, indicating that the nematodes persist for the same amount of time (https://www.
nematodesdirect.co.uk/ (accessed on 18 March 2022)). It was previously found that soil
recovery of Phasmarhabditis was relatively low three weeks after application in a lath house
setting [
34
]. However, that particular aspect of the study was performed in one assay and
further experimentation is needed for that to be conclusive.
The mortality of the Succinea snails during the pathogenicity assay was comparable
to the mortality results of juvenile T. pisana being exposed to the same three strains of
Phasmarhabditis [
15
]. In both experiments, we observed near 100% mortality about one week
after exposure to Phasmarhabditis treatment. The T. pisana mortality assay observed 100%
mortality across all Phasmarhabditis treatments six DAE, while it took seven DAE to achieve
similar results with Succinea. Due to the small stature of each of these gastropods, it is
possible that the three US strains of Phasmarhabditis typically kill smaller gastropods within
a week. However, larger gastropods likely endure a longer infection period until death, as
seen with larger adult T. pisana, and the grey field slug, D. reticulatum [
16
,
34
]. Due to some
gastropods requiring time for mortality to occur upon exposure to treatment, it is possible
that the Sluggo Plus
®
treatment could have caused mortality after prolonged exposure.
Succinea snails were exposed to the molluscicide treatment for the same length of time as
those exposed to Phasmarhabditis treatment. Future experimentation with the molluscicide
may benefit from observing the mortality of the snails for a longer period of time.
Results showed that a larger number of Succinea snails in the control group died
than those exposed to the iron phosphate molluscicide Sluggo Plus®(Figure 2). However,
only a total of three additional snails died in the control group compared to the Sluggo
Plus
®
treated snails throughout the entire experiment. There were no statistical differences
between the two treatments. Ultimately, Sluggo Plus
®
was shown to be ineffective at killing
Succinea snails. It is possible that control mortality was observed due to the small size of
the snails. Some species of snails show a strong correlation between size and susceptibility
to Phasmarhabditis treatments, where smaller gastropods are killed more easily [
15
,
16
,
46
,
47
].
Susceptibility to Phasmarhabditis also seems to be species dependent as well [33,36,40].
Author Contributions:
Conceptualization, J.S. and I.T.D.L.; methodology, J.S. and I.T.D.L.; software,
J.S.; validation, J.S., I.T.D.L. and A.R.D.; formal analysis, J.S.; investigation, J.S. and I.T.D.L.; resources,
I.T.D.L. and A.R.D.; data curation, J.S.; writing—original draft preparation, J.S.; writing—review and
editing, I.T.D.L. and A.R.D.; visualization, J.S.; supervision, I.T.D.L. and A.R.D.; project administration,
I.T.D.L. and A.R.D.; funding acquisition, I.T.D.L. and A.R.D. All authors have read and agreed to the
published version of the manuscript.
Funding:
Please add: This research was funded by the United States Department of Agriculture
Specialty Crop Multi-state Program (USDA-SCMP) in partnership with the California Department of
Food and Agriculture (CDFA) (2018–2022), grant number 12509488 and also the CANERS Foundation
through California Association of Nurseries and Garden Centers (GANGC) and the Plant California
Alliance (2019–2022).
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement:
All raw datasets can be found on Mendeley Data at Jacob, Jacob; Tandin-
gan DeLey, Irma(2022), “Succinea Pathogenicity Assay”, Mendeley Data, V1, doi: 10.17632/xpbj4m4kbb.1.
Acknowledgments:
The authors thank John Keller, Vice President of Planning and Research, Mon-
rovia, for providing snail and slug specimens and valuable information on the importance of
Succinea spp. in California’s horticultural industry.
Agriculture 2022,12, 837 7 of 8
Conflicts of Interest:
Irma Tandingan De Ley declares that she is a co-inventor on a patent entitled
Mollusk-killing Biopesticide (WO2017059342A1).
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