Spatial synchrony of the two-year cycle budworm outbreaks in central British Columbia, Canada

Outbreaks of forest defoliating insects are usually synchronized over a large spatial scale. Observed records of past outbreaks are usually short and incomplete, therefore long proxy data are useful for better understanding of the spatial synchrony. In this study, we developed tree-ring proxy records of two-year cycle spruce budworm ( Choristoneura biennis Freeman) outbreaks in central British Columbia, Canada, and examined the spatial patterns of past outbreaks. This budworm is a major defoliating insect of the interior spruce ( Picea engelmannii Parry× P. glauca Moench) and subalpine fir ( Abies lasiocarpa [Hook.] Nutt.) forests in the Prince George Region of British Columbia. Four outbreaks occurred in relatively close synchrony over the entire region in the period 1880–1999, however, the initiation year, the intensity and extent of outbreaks varied spatially and from one outbreak to another. In some instances, the occurrence of outbreaks was restricted to only one area. The general synchrony of outbreaks suggested that a large-scale extrinsic factor, such as weather, was at play. However, the imperfect synchrony of outbreaks suggested that local stand characteristics, such as canopy structure, composition of tree species and host plant quality, probably played a major role in preconditioning outbreaks. Dispersal might play a role in synchronizing outbreaks, but the extent to which it contributed to the synchrony was limited in this mountainous region.     

Analysis of cell-cycle gene expression in Saccharomyces cerevisiae using microarrays and multiple synchronization methods

Microarray analysis of gene expression during the yeast division cycle has led to the proposal that a significant number of genes in Saccharomyces cerevisiae are expressed in a cell-cycle-specific manner. Four different methods of synchronization were used for cell-cycle analysis. Randomized data exhibit periodic patterns of lesser strength than the experimental data. Thus the cyclicities in the expression measurements in the four experiments presented do not arise from chance fluctuations or noise in the data. However, when the degree of cyclicity for genes in different experiments are compared, a large degree of non-reproducibility is found. Re-examining the phase timing of peak expression, we find that three of the experiments (those using α-factor, CDC28 and CDC15 synchronization) show consistent patterns of phasing, but the elutriation synchrony results demonstrate a different pattern from the other arrest-release synchronization methods. Specific genes can show a wide range of cyclical behavior between different experiments; a gene with high cyclicity in one experiment can show essentially no cyclicity in another experiment. The elutriation experiment, possibly being the least perturbing of the four synchronization methods, may give the most accurate characterization of the state of gene expression during the normal, unperturbed cell cycle. Under this alternative explanation, the observed cyclicities in the other three experiments are a stress response to synchronization, and may not reproduce in unperturbed cells.     

Causes of cyclicity of Epirrita autumnata (Lepidoptera, Geometridae): grandiose theory and tedious practice

Creating multiyear cycles in population density demands, in traditional models, causal factors that operate on local populations in a density-dependent way with time lags. However, cycles of the geometrid Epirrita autumnata in northern Europe may be regional, not local; i.e., successive outbreaks occur in different localities. We review possible causes of cycles of E. autumnata under both local and regional scenarios, including large-scale synchrony. Assuming cyclicity is a local phenomenon, individual populations of E. autumnata display peaks but populations all over the outbreak range fluctuate in synchrony. This concept assumes that the peaks at most localities are so low that they do not lead to visible defoliation and easily remain unnoticed. In this scenario, populations are able to start recovery a few years after the crash, i.e., at the time of the mitigation of detrimental delayed density-dependent factors, such as delayed inducible resistance of the host plant or parasitism. In that case, the same factors that lead to crashes also explain the periodicity of cyclic fluctuations. According to the regional cyclicity scenario, different factors can be important in different phases of the cycle. The key is to identify the factors that tend to produce outbreaks with a periodicity of about 10 years. Initiation of the increase phase seems to coincide with maxima in sunspot activity, but causal connections remain unclear. Climatic factor(s) associated with the solar cycle could contribute to the large-scale geographic synchrony.     

森林害虫发生的空间模式研究进展

森林昆虫种群表现出多样的时空模式,空间同步性是其中最常见的。回顾了森林昆虫空间同步性的特点、形成机制及研究方法方面的进展。森林害虫发生的同步性是广泛存在的,但不同昆虫种类的同步性大小不同。空间同步性常随距离的增大而下降,还与时间尺度有关。Moran效应和扩散是解释空间同步性的两种主要机制,通常Moran效应的影响要比扩散大。从虫害发生数据的获取、同步性的度量及成因3个方面介绍了空间同步性的研究方法方面的进展。利用树轮生态学原理重建森林虫害发生历史的方法可在事后获取可靠的数据,很值得国内研究者借鉴和应用。在空间自相关度量上,空间统计学方法和地统计学方法都是非常有力的手段,但由于不能处理多时间点数据而限制了其在同步性研究中的应用。在同步性成因研究中,利用变异分解将基于距离的Moran特征向量图(dbMEM)作为空间变量研究害虫发生的驱动力是比较新颖的研究方法。     

Geographical and temporal patterns of lemming population dynamics in Fennoscandia

There is a long-lasting debate in ecology on cyclicity. synchrony and time lags of lemming population fluetuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4-yr cycles. There was no support for the hypothesis of a north-south gradient in cycle length. However, we found periods of prolonged interruptions in the cyclicity, which were more eommon in northern areas. We found a high degree of synchrony between regions, with only a weak relationship to distance. The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate, than intrinsic factors, such as dispersal.     

Population fluctuations of the wood lemming<Emphasis Type="Italic">Myopus schisticolor</Emphasis> in eastern and western Finland

Olavi Eskelinen, Pertti Sulkava and Risto Sulkava From 1982 to 2003 we studied fluctuations in populations of the wood lemmingMyopus schisticolor (Liljeborg, 1844) in the Heinävesi (eastern Finland) and Keuruu regions (western Finland) by counting field signs and dead animals in standardized field surveys. We compared the population fluctuations of lemmings to those of other voles, owls and small mustelids in these regions. The lemming population in Heinävesi fluctuated regularly in 3-year cycles and in synchrony with the field vole population. Populations of owls also fluctuated in synchrony with wood lemming and field vole populations. In the Keuruu region, oscillations in the wood lemming population were irregular, and neither lemming and vole populations nor lemming and owl populations were correlated. Although direct mechanistic evidence is lacking, specialist predators such as weasels and owls probably cause the cyclicity in the field vole and wood lemming populations in the Heinävesi area. On the other hand, scarcity of high-quality habitats, unfavourable winter weather conditions and generalist predators may prevent the development of cyclicity in the wood lemming population of Keuruu.     

Geographic variation in forest composition and precipitation predict the synchrony of forest insect outbreaks

Evaluating the causes of spatial synchrony in population dynamics in nature is notoriously difficult due to a lack of data and appropriate statistical methods. Here, we use a recently developed method, a multivariate extension of the local indicators of spatial autocorrelation statistic, to map geographic variation in the synchrony of gypsy moth outbreaks. Regression analyses indicated that local synchrony of gypsy moth defoliation increased with the local synchrony of precipitation and the proportion of host tree density composed of oaks, especially those in the Lobatae (red oak) section. This may be the first study that demonstrates a relationship between defoliator population synchrony and host tree composition. More broadly, this study contributes to a small body of recent work that illustrates how mapping hotspots of unusually high or low synchrony facilitates an improved understanding of factors influencing spatially synchronous population dynamics generally, and triggers of pest insect outbreaks, more specifically.     

Synchrony, scale and temporal dynamics of rock partridge (Alectoris graeca saxatilis) populations in the Dolomites

1. Harvesting records of rock partridge ( Alectoris graeca saxatilis ) were examined first to identify the presence of cycles in a species with a southern European distribution and then to examine synchrony between populations at a range of scales.
2. Hunting records from 1965 to 1994 were obtained from 210 hunting areas and analysed at three spatial scales: subpopulation, population and metapopulation. Rock partridge exhibited cyclic fluctuations in about 40% of the time series with a period of 4–7 years. The results did not change with spatial scale. The density-dependent structure of the populations showed that most populations exhibited damped oscillations.
3. The proportion of populations that were in synchrony increased with scale from the population to metapopulation level. There was no decline in synchrony with distance but a large variation between populations irrespective of distance.
4. The populations clustered into dry and wet habitats, with those in the dry habitat being more cyclic. We suggest the lack of spatial synchrony with distance but greater synchrony within habitats may reflect the influence of stochastic events operating on populations with different density dependence structures.     

A comparison of methods for estimating common vole (Microtus arvalis) abundance in agricultural habitats

Rodent outbreaks cause significant crop damages in agricultural areas worldwide, but routinely monitoring large areas at low cost remains a challenge. The common vole Microtus arvalis has recently colonized the agricultural plains of the northern Iberian Plateau, an area where it has started to produce population outbreaks with important impacts in agriculture, the environment and human health. Vole monitoring has become of prime importance to implement preventive management measures to control populations. In order to find a simple and reliable vole monitoring method to be applied in large areas, we compared abundance estimates derived from three methods: capture–mark–recapture (CMR), single capture events (SCE) and presence/absence of vole activity signs (VAS) during three seasons and on the main agricultural habitats in the study area. We show that an activity index based on the presence of fresh droppings and/or clippings had a similar performance to SCE in a large sample of plots (n = 222) across habitats and seasons. Data obtained with both methods (SCE, VAS) were also well correlated with those obtained with CMR, despite a limited sample size (n = 23 CMR plots). We suggest that the VAS method, which is a cheaper and easier alternative to trapping methods, provides a promising tool for scientists and managers to implement large scale monitoring of common vole in agricultural areas.     

Presence of males affects the incidence of ovulation after pouch young removal in brushtail possums (Trichosurus vulpecula)

The traditional method for inducing and synchronising oestrus in the brushtail possum (Trichosurus vulpecula) is by removal of their suckling pouch young (RPY). However, our studies have recently shown that, in addition to wide variation between animals in the time of ovulation after RPY, a proportion of animals failed to ovulate. Evidence from several mammalian species indicates that the presence of males can stimulate ovarian activity and synchronise oestrus in females. The aim of this study was to determine the effect of the male on the oestrous cycle of the female brushtail possum after RPY. A total of 67 adult female brushtail possums were treated as three replicates. In order to observe the day of preovulatory follicle emergence and ovulation, animals underwent laparoscopic examination at 1–4 day intervals over a period from 0–21 days after RPY. The first replicate (N=18, May/June 1995) involved only animals kept in isolation from males, whereas the two remaining replicates compared ovarian responses between animals kept with (N=10, July 1995; N=14, June 1996) or in isolation from (N=10, July 1995; N=15, June 1996) males. The incidence of ovulation after RPY was significantly higher in females that were housed with males than in those kept in isolation from males (100%, 92.8% vs. 50.0%, 66.7%, 14.3%; P<0.001). Every animal that ovulated, had previously had a preovulatory follicle present at the site where the corpus luteum formed. Conversely, none of the animals that failed to ovulate, developed a preovulatory follicle during the period of study. The range of mean day of preovulatory follicle emergence (6.00–6.86 days), of ovulation (11.80–12.20 days) and the synchrony of ovulation between animals (range 8–17 days) after RPY, were not significantly affected by the presence of males. This study demonstrates for the first time, that the presence of males significantly increases the incidence of ovulation after RPY in the brushtail possum. However neither the timing of reproductive events nor the synchrony of ovulation were affected by presence of the male.     

The impact of National Death Index linkages on population-based cancer survival rates in the United States

Background: In order to ensure accurate survival estimates, population-based cancer registries must ascertain all, or nearly all, patients diagnosed with cancer in their catchment area, and obtain complete follow-up information on all deaths that occurred among registered cancer patients. In the US, linkage with state death records may not be sufficient to ascertain all deaths. Since 1979, all state vital statistics offices have reported their death certificate information to the National Death Index (NDI). Objective: This study was designed to measure the impact of linkage with the NDI on population-based relative and cancer cause-specific survival rates in the US. Methods: Central cancer registry records for patients diagnosed 1993–1995 from California, Colorado, and Idaho were linked with death certificate information (deaths 1993–2004) from their individual state vital statistics offices and with the NDI. Two databases were created: one contained incident records with deceased patients linked only to state death records and the second database contained incident records with deceased patients linked to both state death records and the NDI. Survival estimates and 95% confidence intervals from each database were compared by state and primary site category. Results: At 60 months follow-up, 42.1–48.1% of incident records linked with state death records and an additional 0.7–3.4% of records linked with the NDI. Survival point estimates from the analysis without NDI were not contained within the corresponding 95% CIs from the NDI augmented analysis for all sites combined and colorectal, pancreas, lung and bronchus, breast, prostate, non-Hodgkin lymphoma, and Kaposi sarcoma cases in all 3 states using relative survival methods. Additional combinations of state and primary site had significant survival estimate differences, which differed by method (relative versus cause-specific survival). Conclusion: To ensure accurate population-based cancer survival rates, linkage with the National Death Index to ascertain out of state and late registered deaths is a necessary process for US central cancer registries.     

Synchrony and geographical variation of the spruce bark beetle (<Emphasis Type="Italic">Ips typographus</Emphasis>) during a non-epidemic period

Spatio-temporal analyses of non-epidemic bark beetle populations may provide insight in dynamics predisposing for outbreaks. The present article presents a spatio-temporal analysis of the population dynamics of Ips typographus based on pheromone trap data from southeast and mid-Norway in the post-epidemic period 1979–2002. The analyses include regression analyses, hierarchical cluster analysis, and analysis of spatial synchrony of beetle time series and climatic data by means of nonparametric spatial covariance functions. The mean abundance of beetles declined linearly with latitude. In addition, the time series means were higher in areas with high forest productivity and rocky soils predisposed to drought. The time series patterns differed significantly between northern and southern study areas. The regional synchrony of the time series was fairly high (0.38), indicating that some large-scale climatic factor may influence the dynamics. Windfelling was the external variable showing the most parallel pattern of correlation to the beetle dynamics. We thus posit that large windfall events may be a major instigator and synchronizer of beetle outbreaks in areas subjected to regionalized weather systems.     

Let’s Dance Together: Synchrony,Shared Intentionality and Cooperation

Previous research has shown that the matching of rhythmic behaviour between individuals (synchrony) increases cooperation. Such synchrony is most noticeable in music, dance and collective rituals. As well as the matching of behaviour, such collective performances typically involve shared intentionality: performers actively collaborate to produce joint actions. Over three experiments we examined the importance of shared intentionality in promoting cooperation from group synchrony. Experiment 1 compared a condition in which group synchrony was produced through shared intentionality to conditions in which synchrony or asynchrony were created as a by-product of hearing the same or different rhythmic beats. We found that synchrony combined with shared intentionality produced the greatest level of cooperation. To examinef the importance of synchrony when shared intentionality is present, Experiment 2 compared a condition in which participants deliberately worked together to produce synchrony with a condition in which participants deliberately worked together to produce asynchrony. We found that synchrony combined with shared intentionality produced the greatest level of cooperation. Experiment 3 manipulated both the presence of synchrony and shared intentionality and found significantly greater cooperation with synchrony and shared intentionality combined. Path analysis supported a reinforcement of cooperation model according to which perceiving synchrony when there is a shared goal to produce synchrony provides immediate feedback for successful cooperation so reinforcing the group’s cooperative tendencies. The reinforcement of cooperation model helps to explain the evolutionary conservation of traditional music and dance performances, and furthermore suggests that the collectivist values of such cultures may be an essential part of the mechanisms by which synchrony galvanises cooperative behaviours.     

Geographical variation in the spatial synchrony of a forest-defoliating insect: isolation of environmental and spatial drivers

Despite the pervasiveness of spatial synchrony of population fluctuations in virtually every taxon, it remains difficult to disentangle its underlying mechanisms, such as environmental perturbations and dispersal. We used multiple regression of distance matrices (MRMs) to statistically partition the importance of several factors potentially synchronizing the dynamics of the gypsy moth, an invasive species in North America, exhibiting outbreaks that are partially synchronized over long distances (approx. 900 km). The factors considered in the MRM were synchrony in weather conditions, spatial proximity and forest-type similarity. We found that the most likely driver of outbreak synchrony is synchronous precipitation. Proximity played no apparent role in influencing outbreak synchrony after accounting for precipitation, suggesting dispersal does not drive outbreak synchrony. Because a previous modelling study indicated weather might indirectly synchronize outbreaks through synchronization of oak masting and generalist predators that feed upon acorns, we also examined the influence of weather and proximity on synchrony of acorn production. As we found for outbreak synchrony, synchrony in oak masting increased with synchrony in precipitation, though it also increased with proximity. We conclude that precipitation could synchronize gypsy moth populations directly, as in a Moran effect, or indirectly, through effects on oak masting, generalist predators or diseases.     

Elevational gradient in the cyclicity of a forest-defoliating insect

Observed changes in the cyclicity of herbivore populations along latitudinal gradients and the hypothesis that shifts in the importance of generalist versus specialist predators explain such gradients has long been a matter of intense interest. In contrast, elevational gradients in population cyclicity are largely unexplored. We quantified the cyclicity of gypsy moth populations along an elevational gradient by applying wavelet analysis to spatially referenced 31-year records (1975–2005) of defoliation. Based on geographically weighted regression and nonlinear regression, we found either a hump-shaped or plateauing relationship between elevation and the cyclicity of gypsy moth populations and a positive relationship between cyclicity and the density of the gypsy moth’s preferred host-tree species. The potential effects of elevational gradients in the density of generalist predators and preferred host-tree species on the cyclicity of gypsy moth populations were evaluated with mechanistic simulation models. The models suggested that an elevational gradient in the densities of preferred host tree species could partially explain elevational patterns of gypsy moth cyclicity. Results from a model assuming a type-III functional response of generalist predators to changes in gypsy moth density were inconsistent with the observed elevational gradient in gypsy moth cyclicity. However, a model with a more realistic type-II functional response gave results roughly consistent with the empirical findings. In contrast to classical studies on the effects of generalist predators on prey population cycles, our model with a type-II functional response predicts a unimodal relationship between generalist-predator density and the cyclicity of gypsy moth populations.     

El Niño-Southern Oscillation modulates insect outbreaks in humid subtropical China: Evidences from tree rings and carbon isotopes

Insect outbreaks are key disturbances triggering decline episodes in humid subtropical evergreen forests in eastern China. However, their long-term variability and linkages to climate are still unclear largely due to the shortness of records reporting forest damage. A retrospective approach would improve our understanding of long-term outbreak variability and its dependence on climate and relevant atmospheric circulation patterns such as the El Niño-Southern Oscillation (ENSO). This study provides a dendrochronological reconstruction of Dendrolimus punctatus outbreaks affecting Pinus massoniana in humid subtropical eastern China. We used tree-ring width and carbon isotope data from sites where outbreaks were or not were reported for the past fifty years, here considered as host and non-host sites, respectively. The results showed that inter-annual changes in carbon isotope discrimination are more sensitive to outbreaks than changes in tree-ring width. Based on carbon isotopes, we inferred that photosynthetic rates increased as a compensatory mechanism in response to insect defoliation. We reconstructed eleven insect outbreaks since 1915, which corresponded to ENSO positive phases and below-average sea surface temperatures in the central and eastern tropical Pacific Ocean. These conditions correspond to “La Niña” episodes which induce hot and dry climate conditions across the study region and these may facilitate the occurrence of D. punctatus outbreaks.     

Seasonal climatic fluctuations in the Late Triassic tropics—High-resolution oxygen isotope records from aragonitic bivalve shells (Cassian Formation,Northern Italy)

Three megalodontoid bivalves from the Upper Triassic Cassian Formation (N Italy, Dolomites) were sampled for δ¹³C and δ¹⁸O sclerochronology (n = 270). With more than 1000 described invertebrate species, the Cassian Formation has one of the best records of an Early Mesozoic tropical fauna. In addition, the Cassian Formation is one of the very few Triassic occurrences with original aragonite preservation, with all studied shells consisting of pristine aragonite. The presence of aragonite and crossed lamellar as well as fibrous prismatic shell microstructures shown for the first time for Triassic megalodontoids suggests absence or minimal impact of diagenetic alteration. The δ¹³C values range from 3.6 to 5.8‰ and show a distinct cyclicity in two studied shells whereas a third shell shows no obvious cyclicity. In one bivalve specimen, the cycles are somewhat offset from δ¹⁸O cycles and in the other specimen δ¹⁸O and δ¹³C curves are inversely correlated. Seasonal variation in freshwater runoff including nutrient input and subsequent changes in plankton productivity during dry and wet seasons may explain δ¹³C cyclicity. δ¹⁸O values show a pronounced cyclicity within each of the studied shells varying from ? 3.6 to ? 1.4‰. The variations in δ¹⁸O suggest a pronounced seasonality in Late Triassic tropical shallow waters of the western Tethys, with inferred seasonal temperature changes ranging from 24 to 32 °C. Influx of fresh water during the rainy seasons (mega-monsoon) or upwelling might also explain part of the variation in δ¹⁸O. The presented data suggest that the diverse Cassian fauna lived under conditions characterized by warm sea-surface waters with a pronounced seasonality. Similar conditions are reported for some modern tropical settings.     

Dynamics of Canadian lynx populations in space and time1

The records of Canadian lynx fur returns indicate rather regular self-repeating pattern with 9–11 yr cycles That the lynx populations over a vast geographical range fluctuate in synchrony appears to be well established The finding that the degree of synchrony levels off with increasing distance among provinces compared to increase again between the furthest–away provinces (O–shape) has largely escaped notice in previous analyses Moreover, the pattern of synchrony against distance varies depending on the period of time used m the analysis, sometimes there is O–shape, sometimes mere negative correlation, and sometimes no relationship whatsoever The entire rich pattern of lynx dynamics in space and time can be emulated by sets of local subpopulations acknowledging dispersal among populations This all suggest that local dynamics of populations cannot be fully understood unless the significance of spatial linkage of subpopulations via dispersal of individuals is acknowledged     

Resurrecting the ghost of green revolutions past: The brown planthopper as a recurring threat to high-yielding rice production in tropical Asia

The brown planthopper (BPH), Nilaparvata lugens (Stål), which periodically erupted in tropical Asian rice before the 1960s, became a major threat after farmers adopted green revolution technologies in the 1960s. Management and policy changes in the 1980s and 1990s emphasized non-insecticidal tactics to avert BPH outbreaks. However, insecticides have resurfaced as the primary means for controlling rice insect pests and tropical Asian countries have recently experienced planthopper outbreaks in record numbers. Our review of factors that have contributed to the outbreaks points to insecticides as the most tangible outbreak factor primarily because of their harmful effects on natural enemies. BPH resistance to insecticides and especially imidacloprid has increased the probability of outbreaks as farmers have applied increasing quantities of insecticide in an attempt to combat resistant populations. Similarly, heavy use of nitrogen fertilizer, especially on hybrid rice, has increased the potential for outbreaks. Other factors triggering outbreaks are less documented, but we discuss the possibility that the high outbreak synchrony in geographically separated populations of BPH may suggest a “Moran effect” such as climate that promotes an environment favoring above-average increases in BPH populations. Also, we hypothesize that BPH functions as a metapopulation and, as such, periodic outbreaks could be a natural phenomenon requiring resupply of planthoppers into vacant areas to ensure genetic linkage among subpopulations. We conclude with a series of recommendations for research and policy changes aimed at better understanding the cause of BPH outbreaks and for developing sustainable management practices to prevent future outbreaks.     

Molecular Characterization of Clostridium botulinum Isolates from Foodborne Outbreaks in Thailand, 2010

Background

Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010.

Methodology/Principal Findings

A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1–B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2).

Conclusion/Significance

This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.