Infestation Dynamics Research Articles

Emergence of Rottboellia exaltata influenced by sowing depth, amount of sugarcane straw on the soil surface, and residual herbicide use

Mechanical sugarcane harvest without burning and continuous straw on the soil surface may affect the Rottboellia exaltata infestation dynamics in sugarcane fields. Three greenhouse experiments were conducted with the aim of studying the effects of sowing depth (0, 2.5, 5, 7.5, and 10 cm), amount of sugarcane straw on the soil surface (0, 5, 10, and 15 ton ha -1 ), and residual herbicide (clomazone, flumioxazin, imazapyr, isoxaflutole, and s-metolachlor) on the emergence of Rottboellia exaltata. For each experiment, a completely randomized design with four replicates was applied. The combination of mulch on soil surface (especially with larger amounts of straw) with deeper sowing depths provides less emergence and mass accumulation of R. exaltata. In bare soil, the sowing depth did not affect the weed dynamics. Clomazone and imazapyr were effective herbicides controlling R. exaltata regardless of the amount of straw on the soil surface. Flumioxazin was also effective in controlling R. exaltata but only under bare soil conditions. Even with 60 mm of accumulated rainfall over the 4 day period after application, the amount of flumioxazin leached to the soil was not enough to ensure the same control observed when applying the herbicide on bare soil.

SUSCEPTIBILITY OF SOME STARWEBERRY CULTIVARS TO THE INFESTATION OF TETRANYCHUS URTICAE KOCH

The relative susceptibility of six strawberry cultivars (Chandler sweet charll Branko, style , Helda and Almont) to the infestation with the two spotted mite Tetranychus urticae Koch was studied in Al kanater Research station Qualubia Governorate , through two successive seasons (2010/2011) and (2011/2012) . Evaluation of mite infestation was estimated according to the other mean number of eggs and immature stages, results showed that the population dynamics of spider mites infestation in the six cultivars appear in few numbers during the period from October until February. The infestation increased during March and reaches until February the infestation increased during march and reaches the maximum during April and decreases. The results also showed that sweetcharll and Chandler are the least preferable varieties, while Almont and Helda where the most preferable varieties to spider mite infestation . Based on these conclusions, Sweetcharll and Chandler varieties are recommended for the strawberry growers in order to depress the population density of the mite T. urticae in the strawberry fields in Egypt.

A reaction–diffusion model for the control of Eldana saccharina Walker in sugarcane using the sterile insect technique

A reaction–diffusion model is formulated for the population dynamics of an Eldana saccharina Walker infestation of sugarcane under the influence of partially sterile released insects. The model describes the population growth of and interaction between normal and sterile E. saccharina moths in a temporally variable and spatially heterogeneous environment. It consists of a discretized reaction–diffusion system with variable diffusion coefficients, subject to strictly positive initial data and zero-flux Neumann boundary conditions on a bounded spatial domain. The primary objectives are to establish a model which may be used within an area-wide integrated pest management programme for E. saccharina in order to investigate the efficiency of different sterile moth release strategies without having to conduct formal field experiments, and to present guidelines according to which release ratios, release frequencies and spatial distributions of releases may be estimated which are expected to lead to suppression of the pest. Although many reaction–diffusion models have been formulated in the literature describing the sterile insect technique, few of these models describe the technique for Lepidopteran species with more than one life stage and where F1-sterility is relevant. In addition, none of these models consider the technique when fully sterile females and partially sterile males are released. The model formulated here is also the first reaction–diffusion model formulated describing E. saccharina growth and migration, and the sterile insect technique applied specifically to E. saccharina.

Modelling the effects of the sterile insect technique applied to Eldana saccharina Walker in sugarcane

A mathematical model is formulated for the population dynamics of an Eldana saccharina Walker infestation of sugarcane under the influence of partially sterile released insects. The model describes the population growth of and interaction between normal and sterile E.saccharina moths in a temporally variable, but spatially homogeneous environment. The model consists of a deterministic system of difference equations subject to strictly positive initial data. The primary objective of this model is to determine suitable parameters in terms of which the above population growth and interaction may be quantified and according to which E.saccharina infestation levels and the associated sugarcane damage may be measured. Although many models have been formulated in the past describing the sterile insect technique, few of these models describe the technique for Lepidopteran species with more than one life stage and where F1-sterility is relevant. In addition, none of these models consider the technique when fully sterile females and partially sterile males are being released. The model formulated is also the first to describe the technique applied specifically to E.saccharina, and to consider the economic viability of applying the technique to this species. Pertinent decision support is provided to farm managers in terms of the best timing for releases, release ratios and release frequencies.

Dynamics of infestation of tracers lambs by gastrointestinal helminths under a traditional management system in the North of Tunisia.

The authors present a survey of gastrointestinal helminths of sheep on permanent pastures in the extreme north region of Tunisia (Mediterranean climate). Dynamic infestation of animals has been monitored by using batches of three tracer lambs introduced each two months during 2004 and 2005. These lambs were kept in the pens of veterinary school of Sidi Thabet (Tunisia) during three months and then necropsied. Faecal and blood samples were took from tracer lambs each two months during the whole period, and from animal flock only during 2004. The main helminth genera encountered were Trichostrongylus spp., Teladorsagia spp., Strongyloides papillosus and Anoplocephalidea; occasionaly were found Nematodirus, Oesophagostomum, Chabertia, Cooperia, Trichuris and Paramphistomum. The egg count of the ewes and lambs in the flock showed two peaks. For both ewes and lambs there is a gradual increase from January with a peak in May-June. This first peak is considered to be due to acquisition of infective larvae during the rainy and cold season, as evident from the worm burdens of tracer lambs. The second peak was exclusively observed in ewes during late autumn-early winter (November-December); it has two origins: infestation by third larvae stage and the periparturient rise. The worm burdens of tracer lambs showed that there was a gradual accumulation of nematodes from September- October, reaching a peak in March-April; a very low or naught infection is reported during the dry period (July-August). Infection by Anoplocephalidea was higher during the dry season. This study is primordial for a comprehensive control programme implementation against gastrointestinal helminths.

The ectoparasite mite Varroa destructor Anderson and Trueman in southeastern Brazil apiaries: effects of the hygienic behavior of Africanized honey bees on infestation rates

In Brazil, the ectoparasitic mite of bees Varroa destructor Anderson and Trueman (Acari: Varroidae) remains at low levels of infestation causing no major damage. However, with the introduction and possible dominance of a new haplotype (K) of the mite, usually found in areas with high infestation rates (IR), it is necessary to monitor and select beehives that are resistant to the pest in order to avoid future problems. Several factors are listed as potentially being responsible for the dynamics of mite infestation, among which hygienic behavior (HB) stands out. In this context we sought to evaluate the HB of Africanized honey bees Apis mellifera L. (Hymenoptera: Apidae) compared with the mite IR in apiaries of two municipalities of southeastern Brazil (Taubaté and Viçosa). For the municipality of Taubaté, the average IR was 4.9% (3.4 to 5.8%), while the HB averaged 98.6% (96 to 100%). In Viçosa, the average mite IR was found to be 10.0% (5.4 to 21.0%) with an average value for HB of 57.7% (0 to 79.0%). Results from this research show that IR and HB were negatively correlated (R = -0.9627, P<0.01), suggesting that hives with higher HB have lower IR.

Spatio-temporal infestation patterns of Ips typographus (L.) in the Bavarian Forest National Park, Germany

The Bavarian Forest National Park in Germany has experienced infestations of bark beetle (Ips typographus L.) since the 1980s, resulting in considerable ecological loss due to the destruction of almost 5800ha of spruce forests. Although there have been numerous investigations on the physiology and ecology of the bark beetle, until now the spatio-temporal infestation and dispersal dynamics of the bark beetle over a longer period have still not been satisfactorily understood. The understanding of the structure and the dispersal of bark beetle infestations is however of significant importance for forest management systems in order to predict the risk of outbreaks, especially in the face of climate change.The aim of this investigation was therefore (I) to analyse and describe the long term spatio-temporal infestation patterns of I. typographus in the Bavarian Forest National Park, Germany on the landscape scale, (II) to conduct investigations on spatio-temporal shifts of the focal points of bark beetle infestations from 1988 to 2010 and (III) to compare the quantitative spatio-temporal infestation patterns obtained at the landscape level with the dispersal patterns of the spatially explicit agent-based simulation model (SAMBIA) for I. typographus (Fahse and Heurich, 2011).The results of the study show that a shift in the infestation pattern of I. typographus from 1988 to 2010 occurs at different time intervals both undirectionally as well as directionally. Furthermore, the dispersal pattern of the bark beetle was recorded quantitatively and described extensively over a period of 23 years on the landscape scale.The quantification of the presence and dispersion pattern of I. typographus in the Bavarian Forest National Park allows us to gain a better understanding of the distribution pattern of the bark beetle on the landscape scale. In this way, both the pattern and structure of infestation patterns obtained for I. typographus serve as: (a) a basis for the criteria to improve the parameters of spatio-temporal simulation models, (b) a better understanding of the bark beetle pattern and existing processes such as disturbance patterns or damage patterns in the food web of spruces due to climate change, (c) a test for the hypotheses on the relationships between the presence of bark beetle and relevant habitat variables as well as (d) the compilation of forecast models on the dispersal of bark beetle. These predictions can help with the implementation of specific management strategies to prevent the dispersal of bark beetle.

Result of an epidemiological study of sea lice infestation in South Connemara, West of Ireland

Sea lice infestation patterns within a bay in Connemara, Co Galway were investigated to elucidate sources of infestation pressure and dynamics of lateral and vertical transmission of infective stages of sea lice within and between sites in a series of complex embayments. Direct measurement of sea lice infestation using sentinel cages and 3D modelling of particle distribution were used to analyse sea lice distribution. The results indicate the potential value of sentinel cages for investigating sea lice transfer between locations within a bay system and shows the potential usefulness of hydrographic modelling in informing choices of site location and sea lice management strategies.

Molecular Markers Reveal Infestation Dynamics of the Bed Bug (Hemiptera: Cimicidae) Within Apartment Buildings

The bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), has experienced an extraordinary global resurgence in recent years, the reasons for which remain poorly understood. Once considered a pest of lower socioeconomic classes, bed bugs are now found extensively across all residential settings, with widespread infestations established in multiapartment buildings. Within such buildings, understanding the population genetic structure and patterns of dispersal may prove critical to the development of effective control strategies. Here, we describe the development of 24 high-resolution microsatellite markers through next generation 454 pyrosequencing and their application to elucidate infestation dynamics within three multistory apartment buildings in the United States. Results reveal contrasting characteristics potentially representative of geographic or locale differences. In Raleigh, NC, an infestation within an apartment building seemed to have started from a single introduction followed by extensive spread. In Jersey City, NJ, two or more introductions followed by spread are evident in two buildings. Populations within single apartments in all buildings were characterized by high levels of relatedness and low levels of diversity, indicative of foundation from small, genetically depauperate propagules. Regardless of the number of unique introductions, genetic data indicate that spread within buildings is extensive, supporting both active and human-mediated dispersal within and between adjacent rooms or apartments spanning multiple floors.

House Infestation Dynamics and Feeding Sources of Triatoma dimidiata in Central Veracruz, Mexico

Chagas disease is endemic in the state of Veracruz, Mexico, and we investigated here the dynamics of house infestation by Chagas disease vectors to understand disease transmission and design effective control interventions. Bug collections in 42 rural villages confirmed the widespread distribution of Triatoma dimidiata in central Veracruz. Unexpectedly, collection data further indicated a clear pattern of seasonal infestation by mostly adult bugs. Analysis of feeding sources with a polymerase chain reaction-heteroduplex assay indicated a frequent feeding on humans, in agreement with the high seroprevalence previously observed. Feeding sources also confirmed a significant dispersal of bugs between habitats. High dispersal capabilities and seasonal infestation may thus be a shared characteristic of several of the T. dimidiata sibling species from this complex. It would thus be critical to adapt vector control interventions to this behavior to improve their efficacy and sustainability, as the control of T. dimidiata has been notoriously challenging.

Quantidade de transposição do líquido pulverizado sobre palha de cana-de-açúcar com pontas de pulverização tipo leque e cone

A colheita da cana-crua promove aumento de restos culturais de cobertura morta sobre o solo. Esse novo componente altera a dinâmica de infestação de plantas daninhas e atua também como barreira física e química à ação dos herbicidas. Visando melhorar a qualidade da deposição dos herbicidas no solo, objetivou-se neste trabalho avaliar a eficiência das pontas de pulverização e sua capacidade de transposição sobre a palha de cana-deaçúcar. O experimento foi instalado em Maringá-PR. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 8 x 7, sendo oito pontas de pulverização (AD 110 02, ADIA 110 02, TT 110 02, TTIA 110 02, CV-IA02, MAG 2, ST 02 e TJ60 110 02) e sete quantidades de palha (0, 1, 2, 4, 6, 8 e 10 t ha-1). Assim, observou-se que grandes quantidades de palha reduzem a quantidade do líquido pulverizado que foi depositado na superfície coletora. As pontas de pulverização leque antideriva (AD 110 02) e cone vazio com indução de ar (CV-IA 02) foram as mais eficientes.

Dinâmica da infestação de Brevipalpus phoenicis (Geijskes, 1939) (Acari:Tenuipalpidae) em pomares cítricos da Bahia, Brasil

Em duas regiões da Bahia - Litoral Norte (LN) e Recôncavo Baiano (RB) quantificaram-se a dinâmica espaço-temporal da infestação de plantas cítricas pelo ácaro Brevipalpus phoenicis. Dez pomares de cada região foram avaliados mensalmente (de abril de 2008 a fevereiro de 2011), nos quais 21 plantas tiveram três frutos/planta vistoriados com lupa de 10x para registrar a presença ou ausência do ácaro. A proporção média de plantas infestadas variou entre 0,38 e 1,0. Em frutos, a proporção mínima de infestação foi 0,10 e máxima de 0,73 no LN e 0,66 no RB. O processo de infestação foi sazonal, com mais unidades infestadas na primavera-verão (Nemenyi, p<0,05). A análise de densidade espectral mostrou a ocorrência de dois tipos de ciclos: um com período aproximado de 2 meses, possivelmente relacionado com a biologia do ácaro e outro anual, decorrente da interação vetor-hospedeiro-ambiente. Em ambas as regiões, a aleatoriedade caracterizou o padrão espacial da infestação do ácaro intra e interpomares. Não foram observados sintomas de leprose dos citros no RB.

DEVELOPMENT OF THE ROSY APPLE APHID WITHIN ITS HABITAT: SOME STRUCTURAL AND PHYSIOLOGICAL ASPECTS IN APPLE TREES

Plant architecture governs living conditions of herbivores. In fruit trees, the perennial structure is modulated by training and pruning which may affect pests. The effect of tree architecture manipulation on the development of the rosy apple aphid Dysaphis plantaginea (RAA) was investigated from 2002 to 2009 in apple orchards. The first step (2002-2005) consisted in comparing the Centrifugal Training system (CT) with extinction pruning (i.e., selective removal of spurs at bud-burst to favour light penetration and spur fruiting) to the Solaxe system (OS) with no extinction pruning. RAA infestation was significantly lower in CT trees 2 years out of 4. The hypothesis of a within-tree structural effect on RAA development was proposed beside possible microclimatic and mechanical (i.e., infested shoot removal) effects. In a second step (2007-2008) we investigated the relationships between the branch structure and RAA development in both training systems. In CT trees, branches displayed higher shoot orders compared to OS. Infestation dynamics presented similar patterns in both systems, but RAA spreading rate was lower in CT trees. These results suggested that the complexity of the aerial system due to higher branching orders affected insect movement within its habitat. In 2009 a glasshouse experiment with oneyear- old potted apple trees was carried out to test the combined effect of simplified architectures (1 vs. 2 extension shoots per tree) and of three nitrogen regimes on the development of RAA artificially set on the trees. There was no significant difference in aphid numbers at peak infestation between architectural treatments although RAA migration was earlier with 1 extension shoot. Moreover, a higher aphid population was shown for intermediate nitrogen regimes highlighting the pest response to trophic parameters. These experiments confirm the importance of tree training strategies in the management of orchard pests. They provide avenues to design sustainable orchard systems based on cultural methods giving partial control of pests.

Infestation of tracer lambs by Fasciola hepatica in Tunisia: determining periods for strategic anthelmintic treatments

Ovine fasciolosis causes high morbidity and mortality rates, resulting in large economic losses to the sheep industry in northern Tunisia. The authors surveyed ovine fasciolosis (Fasciola hepatica infestation) in a Barbarine sheep flock in the humid region of Tunisia (Sejnane, Governorate of Bizerte) over two consecutive years, 2004 to 2005. To assess the dynamics of fluke infestation, a total of 36 tracer lambs were introduced into the flock successively, in groups of three, every two months, and their infestations were monitored by coproscopy and necropsy. Coproscopic analysis revealed high mean percentages of infestation of 60% and 65% for flock lambs and ewes, respectively. Similarly, a high percentage of infestations was recorded in the tracer lambs (more than 70%) post mortem. Significant fluctuations in infestation dynamics were observed in the tracer lambs, and three distinct infestation periods were identified: a period of very low, non-constant infestation risk during the warm period (from July to October); a high-risk period from March to June, and a third period with a variable but constant infestation risk (from November to February). Based on these results, the authors propose strategic flukicide treatments with triclabendazole, aimed at reducing mollusc infestation and subsequent pasture contamination by metacercariae, during two main periods: in September and in February, just before the reactivation of the molluscs from aestivation and hibernation, respectively.

Evaluation of Spatially Targeted Strategies to Control Non-Domiciliated Triatoma dimidiata Vector of Chagas Disease

BackgroundChagas disease is a major neglected tropical disease with deep socio-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic populations of triatomine vectors, but non-domiciliated vectors still have to be controlled efficiently. Designing control strategies targeting these vectors is challenging, as it requires a quantitative description of the spatio-temporal dynamics of village infestation, which can only be gained from combinations of extensive field studies and spatial population dynamic modelling.Methodology/Principal FindingsA spatially explicit population dynamic model was combined with a two-year field study of T. dimidiata infestation dynamics in the village of Teya, Mexico. The parameterized model fitted and predicted accurately both intra-annual variation and the spatial gradient in vector abundance. Five different control strategies were then applied in concentric rings to mimic spatial design targeting the periphery of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when control was applied only to the 33% of households closest to the village periphery. Peri-domicile cleaning was able to eliminate up to 60% of the vectors, but at the periphery of the village it has a low effect, as it is ineffective against sylvatic insects. The use of lethal traps and the management of house attractiveness provided similar levels of control. However this required either house attractiveness to be null, or ≥5 lethal traps, at least as attractive as houses, to be installed in each household.Conclusion/SignificanceInsecticide and insect screens used in houses at the periphery of the village can contribute to reduce house infestation in more central untreated zones. However, this beneficial effect remains insufficient to allow for a unique spatially targeted strategy to offer protection to all households. Most efficiently, control should combine the use of insect screens in outer zones to reduce infestation by both sylvatic and peri-domiciliated vectors, and cleaning of peri-domicile in the centre of the village where sylvatic vectors are absent. The design of such spatially mixed strategies of control offers a promising avenue to reduce the economic cost associated with the control of non-domiciliated vectors.

Infestation of the invasive mollusc Crepidula fornicata by the native shell borer Cliona celata: a case of high parasite load without detrimental effects

The temporal prevalence of the widespread boring sponge Cliona celata and its effects were analysed in a population of the invasive mollusc Crepidula fornicata. This mollusc produces extra shell material when infested with the endolithic sponge, suggesting that infestation may be detrimental for C. fornicata growth and/or reproduction. For 37 months, size, sex, female reproductive status and sponge-infestation stage were recorded for 300 individuals sampled every month in the Bay of Morlaix (France). In the 12,049 individuals examined, the prevalence of C. celata was high with a monthly average of 43.1% of the individuals hosting the sponge. The relative proportion of heavily infested individuals generally increased over time. Nevertheless, a cyclic decrease occurred every 10 months, suggesting putative episodes of mortality of heavily infested individuals. The gregarious behaviour of the mollusc seemed to promote the high prevalence of the sponge, which may propagate through contact between neighbouring C. fornicata individuals. Due to the sex-size relationship in protandrous C. fornicata, females were far more infested than males. We did not find evidence for a cost of producing extra shell material on somatic growth or on female fertility, and the boring sponge is unlikely to substantially affect the sex-change patterns in C. fornicata. The limited effects of the endolithic sponge on C. fornicata contrasts with the documented damage to some local species, including commercially exploited shellfish, suggesting that C. fornicata may alter the infestation dynamics in the surrounding native community. Dedicated studies are now needed to investigate the extent and mechanisms of these species interactions.

Dynamics of infestation and losses of stored maize due to the larger grain borer (Prostephanus truncatus Horn) and maize weevils (Sitophilus zeamais Motschulsky)

The dynamics of infestation and losses of stored maize due to the larger grain borer (Prostephanus truncatus Horn) and maize weevils (Sitophilus zeamais Motschulsky) were investigated in Tanzania. In single species populations, significantly higher maize damage (P ≤ 0.05) was caused by P. truncatus (23.3%) compared to S. zeamais (6.4%). Weight losses caused by P. truncatus were higher (12.7%) than for S. zeamais (6.7%) under similar conditions. A higher proportion of P. truncatus in the initial infestation population led to significantly higher (≤0.05) maize damage compared to equal or higher proportions of S. zeamais. Irrespective of the initial number of S. zeamais, population size increased to levels higher than for P. truncatus. Maize losses in unimproved storage structures were >80% compared to <2.5% in improved structures under natural infestation. Inter-specific competition appeared to influence the dynamics of infestation, damage levels and weight losses. The first two months of storage were critical for damaging insect populations to build up.

Characterization of the Dispersal of Non-Domiciliated Triatoma dimidiata through the Selection of Spatially Explicit Models

BackgroundChagas disease is a major parasitic disease in Latin America, prevented in part by vector control programs that reduce domestic populations of triatomines. However, the design of control strategies adapted to non-domiciliated vectors, such as Triatoma dimidiata, remains a challenge because it requires an accurate description of their spatio-temporal distributions, and a proper understanding of the underlying dispersal processes.Methodology/Principal FindingsWe combined extensive spatio-temporal data sets describing house infestation dynamics by T. dimidiata within a village, and spatially explicit population dynamics models in a selection model approach. Several models were implemented to provide theoretical predictions under different hypotheses on the origin of the dispersers and their dispersal characteristics, which we compared with the spatio-temporal pattern of infestation observed in the field. The best models fitted the dynamic of infestation described by a one year time-series, and also predicted with a very good accuracy the infestation process observed during a second replicate one year time-series. The parameterized models gave key insights into the dispersal of these vectors. i) About 55% of the triatomines infesting houses came from the peridomestic habitat, the rest corresponding to immigration from the sylvatic habitat, ii) dispersing triatomines were 5–15 times more attracted by houses than by peridomestic area, and iii) the moving individuals spread on average over rather small distances, typically 40–60 m/15 days.Conclusion/SignificanceSince these dispersal characteristics are associated with much higher abundance of insects in the periphery of the village, we discuss the possibility that spatially targeted interventions allow for optimizing the efficacy of vector control activities within villages. Such optimization could prove very useful in the context of limited resources devoted to vector control.

The impact of lianas on 10 years of tree growth and mortality on Barro Colorado Island, Panama

Summary 1. Lianas compete intensely with trees, but few studies have examined long‐term effects of liana infestation on tree growth and mortality. We quantified the effects of lianas in tree crowns (n = 2907) and rooted within 2 m of trees (n = 1086) on growth and mortality of 30 tree species from 1995 to 2005 on Barro Colorado Island (BCI), Panama, documented liana infestation in tree crowns in 1996 and 2007 to determine the dynamics of liana infestation, and quantified liana infestation in the crowns of 3231 additional canopy trees (d.b.h. ≥20 cm) in 2007 to compare with the same metric determined by previous studies in 1967 and 1980. 2. Severe liana infestation increased tree mortality: 21% of liana‐free trees in 1996 had died by 2007, whereas 42% of trees with more than 75% of the crown infested by lianas in 1996 had died by 2007. 3. Liana infestation of tree crowns significantly reduced tree growth, particularly on sun‐exposed trees. The proximity of rooted lianas significantly reduced the growth of shaded trees. 4. Liana infestation was dynamic: 10.9% of trees with severe liana infestation in their crowns in 1996 had shed all of their lianas by 2007 and 5.3% of trees with no lianas in their crown in 1996 had severe liana infestation in 2007. 5. Liana infestation was common: lianas were present in 53% of trees of the 30 focal species. Including lianas rooted within 2 m of the tree increased this percentage to 78%. Using both above‐ and below‐ground measures may provide a better estimate of liana competition than either measure alone. 6. Liana infestation is increasing on BCI. Lianas were present in the crowns of 73.6% of canopy trees (d.b.h. ≥20 cm). Liana canopy infestation was 57% higher than in 1980 and 65% higher than in 1967, which is consistent with reported increases in liana abundance, biomass, and leaf and flower production. 7. Synthesis. We used one of the largest studies ever conducted on lianas to confirm the negative effects of lianas on tree growth and survival over 10 years. Liana infestation of trees was widespread, dynamic and increasing on BCI.

Patterns of house infestation dynamics by non-domiciliatedTriatoma dimidiatareveal a spatial gradient of infestation in rural villages and potential insect manipulation byTrypanosoma cruzi

Chagas disease is a major vector-borne parasitic disease in Latin America, primarily transmitted to humans by triatomine vectors. Non-domiciliated triatomine species such as Triatoma dimidiata in the Yucatan peninsula, Mexico, can transiently invade houses and are emerging as a major challenge to control Trypanosoma cruzi transmission to humans. We analyzed the spatio-temporal spreading of house infestation by T. dimidiata in four rural villages. Triatomines were collected in four rural villages over a 2 years period, and the spatio-temporal patterns of infestation were analyzed. Triatomines were consistently more abundant at the periphery of villages than in centers, indicating a much higher risk of T. cruzi transmission at the periphery. Male T. dimidiata were found further in the center of the village, while females remained closer to the periphery, suggesting differential dispersal capabilities between sexes, although the timing of dispersal appeared identical. Surprisingly, infected females were consistently collected in houses much further from the surrounding bushes than non-infected females, while the distribution of males was unaffected by their T. cruzi infection status, suggesting an increased dispersal capability in infected females. The spatial structure of infestation should be taken into account for the prioritization of vector control activities within villages, and spatially targeted interventions may be explored. A potential vector manipulation by T. cruzi, observed for the first time in triatomines, may favor parasite transmission to new hosts.