ArticlePublisher preview available
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Aedine mosquitoes go through unfavorable periods as dormant eggs. However, extended dormancy times lead to a depletion of egg reserves, which might be partially compensated by changes in larval-feeding behavior. Changes in larval behavior may also be induced by parasitism by mermithids probably as a strategy to reduce the impact of the parasite on the host. The most abundant floodwater mosquito in southern South America is Aedes albifasciatus (Diptera: Culicidae), a species naturally parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae). This study aimed to evaluate the behavior of fourth-instar larvae of Ae. albifasciatus from eggs with 2, 4, and 6 months of dormancy, parasitized or not by S. spiculatus. To achieve this, eight categories of behavior were defined, and then, each individual was observed for 5 min, and its behaviors and their duration were recorded. The behaviors with the highest percentage of observation time were still (50.1%) and wriggle swimming (33.6%), while those with the lowest percentage of observation time were those involving active foraging (less than 8%). A great variability in the behaviors was observed among individuals within the same treatment. The type and duration of each behavior did not vary in relation to egg dormancy time or parasitism, but parasitism affected the level of larval activity. Parasitized larvae performed, on average, fewer behaviors than non-parasitized larvae. This result supports the hypothesis that S. spiculatus parasitism affects the behavior of Ae. albifasciatus larvae by reducing their level of activity.
This content is subject to copyright. Terms and conditions apply.
Vol.:(0123456789)
1 3
https://doi.org/10.1007/s00436-021-07371-w
ARTHROPODS ANDMEDICAL ENTOMOLOGY - ORIGINAL PAPER
Behavior ofAedes albifasciatus (Diptera: Culicidae) larvae fromeggs
withdifferent dormancy timesandits relationship withparasitism
byStrelkovimermis spiculatus (Nematoda: Mermithidae)
CristianM.DiBattista1 · SylviaFischer2· RaúlE.Campos1
Received: 25 June 2021 / Accepted: 1 November 2021
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021
Abstract
Aedine mosquitoes go through unfavorable periods as dormant eggs. However, extended dormancy times lead to a depletion
of egg reserves, which might be partially compensated by changes in larval-feeding behavior. Changes in larval behavior
may also be induced by parasitism by mermithids probably as a strategy to reduce the impact of the parasite on the host.
The most abundant floodwater mosquito in southern South America is Aedes albifasciatus (Diptera: Culicidae), a species
naturally parasitized by Strelkovimermis spiculatus (Nematoda: Mermithidae). This study aimed to evaluate the behavior of
fourth-instar larvae of Ae. albifasciatus from eggs with 2, 4, and 6months of dormancy, parasitized or not by S. spiculatus.
To achieve this, eight categories of behavior were defined, and then, each individual was observed for 5min, and its behav-
iors and their duration were recorded. The behaviors with the highest percentage of observation time were still (50.1%) and
wriggle swimming (33.6%), while those with the lowest percentage of observation time were those involving active foraging
(less than 8%). A great variability in the behaviors was observed among individuals within the same treatment. The type and
duration of each behavior did not vary in relation to egg dormancy time or parasitism, but parasitism affected the level of
larval activity. Parasitized larvae performed, on average, fewer behaviors than non-parasitized larvae. This result supports
the hypothesis that S. spiculatus parasitism affects the behavior of Ae. albifasciatus larvae by reducing their level of activity.
Keywords Culicidae· Flood water mosquito· Dormant eggs· Behavioral changes· Host-parasite interactions·
Mermithidae
Introduction
Aedes albifasciatusis a floodwater mosquito widely dis-
tributed in South America (Mitchell and Darsie 1985).
The species is of sanitary importance because it is a vec-
tor of several pathogens affecting livestock and humans,
including the Western Equine Encephalitis virus (Avilés
etal. 1992) and St. Louis virus (Díaz etal. 2012). The
biology of Ae. albifasciatus is closely related to the dry/
flood cycles caused by the periodicity of rainfall events
(Ludueña Almeida and Gorla 1995). Females lay their
eggs on moist depressed ground prone to flooding and,
once embryonic development is complete, they can
either hatch immediately after a rainfall event or remain
viable for months or even more than 2years if the envi-
ronment remains dry (Campos 2008). During periods of
drought, pharate larvae remain in a dormant state inside
the egg, consuming the energy reserves until conditions
are favorable for hatching (Vinogradova 2007; Denlinger
Section Editor: Helge Kampen
We are deeply saddened by the passing of Raúl E. Campos (Oct
21th 2021)
* Cristian M. Di Battista
dibattistacm@gmail.com
1 Instituto de Limnología “Dr. Raúl A. Ringuelet, Universidad
Nacional de La Plata-CONICET, CCT La Plata, Boulevard
120 y 62 No. 1437, La Plata (B 1900), BuenosAires,
Argentina
2 Departamento de Ecología, Genética y Evolución,
andInstituto IEGEBA (CONICET-UBA), Facultad de
Ciencias Exactas y Naturales, Universidad de Buenos
Aires. Ciudad Universitaria, Pabellón 2, 4to piso. Laboratorio
54. C1428EHA, BuenosAires, Argentina
/ Published online: 11 November 2021
Parasitology Research (2022) 121:97–103
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
We described the carryover of Strelkovimermis spiculatus (Poinar and Camino) (Nematoda: Mermithidae) from mosquito larvae, the primary site of maturation, to adults. We analyzed the survival time of male and female Aedes albifasciatus (Macquart) (Diptera: Culicidae) parasitized by S. spiculatus, the time of emergence of nematodes from adult mosquitoes, and the state of parasitism in the same mosquito cohorts during the immature stages. Mosquito larvae with single and multiple parasitism (up to 11 parasites) were observed. The mortality of mosquito larvae and adults was produced in all cases where at least one mermithid emerged. The mortality of S. spiculatus showed an increasing trend in mosquito larvae with larger numbers of nematodes and was higher in larvae parasitized by eight or more nematodes. Maximum survival of parasitized adult females of Ae. albifasciatus was 38 days, while non-parasitized adult males and females survived 39 and 41 days, respectively. Strelkovimermis spiculatus mortality was observed in Ae. albifasciatus larvae with single or multiple parasitisms. The spread of mermithid parasitism in adult mosquito populations is discussed.
Article
This study aimed to evaluate the effects of egg dormancy times on susceptibility of larvae of the floodwater mosquito Aedes albifasciatus (Diptera: Culicidae) to parasitism by their natural enemy Strelkovimermis spiculatus (Nematoda: Mermithidae) and on their life history traits. Aedes albifasciatus eggs stored for 2, 4, 6, 8 and 10 months were hatched, and the larvae either exposed to S. spiculatus (treatment group) or not exposed (control group). Egg dormancy time had a negative effect on the retention of parasites, but no effect on the prevalence and intensity of parasitism or the melanization of nematodes. The survival to adulthood of control individuals decreased as dormancy time increased, whereas that of exposed individuals that remained uninfected was constant and low. A trend towards increasing development times with longer dormancy times was detected in the control group, but not in the exposed noninfected group. The results suggest nonconsumptive effects of parasites in exposed but not infected larvae from eggs with short dormancy times. In contrast, the relatively low fitness of larvae from eggs with long dormancy times regardless of their contact with the nematodes may be the result of the nutritional deprivation during the egg stage. The effect of dorma ncy time of Aedes albifasciatus eggs on the host‐parasite interaction with the nematode Strelkovimermis spiculatus was assessed for the first time. The increased egg dormancy time affects the survival and immature development time of Aedes albifasciatus, but not the susceptibility to infection by Strelkovimermis spiculatus. The low survival of larvae exposed to the nematode that avoided infection suggest nonconsumptive effects of the parasites, especially in larvae from eggs with short dormancy times.
Article
We examined manipulation of mosquito behavior by the parasitic mermithid nematode, Strelkovimermis spiculatus. This nematode species typically infects early instar host larvae and emerges after parasitic development to kill last-instar larvae. Parasitized adults, however, have occasionally been reported from field collections. We obtained low rates (1.7 to 11.5%) of parasitized adults in laboratory exposures only when Culex pipiens pipiens fourth-instar larvae nearing pupation were exposed to infective nematodes. This did not allow an adequate interval for parasitic development in immature host stages. Parasitized adult females in a multiple-choice assay were three times more likely to seek water than a blood source (63.1 vs. 20.5%), whereas uninfected females were twice as likely to seek blood than water (64%3.9 vs. 32.6%). This altered host behavior benefits the parasite by providing the only mechanism for dispersal and colonization of new host habitats while concurrently avoiding risks from the defensive behaviors associated with blood-feeding. Behavioral alternation in Cx. p. pipiens larval hosts was also examined using larvae infected as second instars to allow for a normal duration of parasitic development. As larvae neared pupation and parasite emergence, parasitized larvae became more spatially aggregated than unparasitized larvae. This altered host behavior benefits the parasite by providing a corresponding increase in post-parasite aggregation, which facilitates formation of large mating clusters and concomitantly reproductive success. Parasites derive fitness gains by overriding host autonomy, whereas hosts have zero fitness once parasitism is established, suggesting a coevolutionary response is inoperative and that the behavioral modifications may be adaptive.
Article
Immature mosquitoes alter their foraging behavior in response to variation in nutrients, predators, and temperature, with consequences on the adult stage where pathogens are transmitted. These patterns of behavior have not been described with respect to both developmental stage and environmental variation, nor has behavior been examined within an individual across instars. We hypothesized that individual larvae have distinct behavioral syndromes, and predict that the rank of foraging activity in the third instar will be correlated with foraging activity in the fourth instar for an individual across all conditions. We also hypothesized that individuals that fail to achieve adulthood forage more intensely than those that will emerge due to the need for greater resources. To examine these hypotheses, we conducted an experiment in which we exposed 96 individual Aedes aegypti L. (Diptera: Culicidae) larvae to four combinations of temperature and nutrients. We recorded larvae in the third and fourth instar, and generated time budgets of active and passive foraging behaviors. We found correlations between individual behavior in the third and fourth instar when conditions were the most stressful (cool temperatures and low nutrients). Controlling for this intra-individual behavior, there was variation between instar behaviors, but this was dependent on both temperature and nutrients. We also found that larvae that failed to pupate within 28 d before emergence foraged more intensely than those that emerged. While we found no evidence that mosquitoes have distinct behavioral syndromes in Ae. aegypti, we did find support that nutrients and temperature affect behavior differently at different instars.
Article
This book documents and illustrates the major developments in the use of nematodes for biological control of insects and slugs. It has seven parts covering the morphology and taxonomy of all nematode groups used as biological control agents; entomopathogenic nematodes; entomophilic nematodes; slug-parasitic nematodes; predatory nematodes; fungal-feeding nematodes; and critical issues and research needs for future expansion of nematode use in biological control. Nematode biology, commercial production, formulation and quality control, application technology, strategy and safety are discussed. Separate chapters are devoted to the application of nematodes in different cropping systems and the efficacy of nematodes against specific pests such as plant parasitic nematodes and fungal pathogens.
Article
A This paper proposes a regression model where the response is beta distributed using a parameterization of the beta law that is indexed by mean and dispersion parameters. The proposed model is useful for situations where the variable of interest is continuous and restricted to the interval (0, 1) and is related to other variables through a regression structure. The regression parameters of the beta regression model are interpretable in terms of the mean of the response and, when the logit link is used, of an odds ratio, unlike the parameters of a linear regression that employs a transformed response. Estimation is performed by maximum likelihood. We provide closed-form expressions for the score function, for Fisher's information matrix and its inverse. Hypothesis testing is performed using approximations obtained from the asymptotic normality of the maximum likelihood estimator. Some diagnostic measures are introduced. Finally, practical applications that employ real data are presented and discussed.