Accidents with scorpions are a problem in several regions of the world. In Brazil, the number of accidents is sometimes higher than 160k/year, and the responsible for most accidents and deaths is the ...yellow scorpion Tityus serrulatus. Unfortunately, there are few publications testing the effectiveness of most of the products for chemical control of scorpions. Using the pesticide Bifentol, we tested: I-the effect of the pesticide on the mortality of T. serrulatus, II-whether the scorpion avoids areas with pesticide and, III-whether it leaves the shelter if pesticide is applied. In the first experiment, we applied pesticide or water on the dorsal region of the scorpion or substrate according to treatment. For five days we noted whether the scorpion slide (dead) or clung to the substrate (alive) after turning the arena vertically to left and right. After five days, no pesticide-treated scorpions were alive while all water-treated scorpions were. In the second experiment, we placed two shelters, applied pesticide and/or water inside the shelter. We then released a scorpion on the opposite side. We scored latency to enter one of the shelters and the choice made by the scorpions. We did not find differences in latency or in the choice made. In the third experiment, we applied the pesticide or water to the shelter where the scorpion was being maintained, and, on the following day, we recorded whether the scorpion had left the shelter. None of the scorpions left the shelters and only one died. Thus, we obtained evidence that a pesticide can kill scorpions, but we did not find a dislodging effect.
Scorpionism is a worldwide problem that has already made thousands of victims, and multi-disciplinary approaches for controlling their populations are to be more successful. Hens are often mentioned ...as tools for controlling scorpions; however, systematic/experimental behavioral studies are not available. Moreover, there is no systematic information on the effect of scorpion venoms on hens. Using the venomous yellow scorpion
, the present study aimed to clarify the following aspects: (1) voracity of hens, (2) how hens react when stung, (3) the effect of scorpion stings on hen behavior during attacks, and (4) hen survivorship after feeding on scorpions.
We attracted hens with corn powder, offered them scorpions and then recorded the hen-scorpion interaction. To test the effects of the sting we manually removed the scorpion's telson.
We found that some hens ate up to six scorpions within minutes. By means of an ethogram and drawings, we showed that they exhibited several aversive behaviors when capturing scorpions. Removal of the scorpion telson stopped the aversive reactions, which was not observed in the control group. Finally, hens did not exhibit atypical behaviors after 1, 7 and 30 days and were all alive after 30 days.
This is the first empirical and video recorded study providing evidence that hens are clearly affected by scorpion venom but do not die. Therefore, they may have potential to be used in biological control of these arthropods.
Abstract
Animals use external and/or internal cues to navigate and can show flexibility in cue use if one type of cue is unavailable. We studied the homing ability of the harvestman Heteromitobates ...discolor (Arachnida, Opiliones) by moving egg-guarding females from their clutches. We tested the importance of vision, proprioception, and olfaction. We predicted that homing would be negatively affected in the absence of these cues, with success being measured by the return of females to their clutches. We restricted proprioception by not allowing females to walk, removed vision by painting the eyes, and removed the odours by removing the clutch and cleaning its surroundings. We found that vision is important for homing, and in the absence of visual cues, proprioception is important. Finally, we found increased homing when eggs were present, and that the time of the day also influenced homing. We highlight vision as a previously overlooked sensory modality in Opiliones.
The content of arthrodial membrane glands in arthropods has seldom been studied. Here, we have analyzed the proteins of the arthrodial membrane gland of the trochanter–coxa articulation of the fourth ...pair of legs in the harvestman Mischonyx cuspidatus via reverse-phase high-performance liquid chromatography (RP-HPLC), polyacrylamide gel electrophoresis (PAGE), and nanoscale liquid chromatography coupled to mass spectrometry (nLC-MS/MS) analysis. Most of the fractions studied are hydrophobic, being proteins with molecular weights of ∼28, 62, and ∼198 kDa. These proteins seem to be homologous to proteins involved in product secretion, cytoskeleton, protein binding, cellular metabolism, and antimicrobial action among others. Lubricant function is also possible based on the literature. We were able to identify 147 proteins in the inner region, 91 proteins from the outer dorsal region, and 36 proteins from the outer ventral region. Some proteins are present only in one of these regions and some are shared by one or more regions. Our work provides, to the best of our knowledge, the first proteome characterization of the content of an arthrodial membrane gland in arachnids. Dataset Identifier: ftp://massive.ucsd.edu/MSV000087195/.
Harvestmen feed on live, dead and fresh, or decomposing animals, fungi, and plant matter, being very dependent on chemoreception to find food. Herein we performed an experiment to test if individuals ...of Discocyrtus pectinifemur Mello-Leitão, 1937 (Gonyleptidae) (n = 23) behave differently when in contact with olfactory cues from different sources (rotten prey, non-rotten prey and a control). Using dead crickets in a box covered with a mesh, and recording the time the harvestmen spent in the vicinities of the box, we show that D. pectinifemur detects non-rotten prey and stays longer on it than on the other two treatments. Our results contrast with a previous study on another species, showing that we should not generalize results obtained for one species. Our data also suggest that olfactory receptors occur on the legs of these harvestmen and that D. pectinifemur might choose dietary items based on olfaction. PUBLICATION ABSTRACT
Several studies have investigated habituation in a defensive context, but few have addressed responses to dangerous stimuli. In such cases, animals should not habituate since this could cost their ...lives. Here we have stimulated individuals of the harvester
Mischonyx squalidus
with a predatory stimulus (squeezing with tweezers) in repeated trials within and between days, and measured the occurrence and magnitude of nipping, a defensive behavior. Contrary to our expectations, they did habituate to this stimulus. The probability and magnitude of response declined over trials during each of three days of testing in a typical habituation pattern. During the trials we also observed other defensive behaviors. We discuss our results mainly considering alternative defensive responses. Our data show that we lack information on (1) the role played by the ambiguity of stimuli, (2) the role played by subsequent stimuli and (3) the importance of the array of defensive behaviors of a species in understanding habituation. Although ubiquitous across animals and therefore expected, habituation is described for the first time in the order Opiliones.
•Riparian animals should benefit of actually using rivers.•We have tested predictions of a semi aquatic habit in a harvestman (Arachnida).•H. discolor swim by rowing and walking, and moves onto the ...water when disturbed.•Strictly terrestrial species did not swim or moved onto the water.•H. discolor can survive 6 h under water, as did a strictly terrestrial species.
Animals that live by rivers may benefit from being able to cross them, but behavioral adaptations are needed. Additionally, being able to remain submerged is also important if the animal moves under water. Here we asked whether the harvestman Heteromitobates discolor (Opiliones), that lives by rivers, (a) can propel itself across the water surface, (b) moves onto the water if disturbed and (c) can survive for long periods when submerged. Heteromitobates discolor exhibited two gaits on water, whereas a strictly terrestrial species was not able to propel itself. When experimentally submitted to simulated predator attack on a rock on the river, H. discolor walked onto the water, while a strictly terrestrial species did not. Finally, it was able to survive for 6 h under water, presumably due to the conspicuous air film that formed around its body, which was also observed in a strictly terrestrial species. Altogether, these observations suggest that the aquatic environment is not a barrier for regular activity and can be used as an extension of the terrestrial environment for H. discolor.
Pedipalps in laniatorid harvestmen are usually cylindrical and raptorial, but species in Cosmetidae are exceptional in that adults, but not immature, have pedipalps flattened as a spoon. These have ...never been addressed with a functional approach. We have investigated possible roles of the pedipalps in Cosmetidae in exploration, social interactions and defence. Concerning exploration, we would expect the individuals to tap the substrate with the pedipalps, as species in the suborders Eupnoi and Dyspnoi do, but this was not observed. In social interactions, pedipalps could be used for holding females during mating or to fight other males but we could not relate the spoon-shape with any of the behaviours observed. For defence, we hypothesised that the pedipalp of adults would act as a barrier preventing the potentially noxious secretion from contacting the mouth when the individual performs 'leg-dabbing'. This is typical in adult cosmetids but not in other laniatorids. Because immature cosmetids have cylindrical pedipalps, we predicted that they would not perform 'leg-dabbing'. However, immature also performed leg-dabbing and the secretion did contact the mouth. We also found no evidence of pedipalps being used for digging, drinking or self-grooming. Although we have made progress, the question remains open.
Preliminary observations suggested that the Neotropical harvestman Jussara sp. (Sclerosomatidae, Eupnoi) had a patchy distribution and a marked seasonality, comparable to species in the Northern ...hemisphere. This would be an unusual pattern, since conditions of temperature and humidity are very different between tropical and temperate environments. Using a mark-recapture method, we investigated the phenology, habitat use and individual movement of Jussara sp. in a tropical rainforest in southern Brazil. We found a very marked seasonality in the population of adults, with a positive correlation between temperature, humidity and number of adults found. Adults were found only in the wet and warm months and significantly preferred the plant Psycothria suterella (Rubiaceae) as a resting substrate, spending the days motionless on its leaves, often in groups. The same individuals were found for a maximum of three months after their first capture, 30 m from their original site of capture. At night, the harvestmen would descend from the plants, forage and interact with conspecifics on the leaf litter. In this first long term behavioral study with a representative of the suborder Eupnoi in Brazil, we provide quantitative evidence that, despite the milder climate, Neotropical harvestmen may show a seasonality similar to the seasonality shown by related species in temperate regions.
The subfamily Gonyleptinae is the second largest in Gonyleptidae, harboring over 100 species. Gonyleptinae is polyphyletic, nestled in the clade K92, and despite its richness, several species of that ...subfamily have not had their chemicals of the defensive secretions analyzed. Among these are
Gonyleptes curticornis
(Mello-Leitão, 1940) and
G. horridus
Kirby, 1819, the latter being particularly important, because it is the type species of the genus, which in turn names the subfamily Gonyleptinae.
Gonyleptes horridus
is also used in many phylogenetic analyses, be it using morphological or molecular data. The chemical study of the secretions of these two species by GC–MS and
1
H NMR showed the presence of 1-(6-isopropyl-3,4-dihydro-2H-pyran-2-yl)-methylbutanone, 1-(6-isopropyl-3,4-dihydro-2H-pyran-2-yl) isobutanone and 4-methyl-1-hepten-3-one in both species. On the other hand, 4-methyl-1-hexen-3-one was observed only in
G. curticornis
, and 7-methyl-2-octanol is exclusive of
G. horridus
. All vinyl-ketones identified have already been described for Gonyleptidae. We ran an Ancestral Character State Reconstruction (ASR) analysis under three different conditions to infer the evolution of the identified compounds (based on modified characters of a previous study) and their chemical nature (multistate character, either as alkylphenol, benzoquinone or vinyl-ketone) on a modified Gonyleptidae phylogeny. Our results corroborate previous studies that alkylphenol is the ancestral most condition, changing to benzoquinone in the ancestor of Gonyleptidae or even earlier in a grassatorean ancestor depending on the analysis. Vinyl-ketones are a synapomorphy of K92. We briefly discuss character codifications and use of weights of ASR analyses of specific compounds, which were inconclusive. 1-(6-isopropyl-3,4-dihydro-2H-pyran-2-yl) isobutanone is shared by both
Gonyleptes
species and described for the genus
Sodreana
Mello-Leitão, 1922. 1-(6-(1-methyl-propyl)3,4-dihydro-2H-pyran-2yl)2-methylbutanone and 4-methyl-1-hepten-3-one are also shared by both
Gonyleptes
species and described for
Moreiranula saprophila
. From a taxonomic standpoint, combinations of specific compounds might help to diagnose supraspecific groups but given our limited sample, such decision should be taken with care and further tested. Finally, 7-methyl-2-octanol is described for the first time in Gonyleptidae, emphasizing the chemical diverse nature in the K92 clade.
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