Although glyphosate is widely used for weed pest control, it might have negative side effects on natural enemies. Wolf spiders are one of the most representative predators found on soybean crops in Uruguay, preying on a wide variety of potential pests. However, the sublethal effects that pesticides might have on this group have been poorly explored for South American species. Herein, we explored the sublethal effects of glyphosate on the functional response of the wolf spider Hogna cf. bivittata against three potential pest insects, namely ant (Acromyrmex sp.), caterpillar (Anticarsia gemmatalis), and cricket (Miogryllus sp.). We contaminated residually adult females of the species Hogna cf. bivittata with glyphosate (Roundup®) and compared their functional response against non-contaminated spiders. We did not observe any mortality during the study. We found that overall Hogna cf. bivittata showed a functional response type II against crickets and caterpillars but no functional response to ants. Contaminated spiders killed less ants and caterpillars in comparison to the control group, probably as a consequence of the irritating effects of glyphosate. We did not observe differences in functional response to crickets at the evaluated densities, probably as a consequence of the low capture rate against this prey. Although glyphosate does not specifically target spiders, it might have negative sublethal effects on native predators such as Hogna cf. bivittata. Further studies should explore effect of glyphosate on other native predators from South American crops.
- MeSH
- Formicidae MeSH
- glycin analogy a deriváty toxicita MeSH
- Gryllidae MeSH
- můry MeSH
- pavouci účinky léků MeSH
- pesticidy toxicita MeSH
- predátorské chování účinky léků MeSH
- zemědělské plodiny MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Uruguay MeSH
Spider wasps of the genus Minagenia have evolved koinobiontism as a relatively rare life strategy within the widely diversified hymenopteran family Pompilidae. In this study, we evaluated several aspects of the parasitic strategy of the wasp Minagenia sp. (hereafter, Minagenia) - namely host specificity, ontogeny, and sex determination as a function of host size. We found that Minagenia is highly host specific, being associated only with the genus Lycosa from the family Lycosidae, namely Lycosa u-album (Mello-Leitão, 1938), Lycosa erythrognatha (Lucas, 1836) and Lycosa poliostoma (Koch, 1847) with a parasitism incidence of 18.9%, 15.8% and 12.5%, respectively. Both ecological and taxonomical host traits determine the host selection and sex allocation of Minagenia female wasps. Charnov's host-size model explains Minagenia's host-size-dependent sex ratio in combination with the effect of host development stage, host species, and host foraging strategy. We also found that the final instar larva of Minagenia induces behavioural changes in spider hosts. The manipulated spider builds a protective silk chamber as a shelter for parasitoid pupation. Our results suggest that host manipulation seems to be narrowly connected with koinobiont life style throughout Hymenoptera. This study provides new information about the host-parasitoid koinobiont life strategy among spider wasps, which probably arose convergently in distant taxonomical groups within Pompilidae.
- MeSH
- chování zvířat MeSH
- interakce hostitele a parazita MeSH
- larva fyziologie MeSH
- rozmnožování fyziologie MeSH
- sršňovití fyziologie MeSH
- stadia vývoje MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Predators are traditionally classified as generalists and specialists based on the presence of adaptations that increase efficiency of prey capture and consumption and selection of particular prey types. Nevertheless, empirical evidence comparing foraging efficiency between generalist and specialist carnivores is scarce. We compared the prey-capture and feeding efficiency in a generalist and a specialist (araneophagous) spider predator. By using two related species, the generalist Harpactea rubicunda (Dysderidae) and the specialist Nops cf. variabilis (Caponiidae), we evaluated their fundamental trophic niche by studying the acceptance of different prey. Then, we compared their predatory behavior, efficiency in capturing prey of varying sizes, feeding efficiency, and nutrient extraction. Nops accepted only spiders as prey, while Harpactea accepted all offered prey, confirming that Nops is stenophagous, while Harpactea is euryphagous. Further, Nops displayed more specialized (stereotyped) capture behavior than Harpactea, suggesting that Nops is a specialist, while Harpactea is a generalist. The specialist immobilized prey faster, overcame much larger prey, and gained more mass (due to feeding on larger prey) than the generalist. Both the specialist and the generalist spider extracted more proteins than lipids, but the extraction of macronutrients in the specialist was achieved mainly by consuming the prosoma of the focal prey. We show that the specialist has more efficient foraging strategy than the generalist.
- MeSH
- druhová specificita MeSH
- fyziologická adaptace MeSH
- fyziologie výživy zvířat * MeSH
- pavouci fyziologie MeSH
- predátorské chování * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Trophic specialisation can be observed in species with long-term constant exploitation of a certain prey in all populations or in a population of a species with short-term exploitation of a certain prey. While in the former case the species would evolve stereotyped or specialised trophic adaptations, the trophic traits of the latter should be versatile or generalised. Here, we studied the predatory behavioural adaptations of a presumed myrmecophagous spider, Oecobius navus. We chose two distinct populations, one in Portugal and the other in Uruguay. We analysed the actual prey of both populations and found that the Portuguese population feeds mainly on dipterans, while the Uruguayan population feeds mainly on ants. Indeed, dipterans and springtails in Portugal, and ants in Uruguay were the most abundant potential prey. In laboratory trials O. navus spiders recognised and captured a wide variety of prey. The capture efficiency of the Portuguese population measured as components of the handling time was higher for flies than for ants, while that of the Uruguayan population was higher for ants. We found phenotypic plasticity in behavioural traits that lead to increased capture efficiency with respect to the locally abundant prey, but it remains to be determined whether the traits of the two populations are genetically fixed. We conclude that O. navus is a euryphagous generalist predator which shows local specialisation on the locally abundant prey.
- MeSH
- biologická adaptace MeSH
- hmyz fyziologie MeSH
- pavouci fyziologie MeSH
- potravní řetězec MeSH
- predátorské chování MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Portugalsko MeSH
- Uruguay MeSH
