ABSTRACT
En este trabajo, se hipotetiza el periodo de aislamiento, la inmovilización y la migración inversa que sucedidos durante la pandemia del COVID-19 (años 2020 y 2021) incrementaron la capacidad de caza de las comunidades Matsigenkas asentadas en el Parque Nacional del Manu (PN Manu). Para esto, evaluamos los cambios en los patrones del volumen de extracción de la caza a través de un monitoreo participativo utilizando el modelo de monitoreo de la intensidad de cacería. Se evidenció que hubo un incremento de la capacidad de caza de las comunidades nativas. Los volúmenes más altos de extracción y el mayor incremento del número de cazadores, esfuerzo y área de cacería se dieron en el periodo 2020 - 2021, cuando las medidas de aislamiento e inmovilización fueron establecidas. Sin embargo, hubo una disminución de los indicadores para la temporada 2021 - 2022, año en que se flexibilizaron las medidas de aislamiento y se dio la reactivación económica, permitiendo que las personas retornaran a sus actividades económicas y educativas fuera del PN Manu. Se debe considerar que los efectos de solo un año de pandemia sobre los medios de subsistencia de las comunidades pudieron afectar la abundancia de la fauna silvestre, donde el mono maquisapa y mono choro (especies vulnerables) tuvieron altos incrementos de extracción. Por otro lado, nuestros resultados indicarían que el buen estado de conservación del PN Manu permitió la provisión de alimentos a las comunidades durante la pandemia. Se recomienda la planificación de programas que mitiguen los efectos negativos de pandemias o eventos semejantes, además se señala la importancia de medir el grado de resiliencia de las principales especies de caza, ya que el incremento de caza también podría tener efectos sobre la seguridad alimentaria de estas comunidades.
In this work, we hypothesize that the period of isolation, immobilization, and reverse migration that occurred during the COVID-19 pandemic (years 2020 and 2021) increased the hunting capacity of the Matsigenka communities settled in Manu National Park (PN Manu). To evaluate this, we assessed changes in hunting volume patterns through participatory monitoring using the hunting intensity monitoring model. It was evident that there was an increase in the hunting capacity of Matsigenka communities. The highest extraction volumes and the greatest increase in the number of hunters, hunting effort, and hunting area occurred in the 2020-2021 period, the year in which isolation and immobilization measures were established. However, there was a decrease in the indicators for the 2021-2022 period, the year in which isolation measures were relaxed and economic reactivation occurred, allowing people to return to their economic and educational activities outside PN Manu. It should be considered that the effects of only one year of the pandemic on the livelihoods of the communities could have affected the abundance of wildlife, with vulnerable species such as maquisapa monkeys and choro monkeys experiencing high extraction rates. On the other hand, our results indicate that the good conservation status of PN Manu provided food provisions for the communities during the pandemic. Planning programs to mitigate the negative effects of pandemics or similar events is recommended, and the importance of measuring the resilience of key hunting species is emphasized, as increased hunting could also have effects on the food security of these communities.
ABSTRACT
By increasing plant diversity in agroecosystems, it has been proposed that one can enhance and stabilize ecosystem functioning by increasing natural enemies' diversity. Food web structure determines ecosystem functioning as species at different trophic levels are linked in interacting networks. We compared the food web structure and composition of the aphid- parasitoid and aphid-hyperparasitoid networks in two differentially managed plum orchards: plums with inter-rows of oats as a cover crop (OCC) and plums with inter-rows of spontaneous vegetation (SV). We hypothesized that food web composition and structure vary between OCC and SV, with network specialization being higher in OCC and a more complex food web composition in SV treatment. We found a more complex food web composition with a higher species richness in SV compared to OCC. Quantitative food web metrics differed significantly among treatments showing a higher generality, vulnerability, interaction evenness, and linkage density in SV, while OCC presented a higher degree of specialization. Our results suggest that plant diversification can greatly influence the food web structure and composition, with bottom-up effects induced by plant and aphid hosts that might benefit parasitoids and provide a better understanding of the activity, abundance, and interactions between aphids, parasitoids, and hyperparasitoids in plum orchards.
ABSTRACT
All species interact in complex antagonistic or mutualistic networks that may be driven by turnover in species composition due to spatiotemporal environmental filtering. Therefore, studying differences in insect communities along environmental gradients may improve our understanding of the abiotic and biotic factors that shape the structure of trophic networks. Parasitoids are interesting models to do so, due to their intimate eco-evolutionary relationship with their hosts. We explored the differences in cereal aphid-parasitoid food webs during the winter among nine localities in Chilean central-south valley, along a gradient of 1200 km from north (29° S) to south (40° S). We hypothesized that diapause incidence would increase in the coldest areas, resulting in a lower number of parasitoid species active during the winter. Consequently, network specialization, generality, and vulnerability indexes should increase with decreasing latitude, which implies fewer and more weakly connected links per parasitoid species through an increased fraction of basal host species. Based on the severity of winter, three areas along the explored gradient were distinguished, but clustering did not follow a clear north-south latitudinal gradient. Instead, few differences were observed in overwintering strategies, with very low levels of diapause in all localities, and no major differences in food-web composition. The major differences along the gradient were the relative abundances of the different aphid, parasitoid and hyperparasitoid species, with higher levels of spatial and temporal variation observed for the less abundant species. Our results provide a better understanding of the activity and abundance of aphid parasitoids during winter in relation to climatic conditions.
Subject(s)
Aphids , Animals , Food Chain , Chile , Host-Parasite Interactions , SeasonsABSTRACT
The green peach aphid, Myzus persicae (Sulzer), is a pest mainly controlled with insecticides, and it can acquire resistance through different mechanisms. Pyrethroids can select the knock down resistance (kdr) mutation in M. persicae and can also produce lethal and sub-lethal effects on its main parasitoid, Aphidius colemani Viereck. However, kdr-resistant M. persicae exhibits a reduced response to alarm pheromone and increased vulnerability to natural enemies. To study the effects of sub-lethal concentrations of a pyrethroid on the aphid-parasitoid interaction, kdr-resistant and susceptible M. persicae were confronted with A. colemani with residual sub-lethal concentrations of λ-cyhalothrin. The behavior, survival, and development of parasitoids were evaluated after exposure to λ-cyhalothrin LC20 for adult parasitoids (0.52 mg/liter) for susceptible (Mp-SS, 0.56 mg/liter) and kdr-resistant M. persicae (Mp-RR, 12.15 mg/liter). The foraging and oviposition behaviors of the parasitoids were not affected by the lower parasitoid or Mp-SS LC20. Conversely, the higher Mp-RR LC20 significantly reduced parasitoid walking, the frequency of sting attempts, and successful stings, as well as aphid defensive behaviors, such as walking, kicking, and jerking. Therefore, the higher vulnerability of kdr-resistant M. persicae could not be capitalized by A. colemani parasitoids under a high concentration of λ-cyhalothrin. Similarly, the parasitism rate, survival of progeny, productivity, sex ratio (proportion of females), longevity, and adult body mass were reduced, and the development time increased with a higher Mp-RR LC20. Our results suggest that A. colemani could efficiently control kdr-resistant and susceptible M. persicae only at lower λ-cyhalothrin concentrations.
Subject(s)
Aphids , Prunus persica , Pyrethrins , Wasps , Animals , Host-Parasite Interactions , Nitriles , Pest Control, BiologicalABSTRACT
The use of cover crops can promote the abundance and early arrival of populations of natural enemies. Cereal cover crops between orchards rows could encourage the early arrival of the parasitoid Aphidius platensis, as they offer alternative winter hosts (e.g., Rhopalosiphum padi), enhancing the control of Myzus persicae in spring. However, the preference for and suitability of the alternative host must be addressed beforehand. To evaluate the potential of this strategy, we assessed host preference using behavioural choice tests, as well as no-choice tests measuring fitness traits, when developing on both host species. One source field for each aphid population from the above hosts was chosen. There was a clear choice for R. padi compared to M persicae, independently of the source, probably due to more defensive behaviours of M. persicae (i.e., kicks and escapes). Nevertheless, both aphid species were suitable for parasitoids' development. The female progeny developed on R. padi were larger in size, irrespective of their origin. According to our results, in peach orchards with cereals sown between peach trees during the autumn, where we expect when R. padi populations will no longer be available during spring, A. platensis should be able to switch to M. persicae.
