Plant Mediated Interactions: Lower Sawfly Survival on Pines Previously Browsed by Moose

Insect herbivore performance and arthropod communities can be affected by mammalian grazing and browsing via altered plant communities and vegetation structure. Far less is known about whether changes to plant architecture can cause similar effects. Browsing generated changes to within plant architecture could potentially have large consequences for arthropod communities, herbivore survival and eventually damage to plants. This study investigates plant-mediated effects of ungulate browsing on arthropod predator communities and on the survival of herbivorous insects. More specifically we studied how different levels of ungulate browsing (1) influenced the arthropod predator community on Scots pine (Pinus sylvestris) and (2) affected the survival of the European pine sawfly (Neodiprion sertifer). We related these response variables to browsing-inflicted changes in pine architecture. An observational study of generalist arthropod predators on pine trees revealed a trend toward a quadratic response of ants to browsing intensity—i.e., a higher abundance of ants on moderately browsed trees and lower abundance on intensively browsed trees. A field survey of sawfly larvae revealed a 19% lower larval survival on browsed compared to un-browsed pines, but no difference in survival comparing pines with moderate and high intensity of browsing. A structural equation model revealed that moose generated changes to pine architecture had only a small effect on sawfly larval survival, suggesting additional mediating pine traits affected by browsing. We conclude that insect survival can be altered by ungulate browsing, which could affect damage levels.

Arthropods as Vertebrate Predators: A Review of Global Patterns

Arthropod predators preying on vertebrates is generally overlooked in ecological studies, as it is not typically observed in nature and generally considered a rare event. This is likely due to the cryptic nature of these predatory events, the relatively small size of arthropods, and the difficulty in collating published data which is scattered throughout the literature. Although arthropods are known to readily hunt and consume vertebrates, very little is known about these predatory events. In this study, a systematic literature review was conducted to provide a conceptual framework, identify global patterns, and create a searchable database of arthropod preying on vertebrates. This study represents the largest global assessment of arthropod predators and vertebrate prey with over a thousand recorded observations collated from over 80 countries across every continent except Antarctica, where no arthropod predator exists. Arthropod predators were represented by six classes (insects, arachnids, centipedes, and crustaceans: Malacostraca, Ostracoda, Hexanauplia) and over 80 families. Vertebrate prey were represented by five classes (birds, mammals, reptiles, amphibians, fish) and 160 families. The most common prey were frogs consisting of over a third of all observations. The most commonly preyed reptiles were nearly all lizards, half of mammal prey were bats, nearly a third of fish were Cypriniformes, and half of bird prey were passerines. Spiders represented over half of all predatory events found and were the main predator for all vertebrates except birds, which were preyed mostly upon praying mantises. However, prey varied between spider families. For insects, true bugs (Hemiptera) and beetles preyed mostly on amphibians while the aquatic Odonata larvae preyed on amphibians and fish. Decapod predators were observed preying equally between reptiles, birds, and amphibians; with centipedes preying mainly on reptiles and mammals. Predation was mostly recorded from the Americas and Australia, with countries and regions varying between predator and prey groups. This study demonstrates that arthropods are indeed an overlooked predator of vertebrates. Recognizing and quantifying these predator-prey interactions is vital for identifying patterns and the potential impact of these relationships on shaping vertebrate populations and communities. Understanding the possible threat of arthropod predators may be especially important to improve the success of conservation efforts by accounting for predators which may currently be overlooked.

DIVERSITY OF ARTHROPOD PREDATOR IN SWAMP RICE FIELDS IN SOUTH SUMATERA

The abundance and diversity of arthropod in agro ecosystem depend on the level of synthetic pesticide contamination. This study aimed to explore, identify and analyze the diversity and abundance of predatory arthropods in swamp rice fields treated with pesticide application (in Pemulutan) and without pesticide application (in Musi 2). The swamp rice fields in Pemulutan are bordered by village, river and forest. The methods were survey and direct observation on 3 ha and 2 ha of swamp rice fields in Pemulutan and Musi 2, Palembang. Sampling of predatory arthropods were conducted at 20, 50, 80 and 110 days after rice planting using pitfall trap. Identification of predatory arthropods was conducted at Laboratory of Entomology showing that the arthropod collected consisted of 17 species of insects and 9 species of Arachnida. In Pemulutan Ogan Ilir were found 19 species (10 species of insect and 9 species of Arachnida) at the village area. In the area that was bordered by river were found 8 species (7 insect and 1 Arachnida). In the area bordered by forest were found 22 species (10 species of insects and 12 species of Arachnida). The diversity level, number of species, and arthropod specimen in the field without pesticide application at Musi 2 were higher than those in the fields with pesticide application in Pemulutan.