Predators Of Herbivorous Insects Research Articles

Functional specialization for pollination by scoliid wasps and solitary bees of Ampelopsis glandulosa (Vitaceae)

The insect visitors to the flowers of Ampelopsis glandulosa (Vitaceae) were surveyed in western Japan. This plant species has cymose inflorescences with many greenish open flowers that contain copious nectar. Diverse insect species visit the flowers and the number of wasps was greater than that of bees. The most frequent visitor at all study sites was the scoliid wasp Scolia oculata. Solitary halictine and andrenid bees were also relatively frequent visitors at some sites. Because a large amount of yellow pollen from A. glandulosa was attached to the bodies of both wasps and bees, they were considered to be effective pollinators. Although honey-bees and vespid wasps were also frequent visitors at many sites, a negligible amount of yellow pollen was found to be attached to the bodies of a majority of these; therefore, they were not considered to be effective pollinators. Vespid wasps are predators of herbivorous insects and observations revealed that they are nectar thieves of A. glandulosa. Because diverse insects were attracted to A. glandulosa flowers, these flowers appear to be generalists, however, only short-tongued scoliid wasps, halictine bees, and andrenid bees appeared to be effective pollinators. These results therefore suggest that A. glandulosa is functionally specialized for short-tongued hymenopteran pollinators. This study adds to a growing body of work on specialized wasp pollination, a system hitherto mostly known from South Africa.

Polybia Fasticiosuscula (Hymenoptera: Vespidae) Foraging Activity Patterns

Prey identification expands our knowledge on social wasps and their interactions as predators of herbivorous insects. The objective was to characterize the Polybia fastidiosuscula Saussure (Hymenoptera: Vespidae) foraging pattern in Jul 2015. Polybia fastidiosuscula workers returning to the nest were intercepted and captured with an entomological net at the Universidade Federal de Vicosa in Vicosa, Minas Gerais State, Brazil. Seven sampling sessions of 13 h each, from 6:00 AM to 7:00 PM, were carried out, totaling 91 sampling h. The prey collected (182 insects) were Lepidoptera (caterpillars, 92.6%), Araneae (3.1%), Diptera (2.5%), and Orthoptera (nymphs, 1.8%). Mean (± SD) wasp weight was 17.4 ± 3.3 mg, and mean weight of prey transported was 5.2 ± 2.5 mg. A P. fastidiosuscula worker can carry a load of about 30% of their own body weight. The foraging preference, principally of lepidopteran caterpillars, suggests that P. fastidiosuscula has potential as a natural enemy in integrated pest management programs.

Insecticide residues in bats along a land use-gradient dominated by cotton cultivation in northern Benin, West Africa.

Many regions in Africa are currently being converted from subsistence to cash crop farming such as cotton. Agricultural intensification is usually accompanied by increased use of pesticides, which can have an impact on non-target organisms. Bats are particularly sensitive to insecticide loads while providing substantial ecosystem services as predators of herbivorous insects. In this study, pesticide residues in bats in a landscape in northern Benin were investigated, which spanned a land use gradient from an agricultural zone dominated by cotton farms, through a buffer zone, and into a national park. Insecticides used in cotton cultivation, such as endosulfan, chlorpyrifos, flubendiamide, and spirotetramat, as well as persistent insecticides such as bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT), lindane, and aldrine, were analysed. Insecticide residues detected in bats comprised DDT, endosulfan, and their corresponding transformation products. Maximum concentrations in the sampled bats were 11.2 mg/kg lipid of p,p'-DDE (median: 0.0136 mg/kg lipid) and 0.797 mg/kg lipid of β-endosulfan (median: below detection limit [DL]). While insecticide concentrations were below lethal concentrations our data suggest that DDT had probably been recently used in the study region, and larger scale use would pose an increased risk for bat populations due to the high biomagnification of DDT.

Consequences of Fragmentation of Tropical Moist Forest for Birds and Their Role in Predation of Herbivorous Insects

ABSTRACTThe consequences of habitat alteration on the role of understory insectivorous birds as predators of herbivorous insects in tropical forests are poorly understood. To examine whether fragmentation may affect the top–down controls of herbivory, we compared the number of species, individuals, and the community structure of insectivorous birds between fragments and continuous tropical moist forest in Mexico. We also registered insect herbivore abundances and conducted a larvae predation experiment to evaluate the potential role of insectivorous birds as predators of herbivorous insects. We recorded 63 bird species from 22 families, 43 percent of which were insectivorous birds. Species richness, abundance, and diversity of the avian community were higher in continuous forest compared with forest fragments. For insectivorous birds in particular, there was low similarity in avian insectivore communities between forest types, and forest fragments had more heavily dominated communities of avian insectivores. During the dry season, forest fragments presented significantly higher predation rates on artificial caterpillars, and lower abundance of herbivorous Lepidoptera larvae, compared with continuous forest. Furthermore, there was a significant negative correlation between artificial caterpillar predation rate and larval Lepidoptera abundance, with higher rates of predation in sample sites of low Lepidoptera abundance. Hence, the potentially greater light in the dry season combined with a more dominated avian insectivore community in forest fragments may facilitate increased predation by avian insectivores, resulting in a decline in abundance of larval Lepidoptera, with implications for the process of insect‐driven herbivory in forest fragments.