Natural enemies of the bagworm, Metisa plana Walker (Lepidoptera: Psychidae) and their impact on host population regulation

Comparison of <I>Diadegma insulare</I> (Hymenoptera: Ichneumonidae) and <I>Microplitis plutellae</I> (Hymenoptera: Braconidae) as Biological Control Agents of <I>Plutella xylostella</I> (Lepidoptera: Plutellidae): Field Parasitism, Insecticide Susceptibility, and Host-Searching

“…In order that M. similis can reproduce continuously, the use of chemical agents that directly kill the host must be considered carefully. In other words, chemical control of S. exigua and S. litura larvae must not be excessive during high population density and overlapping generations (Basri et al 1995).…”

Establishing the evidence base for maintaining biodiversity and ecosystem function in the oil palm landscapes of South East Asia

“…It has for some time been assumed in the industry that beneficial planting of understorey vegetation provides vital levels of 'silent' biological control [69]. It is known that experimentally providing an artificial sugar supply significantly prolongs the life of parasitoids [75], and it is thought that the provision of nectar-rich understorey species will therefore support a greater diversity of these natural enemies. This should in turn help ensure that parasitoids do not become desynchronized from their hosts, which Basri et al [75] showed was the major factor that caused outbreaks in the bagworm pest Metisia plana.…”

“…It is known that experimentally providing an artificial sugar supply significantly prolongs the life of parasitoids [75], and it is thought that the provision of nectar-rich understorey species will therefore support a greater diversity of these natural enemies. This should in turn help ensure that parasitoids do not become desynchronized from their hosts, which Basri et al [75] showed was the major factor that caused outbreaks in the bagworm pest Metisia plana. However, we urgently need explicit demonstrations of exactly how beneficial planting might aid conservation biological control so that the practice might be adopted in a more rational manner.…”

“…(a) Biocontrol Oil palm pests tend to be native species that have transferred to the introduced oil palm monocultures [73]. Although there is a wide range of economically important pest taxa, the most prominent are lepidopteran insect defoliators, principally bagworms (Psychidae) and nettle caterpillars (Limacodidae) [69,[74][75][76]. Historically, general control methods such as blanket spraying were used in an attempt to prevent outbreaks, but it became the consensus that this spraying affected the natural enemy populations of the oil palm pests [69].…”

Bionomics of Bagworms (Lepidoptera: Psychidae)

“…A high density of conspecifics or defoliation of host plants limits the availability of food and reduces the performance of larvae (8), often resulting in larval death (56, 89), reduced body size (31, 42, 55, 56, 81, 85), and low reproductive output of females (7,17,41,42,85). Individual variation in fitness caused by a limited availability of food has consequences at the population level: For example, the body size and reproductive output of females are negatively correlated with population density (7,17,85,87), which may influence the size of (4,9,20,102), but few studies have evaluated the relation between population density and the incidence of parasitism, predation, or disease. Top-down population regulation is generally believed to arise from an increasing level of mortality caused by natural enemies with an increased population density of herbivores, either on a temporal or spatial scale.…”