Canadian Forest Service Publications
Natural mating disruption in a protogynous bagworm (Lepidoptera: Psychidae). Rhainds, M. (2018). Ecological Entomology, 43(4), 543-546.
Issued by: Atlantic Forestry Centre
Catalog ID: 40414
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"1. The occurrence of natural mating disruption is investigated in the bagworm Metisa plana Walker (Lepidoptera: Psychidae). Neotenic females reproduce within a self-constructed bag made of silk and plant material, and attract males for copulation by discharging pheromone-impregnated setae into the lower section of their bag (early life pulsed release). Because pheromone release is, in part, out of the female's control, passive pheromone sources emanating from bags of post-reproductive (dead) females may compete with live pheromone-calling females.
Data collected in a plantation of oil palm during five consecutive generations of bagworms indicate that mating probabilities decline with increasing number of conspecific females per palm, reminiscent of natural mating disruption due to false trail following. Low mating success of late-emerging females further suggests that protogyny evolved to reduce late-season mating disruption due to incremental accumulation of passive sources of pheromone over time.
Natural mating disruption may be linked with life-history syndromes of female flightlessness in forest habitats: sedentary reproduction of highly fecund females on perennial hosts, combined with restricted dispersal of larval progeny that remain on their maternal host plant and travel short distances while ballooning, may lead to rapid build-up of local populations beyond levels where mating interference among females is possible."
Plain Language Summary
Mating disruption has become a major management tool to interfere with reproduction of insect pests by preventing males from locating pheromone-calling females. This study provides the first demonstration of mating disruption as a natural phenomena in field populations of bagworms (Lepidoptera: Psychidae). Natural mating disruption is characterized by large aggregations of females with low mobility, in such a way that conspecific pheromone plumes interfere with each other (intraspecific competition between pheromone sources). These findings may be relevant to population dynamics of forest insect pests with non-dispersing females that rely on pheromone for mate attraction, most notably the gypsy moth.