<P> Economic costs from invasive species can be separated into direct costs through production loss in agriculture and forestry, and management costs . Estimated damage and control cost of invasive species in the U.S. alone amount to more than $138 billion annually . Economic losses can also occur through loss of recreational and tourism revenues . When economic costs of invasions are calculated as production loss and management costs, they are low because they do not consider environmental damage; if monetary values were assigned to the extinction of species, loss in biodiversity, and loss of ecosystem services, costs from impacts of invasive species would drastically increase . The following examples from different sectors of the economy demonstrate the impact of biological invasions . </P> <P> It is often argued that the key to reducing the costs of invasive species damage and management is early detection and rapid response, meaning that incurring an initial cost of searching for and finding an invasive species and quickly controlling it, while the population is small, is less expensive that managing the invasive population when it is widespread and already causing damage . However, an intense search for the invader is only important to reduce costs in cases where the invasive species is (1) not frequently reintroduced into the managed area and (2) cost effective to search for and find . </P> <P> Weeds reduce yield in agriculture, though they may provide essential nutrients . Some deep - rooted weeds can "mine" nutrients (see dynamic accumulator) from the subsoil and deposit them on the topsoil, while others provide habitat for beneficial insects or provide foods for pest species . Many weed species are accidental introductions that accompany seeds and imported plant material . Many introduced weeds in pastures compete with native forage plants, threaten young cattle (e.g., leafy spurge, Euphorbia esula) or are unpalatable because of thorns and spines (e.g., yellow starthistle). Forage loss from invasive weeds on pastures amounts to nearly US $1 billion in the U.S. alone . A decline in pollinator services and loss of fruit production has been caused by honey bees infected by the invasive varroa mite . Introduced rats (Rattus rattus and R. norvegicus) have become serious pests on farms, destroying stored grains . </P> <P> Invasive plant pathogens and insect vectors for plant diseases can also suppress agricultural yields and nursery stock . Citrus greening is a bacterial disease vectored by the invasive Asian citrus psyllid (ACP). Because of the impacts of this disease on citrus crops, citrus is under quarantine and highly regulated in areas where ACP has been found . </P>

Which activity resulted in the accidental introduction of an invasive species
find me the text answering this question