Containment attempts to stop the spread of an insect outbreak and is normally used against pests which have been introduced from other lands (exotics) or native pests that have eruptive population dynamics.
Containment is frequently employed against exotic insects that have been introduced from another country. The origin of these outbreaks is usually clearly defined, often around ports of entry, and so it is possible to set up quarantines and embargoes to prevent the movement of the pest into new regions. However, because many insects can fly long distances, can be born on air currents for many miles, and can be transported by humans and their vehicles, halting their spread is no simple matter.
EXAMPLE
Gypsy Moth. Although females of the European gypsy moth cannot fly, they often lay their egg masses on vehicles and are thereby transported across country (slide). It is generally not practical to stop every vehicle travelling across the US so the major effort to contain the moth employs pheromone traps to detect new infestations (slide) followed by vigorous efforts to eradicate the infestation, usually with Bt sprays. Increasing trade with Russia in recent years has heightened the threat to the Pacific States from the Asian variety of the gypsy moth, whose females can fly. Several incipient infestations have been eradicated from the west coast (click here for more about Asian gypsy moths).
Containment strategies against native pests only makes sense when the insects exhibit eruptive population dynamics. In these cases, the outbreak spreads from an epicenter which can sometimes be detected and its boundaries delineated. However, it is usually more difficult to apply containment strategies to native pests than to exotics because the epicenters may not be so obvious or accessible.
EXAMPLE
Southern pine beetle. The population dynamics of the southern pine beetle, Dendroctonus frontalis, is characterized by the development of well-defined local infestations or "spots" which tend to spread out with time (slide). For a view of a large southern pine beetle spot, go to Virginia Tech southern pine beetle page (click here). The growth of the spot can sometimes be contained by preventing beetles from moving from one tree to the next, say by felling a buffer strip across the leading edge of the infestation (slide). The more common practice in small spots is to fell all infested trees plus a buffer of green trees across the expanding front and then leave the felled trees there, the so-called "cut-and-leave" tactic (slide). For more information go to the Virginia Tech southern pine beetle pages (click here).
<Use BACK key to return to Sessions>