Invasive Insects: Management Methods Explored

Abstract

Invasive insect species can act as a plague across the globe, capable of vast expansion and rapid, proliferate reproduction. The spread of pathogens of serious diseases such as malaria and Zika virus and damages to agricultural crops number some of the afflictions invasive insects provide to humans alone. Additionally, an escape from predators can fail to keep invasive insects in check, providing potential threats such as extra resource competition to native species when insects invade. A variety of methods are employed to combat these invasive species, each with their own varying levels of success. Here, we explore the more traditional methods of invasive insect pest control, such as pesticides and biological control. In lieu of several unintended consequences resulting from such practices, we suggest some should be abandoned. We evaluate the potential of new techniques, in particular, those with a genetic component, regarding the costs, benefits and possible consequences of implementing them. And finally, we consider which techniques should be the focus of future research, if we truly wish to manage or even eradicate invasive insects in their introduced lands.

Keywords: RNA interference; biocontrol; gene editing; invasive insect; pesticide.

Fig. 1.

Invasive insects can provide a slew of problems in different countries. (a) German wasps (Vespula germanica) are one of two species to invade New Zealand in the last century, consuming up to 90% of the honeydew produced in beech forests to the detriment of native species (Moller et al. 1991). (b) The little fire ant or electric ant Wasmannia auropunctata has spread globally from its native range of central and South America. Impacts have included eliminating arachnid populations and outcompeting 17 of the 28 ant taxa known in several Galápagos islands, and even eating the hatchlings of tortoises (Lubin 1984). (c) The cabinet beetle or Khapra Trogoderma granarium is a serious threat to groundnut preservation, with the larvae voraciously feeding/contaminating stored food, indiscriminate of whether the food is plant or animal matter, and is considered one of the 100 most invasive pests in the world (Lowe et al. 2000). (d) The Argentine stem weevil Listronotus bonariensis originally caused damages of US$48–164 per annum to New Zealand exotic pasture (Popay et al. 2011). Initial biocontrol methods were met with great success, but parasitoid levels have since fallen (Tomasetto et al. 2017). (e) The gypsy moth Lymantria dispar was intentionally introduced into Massachusetts in the 1800s, it has become a major pest for U.S. forests and ornamental trees, with control estimates of US$11 million annually (Campbell and Schlarbaum 1994). (f) The silverleaf whitefly Bemisia tabaci is a pest of vegetable, grain legume, ornamental, and cotton production via phloem feeding and as a vector of plant pathogenic viruses, with a global distribution (Jones 2003).

Fig. 2.

(a) In typical Mendelian inheritance, an individual carrying a sex-linked dominant mutation will pass such a mutation on to, and therefore be expressed in, half of their offspring. In a gene drive system, however (b), the selected gene has the potential to be inherited by all offspring. A CRISPR cassette containing a guide RNA guides the Cas9 protein to the desired site to create a DSB. The cassette is inserted into the break while the strands anneal together, a process known as HDR. With the presence of a germline promoter, this gene-editing results in all-female offspring carrying the mutation, which has the potential to act as an effective method for invasive insect control.