China
Africa
Explore chapters and articles related to this topic
Biotic factors and interactions among organisms
Published in Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz, Agroecology, 2023
Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz
In contrast, a parasitoid derives energy and nutrients during its life cycle from a single prey (or host) individual and is often smaller than that individual. The typical parasitoid (most often an insect) lays its egg inside the prey; the egg hatches and produces a larva; the larva consumes the prey from the inside and then emerges as an adult as the prey dies. Because their hosts are single individuals, parasitoids are classified, ecologically speaking, as parasites and they are said to parasitize their hosts. Parasitoids, however, are not to be confused with other parasites (or parasites strictly defined), which draw resources from their hosts and weaken them but generally don’t kill them. Animals with this feeding lifestyle can parasitize both plants and other animals, but very few of those in the latter category take crop pests as their hosts, essentially eliminating them as possible natural enemies. And those that parasitize plants, such as the tiny soil-dwelling pathogenic nematodes, are among the most problematic pests of crop plants.
Agricultural production: assessment of the potential use of Cas9-mediated gene drive systems for agricultural pest control
Published in Journal of Responsible Innovation, 2018
Maxwell J. Scott, Fred Gould, Marcé Lorenzen, Nathaniel Grubbs, Owain Edwards, David O’Brochta
Insecticides, and to a lesser extent biological control (parasitoids), have been used to control many species of Hemiptera. The plant-feeding habits of many of these insects make it likely that future population control strategies are likely to include the use of plant-based systemic RNA interference (RNAi) to some extent (Upadhyay et al. 2011). Basic functional genomics tools still need to be developed for many of these species to aid in identifying genes that can act as targets for plant-based gene silencing strategies. Genomic studies that elucidate the physiological genetics of Hemipterans will be important in designing and producing plants that are resistant to these insects and the diseases they carry. In particular, plant-feeding Hemiptera act as vectors of plant pathogenic viruses through a variety of mechanisms. Some insects essentially only serve as physical carriers of viruses; viruses simply attach to specialized regions of their mouthparts. In other cases, viruses infect the insect, in ways that may or may not involve viral replication, and then circulate within the insect (Whitfield, Falk, and Rotenberg 2015). The high degree of specificity involved with these virus/insect interactions involves a number of insect proteins and genes. However, in most cases, validating the function of these proteins/genes has been difficult because of the absence of genetic technologies that allow for rigorous testing of structure/function relationships. Consequently, there has been no confirmed identification of insect receptor proteins responsible for specific interactions with circulative viruses (Blanc, Drucker, and Uzest 2014). Thus, without a better molecular understanding of virus-host interactions it will be difficult to develop plant-resistance mechanisms or gene-drive systems that will inhibit viral transmission. Further, multiple anti-pathogen genes would need to be developed for species such as B. tabaci that are vectors for several viruses. For these species, a population suppression strategy is more feasible. While RNAi-based gene downregulation, through ingestion or injection, has proven highly effective in several species of Hemipterans, including Acyrthosiphon pisum, Lygus lineolaris, Oncopeltus fasciatus, Rhodnius prolixus, N. lugens, and B. tabaci (You et al. 2013), more sophisticated genetic manipulations involving both gene knockout and transgenic technologies are needed for the types of genetic experiments required to validate putative virus-receptor proteins in these insects.