INTEGRATED MANAGEMENT OF COTTON PESTS: PLANT GENETICS, BIOLOGICAL CONTROL, AND NOVEL METHODS OF PEST ESTIMATION
Title: Oviposition behaviors and ontogenetic embryonic characteristics of the western tarnished plant bug, Lygus hesperus
Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 27, 2011
Publication Date: March 15, 2012
Citation: Cooper, W.R., Spurgeon, D.W. 2012. Oviposition behaviors and ontogenetic embryonic characteristics of the western tarnished plant bug, Lygus hesperus. Journal of Insect Science. 12:36.
Interpretive Summary: The western tarnished plant bug is a major pest of fruit, vegetable, and field crops in the western United States. Plant bugs insert their eggs into plant tissues. Consequently, some aspects of egg-laying behavior and subsequent egg development cannot be directly observed. We developed a novel observation method using a semi-transparent egg-laying substrate that permitted direct observation of egg laying and egg development. Female plant bugs inserted their mouthparts into the egg-laying substrate at or near the same location where an egg was subsequently deposited. The total time required to lay an egg was about 30 seconds. Several distinct phases of egg development were documented, some of which can now be recognized from eggs inserted into plant tissue. Unfertilized eggs did not exhibit any of these phases of development. Our descriptions of egg-laying behavior and egg development will be useful in studies of interactions between plant bugs and their hosts, and in efforts to identify factors that influence egg development and hatch.
Lygus hesperus Knight (Hemiptera: Miridae) is a key pest of fruit, vegetable, and field crops in the western United States but many aspects of L. hesperus ecology are poorly documented. A sound understanding of oviposition behavior and characterization of the phases of embryonic development would be useful in studies of interactions between L. hesperus and its hosts, and in efforts to better understand the developmental consequences of low temperatures. Because L. hesperus insert their eggs into the host, most of the egg is obscured from view and some aspects of oviposition, and of subsequent egg development, cannot be observed directly. A novel observational method which took advantage of the propensity for L. hesperus to oviposit in semi-transparent sheets of agarose was used to observe oviposition and subsequent embryonic development. L. hesperus females stylet-probed prospective oviposition sites, and during oviposition the ovipositor followed the path of these probes. Oviposition, from insertion to withdrawal of the ovipositor, required ˜30 seconds. Identifiable phases of embryo development included egg swelling, katatrepsis, appearance of body segments and appendages, development of red pigmentation in the eyes and terminal antennal segments, and formation of the 3rd embryonic cuticle. These phases were observed at about 0.3, 0.4, 0.5, 0.6, and 0.8 of the total duration between oviposition and hatch, respectively. Infertile eggs did not exhibit any of these phases. Our descriptions of embryonic development will facilitate the study of L. hesperus egg biology and ecology, and permit estimates of egg population age structure and prediction of egg hatch.