Academic literature on the topic 'Liposcelis decolor'

The insect growth regulator methoprene was evaluated for control of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), Liposcelis entomophila (Enderlein), Liposcelis paeta Pearman (Psocoptera: Liposcelididae), and Lepinotus reticulatus Enderlein (Trogiidae) at application rates of 1, 5, and 10 ppm on maize, wheat, and rice. Methoprene did not completely suppress progeny production during the 40-day test period, but did cause a significant reduction in adult progeny in all psocid species at the application rates of 5 and 10 ppm. At 1 ppm, numbers of adults were reduced for all species on wheat and maize, but only for L. paeta on rice. Nevertheless, the numbers of nymphs present after 40 days generally were not reduced, relative to the controls. Methoprene applied at rates of 1 to 10 ppm to stored grain would not provide adequate control of psocids.

AbstractMicrosatellite markers were used to investigate the genetic structure among invasive L. decolor populations from Australia and a single international population from Kansas, USA to determine patterns of dispersal. Six variable microsatellites displayed an average of 2.5–4.2 alleles per locus per population. Observed (HO) heterozygosity ranged from 0.12–0.65 per locus within populations; but, in 13 of 36 tests, HO was less than expected. Despite low levels of allelic diversity, genetic structure estimated as θ was significant for all pairwise comparisons between populations (θ=0.05–0.23). Due to suspected null alleles at four loci, ENA (excluding null alleles) corrected FST estimates were calculated overall and for pairwise population comparisons. The ENA-corrected FST values (0.02–0.10) revealed significant overall genetic structure, but none of the pairwise values were significantly different from zero. A Mantel test of isolation by distance indicated no relationship between genetic structure and geographic distance among all populations (r2=0.12, P=0.18) and for Australian populations only (r2=0.19, P=0.44), suggesting that IBD does not describe the pattern of gene flow among populations. This study supports a hypothesis of long distance dispersal by L. decolor at moderate to potentially high levels.

Abstract Psocids are damaging stored-product pests. In this study, eggs and early-instar nymphs, adults, and all life stages of Liposcelis entomophila, L. decolor, L. bostrychophila, and L. paeta were subjected to 43, 50, or 75% (Control) relative humidity (RH) for 2, 4, 6, 8, 10, 12, 14, or 16 d at 30.0°C. All adults of these species died within 8 d at both 43 and 50% RH, except for L. bostrychophila, which required 12 d at 50% RH for 100% mortality to occur. For all life stages and eggs and early-instar nymphs, maximum survival times (times to 100% mortality) at 43 or 50% RH for L. entomophila, L. decolor, L. bostrychophila, and L. paeta, were 8 and 10 d, 8 and 12 d, 12 and 14 d, and 12 and 16 d, respectively. During this study, numbers of nymphs and adults of all species 14 d after the RH treatments increased within the 75% RH Control arenas. Different species and life stages responded differently to 43 and 50% RH, as time to kill all stages of the four psocid species was 8–12 and 10–16 d, respectively. Results indicate that using a specific RH environment may be effective in psocid management.

This thesis is a comprehensive treatment of the invasion genetics of two major Liposcelis pest species, Liposcelis bostrychophila Badonnel and L. decolor (Pearman), in Australian grain storage systems. Randomly amplified polymorphic DNA (RAPDs) and microsatellite DNA markers were used to investigate Liposcelis invasions in grain storage systems. The RAPD and microsatellite markers used provided insights into the genetic diversity of L. bostrychophila and L. decolor populations both in Australia and internationally, providing information integral to gaining an understanding of Liposcelis invasions in Australian grain storage systems. The thesis is divided into discrete chapters, and for each chapter an abstract is provided. Chapter 1 provides background on Liposcelis invasions in Australia in relation to the biology of Liposcelis species, the infrastructure of the Australian grain industry and the history of invasions in comparison to other invasive invertebrate species. The use of DNA and PCR technologies to investigate Liposcelis invasions are discussed and the aims and objectives of this thesis are introduced. Chapter 2 uses RAPDs to trace the geographic origin of L. bostrychophila populations in Australia from unknown geographic sources internationally. High levels of clonal genetic diversity among populations of L. bostrychophila in Australia and internationally were found. In addition, multiple introductions, from a wide range of international source populations were detected and this obscured our ability to accurately determine the geographic origin of L. bostrychophila in Australia. Given the high clonal genetic diversity found in populations of parthenogenetic L. bostrychophila in Australia, diagnostic Wolbachia PCR primers were used in Chapter 3 to investigate whether L. bostrychophila individuals from these populations were infected by Wolbachia and if infected, to investigate the strain of Wolbachia characteristic of Australian L. bostrychophila populations. Results from Chapter 3 provide the first evidence of multiple Wolbachia infection from strains A and B in Australian L. bostrychophila populations. Chapter 4 details the extensive molecular procedures undertaken to isolate microsatellite loci from Liposcelis decolor using both enrichment and nonenrichment methods. Microsatellite loci were optimised for use in PCR in single individuals following extensive troubleshooting. Troubleshooting efforts focused on elucidating the factors controlling the specificity, efficiency and sensitivity of the PCR to amplify small Liposcelis individuals known to be rich in lipids and proteins, all inhibitory to PCR. In Chapter 5 lipids and proteins were investigated from L. decolor and L. entomophila to determine total concentrations and characterize the lipids from these species. This chapter discusses whether the lipid and protein concentrations found were of a level that could be inhibitory to PCR in relation to the microsatellite techniques used in this study. From the work conducted in both Chapters 4 and 5 a troubleshooting protocol adapted for use in L. decolor was developed and implemented to determine the endogenous and exogenous parameters responsible for the function and reproducibility of PCR of microsatellite loci in L. decolor. In Chapter 6, the novel microsatellites isolated from L. decolor in Chapter 4 were used to investigate genetic structure and gene flow from Australian and international L. decolor populations. In Chapter 6 the first evidence of population differentiation, gene flow and dispersal in invasive populations of L. decolor was found. In addition, the eleven microsatellites isolated from L. decolor were cross-amplified in five other important Liposcelis pests, L. bostrychophila, L. entomophila, L. paeta, L. rufa, and L. corrodens, from which informative population genetic studies are now possible. Finally, Chapter 7 comprises the thesis synopsis, implications and future research.