There is very low tolerance for blueberry maggot (Rhagoletis mendax Curran) in blueberries making it a serious pest in eastern North America. Control is focused on eliminating flies with insecticides before oviposition in fruit. Organic mulches may improve highbush blueberry production, but their effects on this pest are largely unknown. The research in this thesis evaluated compost and pine needle mulches on blueberry maggot (mature maggots, pupae, emerging flies) and predatory beetles that may consume these stages. Mulches affected fly emergence and maggot pupation. Fly emergence was reduced by 80-100% and delayed ~8 days from pupae covered with 20 cm of pine needles compared to 1 cm of soil. Emergence from 20 cm of compost was lower in wet conditions, and 5 cm of mulch did not limit emergence in the field. Pupation at increased depth reduced emergence because flies did not eclose or, if eclosed, were unable to crawl to the surface. The delay was likely due to lower temperatures at depth. No flies emerged from 1 cm in pine needles in the field probably due to high temperatures. In the laboratory, maggots pupated more deeply in pine needles than other substrates, but ~30% did not pupate in dry pine needles. Saturated soil caused ~50% of maggots to pupate on the surface. Mulching altered beetle diversity and activity/density and affected beetle predation on maggots and pupae. Compost plots in a highbush blueberry field attracted predatory carabids and staphylinids, although some staphylinids were frequent in pine needles and phytophagous carabids preferred unweeded compost plots. Attraction to compost, particularly for Pterostichus melanarius (Illiger), was due primarily to higher prey densities - earthworms and millipedes - than other treatments. This beetle consumed some maggots or pupae in soil or compost, but predation rates decreased when alternative prey was abundant. Blueberry bushes in weedy compost plots attracted many flies, but infestation rates were higher in composted bushes only in the year mulch was applied. Overall, thick mulching with pine needles contributes most significantly to blueberry maggot management. Future research should explore integration of mulch with other tactics for R. mendax control.

Natural enemies provide critical population regulation of many pest species, though their effects are not commonly incorporated into agricultural management decisions. Conservation biological control is an important tool that can be implemented to minimize pest damage, but applying it requires appropriate understanding of pest and natural enemy relationships. Through experimental cotton field trials, I identified predator: prey ratios based on key arthropod predators as action thresholds of the whitefly pest Bemisia tabaci MEAM1 (Dinsdale et al. 2010; equivalent to Bemisia argentifolii Bellows et al. 1994 [Hemiptera: Aleyrodidae]), validated their efficacy, and promoted them to cotton pest managers. This dissertation begins with a multi-year field trial where whitefly and natural enemy populations were manipulated with a series of insecticidal treatments to identify key arthropod predators. The critical abundance of four key predators necessary to suppress whiteflies was estimated through predator: prey ratios. These ratios were refined for commercial pest management and developed to conform to the current whitefly IPM framework as a simple to use management-decision tool that would be readily adopted and used by pest managers. Predator: prey ratios were then validated in 1) a second field trial, 2) commercial fields in Arizona and northern Mexico and 3) historical field trials conducted from 1997-2010, where whitefly management decisions made with the standard threshold and ratios, were compared with the standard threshold alone. I found no difference in management outcomes when decisions were made with the standard threshold alone, or with predator: prey ratios in the field trial, but analysis of potential decisions on commercial farms and with historical trial data indicated that the majority of sprays could be delayed if control decisions incorporated ratio-based thresholds. Finally, an outreach program was developed and deployed to present ratios as decision-making tools for cotton pest managers that reduce uncertainty in control decisions and optimize spray outcomes. Pest managers indicated positive changes in knowledge and a gradual adoption of ratios for decision-making. The implementation of whitefly control decisions that incorporate predator: prey ratios may reduce pest managers' uncertainty in decision-making, as well as insecticide use and management costs.

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

The goal of this study was to evaluate several sustainable turf maintenance techniques for their potential to increase beneficial insect populations, which could then provide ecosystem services including pest suppression and pollination. The three techniques in question were 1) raising mowing height in commercial and residential lawns, 2) establishing naturalized roughs on golf courses, and 3) creating pollinator refuges on golf courses through the program Operation Pollinator. We found that raising mowing heights did increase populations of some predators such as spiders and staphylinids, but did not increase predation, which was ubiquitously high because ant populations were unaffected by mowing height. In addition, we found that pests reared in high-mowed grass were less likely to survive and gained weight more slowly than when raised in low-mowed grass. On golf courses, we found that naturalized roughs and traditional roughs supported different populations of predators, but contrary to our original hypothesis, naturalized roughs had little impact on biological control on the rest of the golf course. Operation Pollinator was successful in supporting 49 species of pollinators, including rare and declining bumble bees, demonstrating that turf systems can provide valuable pollinator conservation services, especially in urban systems where pollinator habitats are already rare.

Paropsis atomaria Olivier (Coleoptera: Chrysomelidae: Paropsini), is a major pest of commercially grown eucalypts in South-East Queensland. Current management of paropsine beetles involves regular inspection and the application of chemical sprays if defoliation is severe. However, non-chemical control of plantation pests is highly desirable given the requirement to certify forest practices for sustainability, and community concerns over the use of pesticides. One way of reducing pesticide use is through conservation biological control, which requires detailed knowledge of the life history of the pest and its natural enemies. This thesis documents aspects of P. atomaria phenology, including life tables, sex ratios and damage estimates; identifies the predators, parasites, and egg and larval parasitoids of P. atomaria; and examines the ecology of the most promising natural enemy, Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) in South-East Queensland. P. atomaria adults are active from September until April and can complete up to four generations in a season. Field mortality between egg and fourth instar larvae is approximately 94%. A large proportion of this mortality can be attributed to natural enemies. The most abundant predators in eucalypt plantations were spiders, comprising 88% of all predators encountered. Egg parasitoids exerted the greatest influence on P. atomaria populations, emerging from around 50% of all egg batches, and were responsible for mortality of almost one third of all eggs in the field. Only about one percent of larvae were parasitised in the field, in contrast to paropsine pests in temperate Australia, where egg parasitism rates are low and larval parasitism rates high. Neopolycystus sp. was the only primary parasitoid reared from P. atomaria eggs, along with three hyperparasitoid species; Baeoanusia albifunicle Girault (Encyrtidae), Neblatticida sp. (Encyrtidae) and Aphaneromella sp. (Platygasteridae). This is the first record of B. albifunicle hyperparasitising Neopolycystus spp. B. albifunicle emerged from one-third of all parasitised egg batches and could pose a potential problem to the efficacy of Neopolycystus sp. as a biological control agent. However, within egg batches, hyperparasitoids rarely killed all Neopolycystus sp. with only 9% of hyperparasitised egg batches failing to produce any primary parasitoids. Total field mortality of P. atomaria through direct and indirect effects of parasitism by Neopolycystus sp. was 28%. The proportion of egg batches parasitised increased with exposure time in the field, but within-batch parasitism rate did not. In general, there was no significant correlation between parasitism rates and distance from landscape features (viz. water sources and native forest).

Brown stink bug, Euschistus servus (Heteroptera: Pentatomidae), is a recently re-emerged pest of cotton in Arizona. It has been present in southwestern desert-grown cotton since at least the early 1900’s, but dropped from primary pest status in the latter half of the twentieth century. Farmers and pest managers did not perceive it as a primary or economic pest until 2011, when elevated numbers of brown stink bugs were reported in isolated valleys of Arizona and southeastern California. Reports increased and became more widespread in the following years. In response to increased abundance of brown stink bug and corresponding cotton boll injury, research was needed to provide information to cotton farmers. First, pest managers needed information on which factors affect the susceptibility of cotton bolls to stink bug feeding (chapter 1). Young bolls are most vulnerable to stink bug injury, and injury is sustained in the first four days of feeding. In addition, research was needed to determine the effects of currently available brown stink bug chemical controls on the broader integrated pest management system in Arizona cotton (chapter 2). Current chemical control options disrupt natural enemy communities, which results in outbreaks and resurgences of other cotton pests. The negative outcomes and additional costs outweigh the benefits of brown stink bug management.

Current agroecosystem management practices have a negative effect on natural enemies and their ability to control insect pests. Conservation biological control through the addition of flowering resources can manage food resources for natural enemies. These floral resources can also provide multiple ecosystem services. Study goals were to determine if perennial Thymus vulgaris L. was attractive to natural enemies and if so, could it be a dual use resource encouraging pest management and providing harvestable product. In 2018 plots in three locations were used to examine the effect of habitat throughout the growing season on the attractiveness of T. vulgaris. Large numbers of Thysanoptera and Hemiptera were collected in all locations, represented by phytophagous Aphididae and Thripidae, and predatory Anthocoridae. Location influenced other families to varying degrees. Seasonal specimen counts were influenced by vegetation density, floral phenology, and predator/prey relationships. In 2019 replicated plots of three treatments were used to examine if harvesting plant material affected the attractiveness of T. vulgaris to natural enemies. Total specimens in 2019 were not significantly different among treatments, indicating removal of blooms did not significantly affect the attractiveness of T. vulgaris. Significant numbers of Thysanoptera and Hemiptera were again collected in all treatments, represented by phytophagous Aphididae and Thripidae. Greater numbers of Diptera and Hymenoptera were also collected. Significant numbers of Thripidae, Aphididae, Mymaridae, and Platygastridae were found in the Family level analyses. Results from both years indicate T. vulgaris was attractive to natural enemy and phytophagous Families. Data from 2018 suggest natural enemy families were attracted to alternative prey and hosts utilizing the foliage rather than flowers but the use of nectar and pollen cannot be ruled out. Data from 2019 suggest the presence of flowers played an important role in the attractiveness of T. vulgaris to micro-hymenopteran parasitoids, Syrphidae, and native Apidae. In conclusion, Thymus vulgaris has the potential to be a dual use floral resource that benefits growers through supporting native enemy populations and pollination services, as well as provide income from the harvest of foliage. It could also be used as a beneficial, harvestable floral resource in urban gardens to encourage pollinator conservation and natural pest control.

No description available.

Ecological network theory has developed from studies of static, binary trophic relationships to the analysis of quantitative, dynamic communities consisting of multiple link-types. Particularly, work has focused on the dynamic nature of ecological networks, which maintains stability in complex communities. However, there are few in situ network-level studies of the determinants of temporal and spatial variation in community structure. This thesis utilises data from a 10-year study of a host-parasitoid network and a collaborative study in an applied ecological setting to identify individual level factors important to network structure. The work aims towards an empirical, predictive framework linking adaptive foraging behaviour to ecological network structure. The results show that condition-dependent foraging behaviours structure host-parasitoid networks. The realised niches of the studied parasitoid species were generally biased towards larger host species and condition-dependent sex ratio allocation increased the likelihood that females would eclose from relatively larger hosts and males from relatively smaller hosts, which resulted in sex ratios deviating from Hamiltonian (50:50) predictions. Further, both of these aspects of behaviour are plastic, where parasitoid behaviour responded to environmental heterogeneity. Particularly, host preference behaviour conformed to an egg-/time-limitation framework, where the size dependency of the behaviour is greater when individuals have a greater likelihood of being egg-limited. Both the size-dependency and the plasticity of these behaviours differed significantly between secondary parasitoid species. This species identity effect interacted with landscape heterogeneity, which may explain some inter- and intra-specific variation in network structure. With respect to applied ecology, the results show that the benefits of natural vegetation for pest control are dependent upon the dispersal capabilities and the diet breadth of the pest and its natural enemies. The findings are evaluated towards a predictive framework for understanding the effects of future climate change on community structure and stability. We consider this framework in terms of applied ecology, particularly pest control ecosystem services provided by natural vegetation in an agricultural environment. The synergistic nature of the multiple determinants of network structure found in this thesis suggest that future studies should focus on the whole network, which is not necessarily the sum of its parts.