D. M. Suckling

Potential of Mass Trapping for Long-Term Pest Management and Eradication of Invasive Species

Abstract Semiochemical-based pest management programs comprise three major approaches that are being used to provide environmentally friendly control methods of insect pests: mass trapping, “lure and kill,” and mating disruption. In this article, we review the potential of mass trapping in long-term pest management as well as in the eradication of invasive species. We discuss similarities and differences between mass trapping and other two main approaches of semiochemical-based pest management programs. We highlight several study cases where mass trapping has been used either in long-term pest management [e.g., codling moth, Cydia pomonella (L.); pink bollworm, Pectinophora gossypiella (Saunders); bark beetles, palm weevils, corn rootworms (Diabrotica spp.); and fruit flies] or in eradication of invasive species [e.g., gypsy moth, Lymantria dispar (L.); and boll weevil, Anthonomus grandis grandis Boheman). We list the critical issues that affect the efficacy of mass trapping and compare these with previously published models developed to investigate mass trapping efficacy in pest control. We conclude that mass trapping has good potential to suppress or eradicate low-density, isolated pest populations; however, its full potential in pest management has not been adequately realized and therefore encourages further research and development of this technology.

Potential of “Lure and Kill” in Long-Term Pest Management and Eradication of Invasive Species

ABSTRACT “Lure and kill” technology has been used for several decades in pest management and eradication of invasive species. In lure and kill, the insect pest attracted by a semiochemical lure is not “entrapped” at the source of the attractant as in mass trapping, but instead the insect is subjected to a killing agent, which eliminates affected individuals from the population after a short period. In past decades, a growing scientific literature has been published on this concept. This article provides the first review on the potential of lure and kill in long-term pest management and eradication of invasive species. We present a summary of lure and kill, either when used as a stand-alone control method or in combination with other methods. We discuss its efficacy in comparison with other control methods. Several case studies in which lure and kill has been used with the aims of long-term pest management (e.g., pink bollworm, Egyptian cotton leafworm, codling moth, apple maggot, biting flies, and bark beetles) or the eradication of invasive species (e.g., tephritid fruit flies and boll weevils) are provided. Subsequently, we identify essential knowledge required for successful lure and kill programs that include lure competitiveness with natural odor source; lure density; lure formulation and release rate; pest population density and risk of immigration; and biology and ecology of the target species. The risks associated with lure and kill, especially when used in the eradication programs, are highlighted. We comment on the cost-effectiveness of this technology and its strengths and weaknesses, and list key reasons for success and failure. We conclude that lure and kill can be highly effective in controlling small, low-density, isolated populations, and thus it has the potential to add value to long-term pest management. In the eradication of invasive species, lure and kill offers a major advantage in effectiveness by its being inverse density dependent and it provides some improvements in efficacy over related control methods. However, the inclusion of insecticides or sterilants in lure and kill formulations presents a major obstacle to public acceptance.

Invasion Biology, Ecology, and Management of the Light Brown Apple Moth (Tortricidae)

Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), the light brown apple moth (LBAM), is an important leafroller pest with an exceptionally wide host range that includes many horticultural crops and other woody and herbaceous plants. LBAM is native to southeastern Australia but has invaded Western Australia, New Zealand, Hawaii, much of England, and in 2007, it was confirmed as established in California. The discovery of this pest in California has led to a major detection and regulatory effort because of concerns about economic and environmental impacts. Its recent discovery in Sweden is also of note. LBAM has often been intercepted on imports of fruit and other plant parts, and it has the potential to become a successful invader in temperate and subtropical regions worldwide. The importance of the insect has prompted development of classical biological control programs together with a wide variety of other management interventions that can be used in integrated pest management or integrated pest eradication.

Ecological impact of three pest management systems in New Zealand apple orchards

Abstract Three apple pest-management regimes are being compared for their ecological impacts, and their ability to ensure the economic production of high-quality apples. Species diversity, pest status and fruit quality are being evaluated under: (i) conventional, (ii) integrated, and (iii) biological fruit production systems. The conventional system follows current export orchard practices with broad-spectrum pesticides, and the integrated system uses a wider range of control methods, including minimal spray applications, preferably of selective pesticides. The biological system uses mating disruption for codling moth (at one site), Bacillus thuringiensis for leafrollers, copper/slaked lime for diseases, and matting or mulches for weed control. Conventional production results in few insects being present during the season and little damage at harvest, but increasing insecticide resistance problems and changing market requirements put the sustainability of this system in doubt. In the integrated system, excellent control of Lepidoptera has been achieved using tebufenozide, with little effect on natural enemies. Further development of the system is needed, but the economics appear favourable for producing export-quality fruit in future. In the biological system, the lack of effective controls for key quarantine pests limits economic sustainability and largely restricts production to the local market. The future of this system for export production depends on innovative technology to overcome these problems.

Issues affecting the use of pheromones and other semiochemicals in orchards

Abstract Pheromones represent one of the major components of ecologically based orchard pest management. This paper reviews recent progress and highlights outstanding issues. The greatest use of pheromones has been as lures for moth to traps, although identification of attractants for other insect groups is permitting diversification. Sex pheromone traps have been widely used for decision support, usually with thresholds for intervention using either broad-spectrum, or more recently, selective insecticides. Many of the issues associated with this type of application have been resolved, but new trapping systems need to ensure that lure longevity, trap efficiency, and other factors (e.g. interpretation, thresholds) are addressed. The use of kairomones (inter-specific cues) as lures in traps raises analogous issues. Attractants for beneficials (such as sex pheromones of wasp parasitoids) can offer additional benefits, including demonstrating the level of abundance or synchrony of the biological control agent with the target pest. Pheromones have also enjoyed considerable success for direct control of orchard pests, mainly through mating disruption. The technical and biological issues have been more challenging in direct control applications. There remain major knowledge gaps in the amount of pheromone required to achieve disruption, as well as the plume structure and behavioural mechanisms that operate with different types of formulations, blends and delivery systems. There has been a recent upsurge of interest in lure and kill tactic internationally. The challenges associated with direct control by mass trapping, lure and kill or lure and infect tactics need further research.

Positive interaction of a feeding attractant and a host kairomone for trapping the codling moth, Cydia pomonella (L.).

Codling moths are attracted to acetic acid and to ethyl-(E,Z)-2,4-decadienoate, the pear ester, when presented individually. The attraction to acetic acid is thought to be a food finding behavior, whereas the pear odorant, ethyl-(E,Z)-2,4-decadienoate, may be a host kairomone. We found, in a flight tunnel study, that more male and female codling moths were captured in traps when the compounds were presented together compared to tested separately. The combination of odorants provides a stronger lure for female codling moths than exists with pear ester alone and increases the potential for using lures in managing this pest of pome fruits and walnuts.

Eradication of the Australian Painted Apple Moth Teia anartoides in New Zealand: Trapping, Inherited Sterility, and Male Competitiveness

The incursion of the native Australian painted apple moth Teia anartoides Walker into Glendene, West Auckland in May 1999, prompted an area-wide eradication programme by the New Zealand Ministry of Agriculture and Forestry Biosecurity Authority. The Australian painted apple moth is a polyphagous pest of horticulture and plantation forestry and threatened New Zealands native vegetation. The economic and ecological impact of the moths incursion was estimated at NZD 50-350 million (approximately USD 30.5-212.9 million) over 20 years if no action was taken to eradicate the insect. The eradication programme (1999-2006) used a combination of tactics, including the first use of the sterile insect technique (SIT) in New Zealand. The SIT component was added to the eradication programme in 2002 but releases started in 2003 as an end game tactic once the pest population was brought down to ca 1% of the population level in 2001-2002, as indicated by trap catches. The aerial spray programme using Bacillus thuringiensis (Berliner), subsp. kurstaki (Btk) accompanied by release of sterile males drove the wild population to extinction, with overflooding ratios up to 100:1 based on trapping data. Sterility was assessed from the egg hatch of the F1-F3 generations and competitiveness examined using emergence rates and wind tunnel flight performance. When males exposed to 100 or 160 Gy mated with non-irradiated females, there was no significant effect on female egg production, but a lower egg hatch was observed for both doses. When F1 and F2 offspring were outcrossed to fertile moths, 100 Gy irradiation gave relatively similar inherited sterility levels to 160 Gy, with full mortality achieved at the F3 generation. The lowest effective dose of radiation needed to induce inherited sterility is likely to offer the best competitiveness and mating success of the released males, representing a potential trade-off between sterility and competitiveness. Subsequently, the induced dominant lethal mutations carried by the released males (when mated to wild females), will be inherited through the surviving F1 proportion of the progeny. Moth emergence rate was not affected at 100 Gy, but the response to seek and mate with wild calling females in the wind tunnel was reduced by 33%. The use of wind tunnel for quality assurance in integrated pest management programmes is discussed.

Determinants of successful arthropod eradication programs

Abstract Despite substantial increases in public awareness and biosecurity systems, introductions of non-native arthropods remain an unwelcomed consequence of escalating rates of international trade and travel. Detection of an established but unwanted non-native organism can elicit a range of responses, including implementation of an eradication program. Previous studies have reviewed the concept of eradication, but these efforts were largely descriptive and focused on selected case studies. We developed a Global Eradication and Response DAtabase (“GERDA”) to facilitate an analysis of arthropod eradication programs and determine the factors that influence eradication success and failure. We compiled data from 672 arthropod eradication programs targeting 130 non-native arthropod species implemented in 91 countries between 1890 and 2010. Important components of successful eradication programs included the size of the infested area, relative detectability of the target species, method of detection, and the primary feeding guild of the target species. The outcome of eradication efforts was not determined by program costs, which were largely driven by the size of the infestation. The availability of taxon-specific control tools appeared to increase the probability of eradication success. We believe GERDA, as an online database, provides an objective repository of information that will play an invaluable role when future eradication efforts are considered.

Combining Tactics to Exploit Allee Effects for Eradication of Alien Insect Populations

ABSTRACT Invasive species increasingly threaten ecosystems, food production, and human welfare worldwide. Hundreds of eradication programs have targeted a wide range of nonnative insect species to mitigate the economic and ecological impacts of biological invasions. Many such programs used multiple tactics to achieve this goal, but interactions between tactics have received little formal consideration, specifically as they interact with Allee dynamics. If a population can be driven below an Allee threshold, extinction becomes more probable because of factors such as the failure to find mates, satiate natural enemies, or successfully exploit food resources, as well as demographic and environmental stochasticity. A key implication of an Allee threshold is that the population can be eradicated without the need and expense of killing the last individuals. Some combinations of control tactics could interact with Allee dynamics to increase the probability of successful eradication. Combinations of tactics can be considered to have synergistic (greater efficiency in achieving extinction from the combination), additive (no improvement over single tactics alone), or antagonistic (reduced efficiency from the combination) effects on Allee dynamics. We highlight examples of combinations of tactics likely to act synergistically, additively, or antagonistically on pest populations. By exploiting the interacting effects of multiple tactics on Allee dynamics, the success and cost-effectiveness of eradication programs can be enhanced.

Fatty acid-amino acid conjugates diversification in lepidopteran caterpillars.

Fatty acid amino acid conjugates (FACs) have been found in noctuid as well as sphingid caterpillar oral secretions; in particular, volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and its biochemical precursor, N-linolenoyl-L-glutamine, are known elicitors of induced volatile emissions in corn plants. These induced volatiles, in turn, attract natural enemies of the caterpillars. In a previous study, we showed that N-linolenoyl-L-glutamine in larval Spodoptera litura plays an important role in nitrogen assimilation which might be an explanation for caterpillars synthesizing FACs despite an increased risk of attracting natural enemies. However, the presence of FACs in lepidopteran species outside these families of agricultural interest is not well known. We conducted FAC screening of 29 lepidopteran species, and found them in 19 of these species. Thus, FACs are commonly synthesized through a broad range of lepidopteran caterpillars. Since all FAC-containing species had N-linolenoyl-L-glutamine and/or N-linoleoyl-L-glutamine in common, and the evolutionarily earliest species among them had only these two FACs, these glutamine conjugates might be the evolutionarily older FACs. Furthermore, some species had glutamic acid conjugates, and some had hydroxylated FACs. Comparing the diversity of FACs with lepidopteran phylogeny indicates that glutamic acid conjugates can be synthesized by relatively primitive species, while hydroxylation of fatty acids is limited mostly to larger and more developed macrolepidopteran species.