Xingeng Wang - Academia.edu (original) (raw)

Papers by Xingeng Wang

Research paper thumbnail of Optimal Conditions for Diapause Survival of Aprostocetus fukutai, an Egg Parasitoid for Biological Control of Anoplophora chinensis

Insects

Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora c... more Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora chinensis, a high-risk invasive pest of hardwood trees. The parasitoid overwinters as diapausing mature larvae within the host egg and emerges in early summer in synchrony with the egg-laying peak of A. chinensis. This study investigated the parasitoid’s diapause survival in parasitized host eggs that either remained in potted trees under semi-natural conditions in southern France or were removed from the wood and held at four different humidities (44, 75, 85–93 and 100% RH) at 11 °C or four different temperature regimes (2, 5, 10 and 12.5 °C) at 100% RH in the laboratory. The temperature regimes reflect overwintering temperatures across the parasitoid’s geographical distribution in its native range. Results show that the parasitoid resumed its development to the adult stage at normal rearing conditions (22 °C, 100% RH, 14L:10D) after 6- or 7-months cold chilling at both the semi-natural ...

Research paper thumbnail of Drosophila suzukii (Diptera: Drosophilidae): A Decade of Research Towards a Sustainable Integrated Pest Management Program

Journal of Economic Entomology

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as spotted-wing drosophila (SW... more Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as spotted-wing drosophila (SWD), is a pest native to Southeast Asia. In the last few decades, the pest has expanded its range to affect all major European and American fruit production regions. SWD is a highly adaptive insect that is able to disperse, survive, and flourish under a range of environmental conditions. Infestation by SWD generates both direct and indirect economic impacts through yield losses, shorter shelf life of infested fruit, and increased production costs. Fresh markets, frozen berries, and fruit export programs have been impacted by the pest due to zero tolerance for fruit infestation. As SWD control programs rely heavily on insecticides, exceedance of maximum residue levels (MRLs) has also resulted in crop rejections. The economic impact of SWD has been particularly severe for organic operations, mainly due to the limited availability of effective insecticides. Integrated pest management (IPM) o...

Research paper thumbnail of DROP: Molecular voucher database for identification of Drosophila parasitoids

Molecular Ecology Resources

Research paper thumbnail of Optimizing Parasitoid and Host Densities for Efficient Rearing of Ontsira mellipes (Hymenoptera: Braconidae) on Asian Longhorned Beetle (Coleoptera: Cerambycidae)

Environmental Entomology

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is n... more Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). This study aimed to develop an efficient rearing system for this parasitoid, as a potential novel association biocontrol agent for the beetle, by investigating the effects of different densities of host (two, three, or four larvae) and parasitoid (one, two, three, four, five, six, seven, and eight female wasps) on Ontsira’s parasitization efficiency and reproductive outcomes. Results showed that overall parasitism and total numbers of parasitized hosts or progeny produced increased with host and/or parasitoid densities, but the number of parasitized hosts or progeny produced per female parasitoid decreased with parasitoid density at each given host density. Nonlinear regression indicated a consistent pattern of mutual interference as parasitoid density increased. Addi...

Research paper thumbnail of Reproductive Traits of Ontsira mellipes (Hymenoptera: Braconidae), a North American Parasitoid, as a Novel Biological Control Agent for Exotic Anoplophora glabripennis (Coleoptera: Cerambycidae)

Journal of Economic Entomology

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids that is ... more Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids that is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). To evaluate the potential of the parasitoid as a novel association control agent for the pest beetle, this study investigated some key reproductive traits of the parasitoid, including egg maturation dynamics, and host size preference and suitability in association with the beetle. Results showed that female wasps emerged with a substantial portion (38%) of their lifetime complement of mature eggs and matured eggs rapidly, reaching a peak 4–6 d post-eclosion. The number of mature eggs was positively related to the female wasp’s body size. Oviposition prompted production of more mature eggs by young female wasps. The parasitoid did not show a significant preference for large over small hosts in a choice test. Host size did not affect the parasitoid’s offspring survival...

Research paper thumbnail of Host preference of three Asian larval parasitoids to closely related Drosophila species: implications for biological control of Drosophila suzukii

Research paper thumbnail of Current Distribution of the Olive Psyllid, Euphyllura olivina, in California and Initial Evaluation of the Mediterranean Parasitoid Psyllaephagus euphyllurae as a Biological Control Candidate

Insects

The olive psyllid, Euphyllura olivina, is a newly invasive species to California with the potenti... more The olive psyllid, Euphyllura olivina, is a newly invasive species to California with the potential to become an economical pest if it reaches the olive production regions of California’s Central Valley. Here, we report on surveys undertaken in California to assess the psyllid’s current distribution and the occurrence of parasitism. Additionally, we present results of foreign collections of its parasitoids and initial non-target studies of a possible biological control agent, the Mediterranean parasitoid Psyllaephagus euphyllurae. The current distribution of the psyllid appears to be limited to the California coast between Monterey and San Diego; there have been no reports of infestations on olives in the major production areas of central and northern California. Psyllaephagus euphyllurae was the major primary parasitoid found in our foreign collections. The potential non-target impact of P. euphyllurae was tested on three native North American psyllid species: Neophyllura arctostap...

Research paper thumbnail of Temporal Dynamics of Host Use by Drosophila suzukii in California’s San Joaquin Valley: Implications for Area-Wide Pest Management

Insects

A major challenge to the area-wide management of Drosophila suzukii is understanding the fly’s ho... more A major challenge to the area-wide management of Drosophila suzukii is understanding the fly’s host use and temporal dynamics, which may dictate local movement patterns. We determined D. suzukii’s seasonal host use in California’s San Joaquin Valley by sampling common crop and non-crop fruits in a temporal sequence of fruit ripening. We then evaluated the suitability of selected fruits as hosts. Drosophila suzukii emerged from both intact and damaged cherries during the cooler, early season period. Fly density remained low through the hot spring–summer period and re-surged as temperatures lowered in fall when the fly did not cause damage to intact peach, nectarine, plum, pear, grape, pomegranate, apple, persimmon and citrus (in order of ripening) but did emerge from the damaged fruits of these crops. The fly also emerged from two ornamental fruits (loquats and cactus) but was not found on wild plum and two endemic wild fruits (buckthorn and bitter berry). Drosophila suzukii complete...

Research paper thumbnail of Comparison of thermal performances of two Asian larval parasitoids of Drosophila suzukii

Research paper thumbnail of ) Intra- and interspecific competition by Fopius arisanus and Diachasmimorpha tryoni (Hymenoptera: Braconidae), parasitoids of Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

Biological Control, 2003

Fopius arisanus (Sonan) and Diachasmimorpha tryoni (Cameron) are two important solitary endoparas... more Fopius arisanus (Sonan) and Diachasmimorpha tryoni (Cameron) are two important solitary endoparasitoids of tephritid fruit flies. The former species attacks host eggs while the latter attacks host larvae, and both species emerge as adults from the host puparium. This study investigated intrinsic competition between these two parasitoids, as well as aspects of intraspecific competition within each species in the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Parasitization by F. arisanus resulted in direct mortality of host eggs and prolonged development of host eggs and larvae. Superparasitism by F. arisanus was uncommon when mean parasitism per host patch was <50%, but increased with rising rates of parasitism. Superparasitism by D. tryoni was more common. In superparasitized hosts, supernumerary individuals of F. arisanus were killed through physiological suppression, while supernumerary larvae of D. tryoni were killed mainly through physical attack. In multiparasitized hosts, dissections showed that 81.6% of D. tryoni eggs in the presence of F. arisanus larvae died within 3 days, indicating physiological inhibition of egg hatch. Rearing results further showed that F. arisanus won almost all competitions against D. tryoni. The ratio of D. tryoni stings to ovipositions was lower in hosts not previously parasitized by F. arisanus than in parasitized hosts, suggesting that D. tryoni can discriminate against parasitized hosts. The mechanism that F. arisanus employs to eliminate D. tryoni is similar to that it uses against all other larval fruit fly parasitoids so far reported. The results are discussed in relation to the competitive superiority of early acting species in fruit fly parasitoids, and to a possible competitive-mediated mechanism underlying host shift by D. tryoni to attack nontarget flies following the successful introduction of F. arisanus in Hawaii.

Research paper thumbnail of Local and foreign field surveys of parasitoids of Drosophila suzukii

Research paper thumbnail of Functional and ovipositional responses of two pupal parasitoids of Drosophila suzukii

Research paper thumbnail of Diversity and biogeochemical function of planktonic fungi in the ocean

Progress in molecular and subcellular biology, 2012

Microbial communities play critical biogeochemical roles in the functioning of marine ecosystems.... more Microbial communities play critical biogeochemical roles in the functioning of marine ecosystems. Recent advances in molecular methods and environmental genomics have greatly advanced our understanding of microbial prokaryotes and their diversity and functional ecology in the world's oceans. Large populations of heterotrophic eukaryotes are well documented in the oceans and yet, their diversity and function remain relatively unknown. Particularly, large populations of planktonic fungi have long been known to exist in coastal and oceanic waters but the diversity and ecology of planktonic fungi remain one of the most under-studied microbial topics. Recent studies have revealed novel diversity and interesting ecological functions of planktonic fungi and suggest that they are a potentially important component in marine microbial food web. This chapter will review the diversity and ecology of planktonic fungi in the world's oceans and discuss their significance in ocean carbon an...

Research paper thumbnail of Host stage preference, efficacy and fecundity of parasitoids attacking Drosophila suzukii in newly invaded areas

Biological Control, 2015

ABSTRACT Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain ... more ABSTRACT Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain fruit crops in both North America and Europe. This may be due, in part, to the absence of specialized natural enemies that suppress population outbreaks. We performed a series of experiments under controlled laboratory conditions in tandem with a field study to evaluate the presence and efficacy of natural enemies associated with this pest in Italian and western United States fruit production regions. Our study involved one larval parasitoid, Leptopilina heterotoma (Thomson) (Hymenoptera: Figitidae), and two pupal parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae). Three indices were used to describe host-parasitoid interactions: degree of infestation (DI), success rate of parasitism (SP) and total encapsulation rate (TER). Results confirmed that each of these parasitoid species can develop on certain populations of the pest. In addition, host stage preferences of the tested parasitoid populations, developmental parameters and lifetime fecundity of North American P. vindemiae are provided. Results are discussed with respect to differences in potential utilization of D. suzukii among the tested parasitoid species and regional populations.

Research paper thumbnail of High Summer Temperatures Affect the Survival and Reproduction of Olive Fruit Fly (Diptera: Tephritidae)

Environmental Entomology, 2009

The olive fruit ßy, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is an invasive pest in Calif... more The olive fruit ßy, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is an invasive pest in California. Identifying environmental constraints that affect the geographic distribution and abundance of any invasive insect pest is fundamental to its effective management. CaliforniaÕs Central Valley, where most commercial olives are grown, is extremely hot during the summer, with maximum daily temperatures consistently Ͼ35.0ЊC. This study examined the effects of two diurnal temperature regimens (low 18.3ЊC, high 35.0 or 37.8ЊC) reßecting summer conditions in the valley, and one control temperature regimen (low 18.3ЊC, high 23.9ЊC) on the ßyÕs survival and reproductive success in the laboratory. The temperature regimen of 18.3Ð35.0ЊC resulted in delayed egg maturation and reduced production of mature eggs compared with the control temperature regimen. Egg maturation was possible at the higher temperature regimen when females were provided with water and food, and egg-laying occurred during the cold phase of the temperature cycle. Access to olive fruit and oviposition itself further promoted egg maturation. Under exposure to the 18.3Ð35.0ЊC temperature regimen, Ϸ50% of eggs died, and the remainder that hatched died as Þrst instars. No egg hatch occurred at the temperature treatment of 18.3Ð37.8ЊC. We conÞrmed these laboratory results through Þeld cage studies with adult B. oleae, conducted in the summer of 2007 and 2008. Under ambient summer temperatures, adult B. oleae survived for 1Ð2 wk, and females readily laid eggs when provided water and food. No offspring developed in midsummer of 2007, and Ͻ2% of the offspring developed to adults in summer 2008 trials. These results suggest that high summer temperatures limit the ßyÕs abundance in CaliforniaÕs Central Valley.

Research paper thumbnail of Psyttalia lounsburyi (Hymenoptera: Braconidae), potential biological control agent for the olive fruit fly in California

Biological Control, 2008

The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biol... more The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biological control program directed at the olive fruit fly, Bactrocera oleae (Rossi), in California, USA. Experimental assessment using three non-target species provided some ...

Research paper thumbnail of Effects of spinosad-based fruit fly bait GF-120 on tephritid fruit fly and aphid parasitoids

Biological Control, 2005

The spinosad-based fruit fly bait GF-120 has recently been developed as a primary tool for the ar... more The spinosad-based fruit fly bait GF-120 has recently been developed as a primary tool for the area-wide control and eradication of tephritid fruit flies. In this study, we assessed the direct contact toxicity of GF-120 to three major parasitoids of tephritids in Hawaii: Fopius arisanus (Sonan), Diachasmimorpha tryoni (Cameron), and Pysttalia fletcheri (Silvestri) (Hymenoptera: Braconidae), as well as one aphid parasitoid, Aphidius transcaspicus Telenga (Hymenoptera: Aphidiidae). All four parasitoid species were susceptible to GF-120. Males and females were equally susceptible to GF-120 for all species. The 24-h LC 50 values for the opiine braconid species were in a narrow range (8.3-17.5 ppm). The aphidiid appeared to be more susceptible than the opiines, probably due to the stickiness of GF-120. We confirmed that adult F. arisanus (as a model species) do not feed directly on GF-120 either in the presence or the absence of honey and water resources. F. arisanus tasted, discriminated, and gave up GF-120 droplets after a brief (<1 s) mouth examination. Mortality following exposure to GF-120 resulted from close contact. Furthermore, we found that when female F. arisanus were allowed to freely forage on host coffee branches sprayed with droplets at the recommended field rate for use of GF-120 (80 ppm), treatment mortality was significantly higher than control mortality (sprayed with water), and also increased with exposure time. Although GF-120 appears to be the most judicious of reduced-risk fruit fly baits currently available, our results suggest that area-wide application of GF-120 needs to be carefully monitored in situations where release or conservation of parasitoids is a prime concern.

Research paper thumbnail of Crop domestication relaxes both top-down and bottom-up effects on a specialist herbivore

Domestication of crop plants selects for numerous traits that often distinguish them dramatically... more Domestication of crop plants selects for numerous traits that often distinguish them dramatically from their wild progenitors. In some cases, these modifications lead to increased herbivory, by enhancing their attractiveness to herbivorous insects or reducing the efficiency of natural enemies, or both. This study investigated the effects of fruit enlargement on the olive (Olea europaea L.), the specialist olive fruit fly, Bactrocera oleae (Rossi), and its specialized larval parasitoids. Wild olive fruit are small (o2 mm pulp thickness) and the larval parasitoids associated with B. oleae have short ovipositors (o3 mm), while cultivated fruit are larger (4-8 mm pulp thickness). Female flies allocate more offspring to large than to small fruit within or across different-sized commercial cultivars, without reducing the fitness of their offspring. Fly larvae move deeper into the olive pulp with their increasing age and fruit size. In contrast, the specialist larval parasitoid, Psyttalia lounsburyi (Silvestri), more effectively parasitizes hosts in smaller than larger fruit. The inverse relationship between the performance of the fly and its co-evolved parasitoids on fruit of increasing sizes indicates that olive cultivation favors the success of the fly by providing a better food resource and more enemy-free space. These findings offer some explanation for the failure of the decades-old classical biological efforts to manage B. oleae using specialized larval parasitoids in the Mediterranean Basin and provide further evidence that crop domestication can alter host-parasitoid interactions.

Research paper thumbnail of High temperature affects olive fruit fly populations in California's Central Valley

California Agriculture, 2011

An adult female olive fruit fl y deposits an egg into olive fruit.

Research paper thumbnail of Psyttalia lounsburyi (Hymenoptera: Braconidae), potential biological control agent for the olive fruit fly in California

Biological Control, 2008

The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biol... more The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biological control program directed at the olive fruit fly, Bactrocera oleae (Rossi), in California, USA. Experimental assessment using three non-target species provided some evidence that P. lounsburyi restricts its host use to B. oleae. Female P. lounsburyi preferentially searched olives infested with mature thirdinstar B. oleae, over other non-target plants, but most offspring were reared from olives containing younger (second through young third instar) B. oleae larvae. Developmental time (egg to adult) and adult longevity were significantly affected by temperature and sex, with males tending to develop faster and females living longer, especially in the lower ranges of temperatures tested. The mean longevity of adult female P. lounsburyi was greatest when honey was available and lowest when they were provided water alone or nothing. The presence of hosts significantly decreased longevity. Females produced an average of 10.2 ± 2.6 progeny during their lifetimes, which was lower than expected for a parasitoid adapted to B. oleae and may be a consequence of increased fruit size-the result of cultivation and selection-reducing parasitoid effectiveness on cultivated vs. wild fruit, as well as constraints on oviposition behavior imposed by experimental design. The results are discussed with respect to the use of P. lounsburyi as a biological control agent for olive fruit fly in California. Published by Elsevier Inc.

Research paper thumbnail of Optimal Conditions for Diapause Survival of Aprostocetus fukutai, an Egg Parasitoid for Biological Control of Anoplophora chinensis

Insects

Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora c... more Aprostocetus fukutai is a specialist egg parasitoid of the citrus longhorned beetle Anoplophora chinensis, a high-risk invasive pest of hardwood trees. The parasitoid overwinters as diapausing mature larvae within the host egg and emerges in early summer in synchrony with the egg-laying peak of A. chinensis. This study investigated the parasitoid’s diapause survival in parasitized host eggs that either remained in potted trees under semi-natural conditions in southern France or were removed from the wood and held at four different humidities (44, 75, 85–93 and 100% RH) at 11 °C or four different temperature regimes (2, 5, 10 and 12.5 °C) at 100% RH in the laboratory. The temperature regimes reflect overwintering temperatures across the parasitoid’s geographical distribution in its native range. Results show that the parasitoid resumed its development to the adult stage at normal rearing conditions (22 °C, 100% RH, 14L:10D) after 6- or 7-months cold chilling at both the semi-natural ...

Research paper thumbnail of Drosophila suzukii (Diptera: Drosophilidae): A Decade of Research Towards a Sustainable Integrated Pest Management Program

Journal of Economic Entomology

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as spotted-wing drosophila (SW... more Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) also known as spotted-wing drosophila (SWD), is a pest native to Southeast Asia. In the last few decades, the pest has expanded its range to affect all major European and American fruit production regions. SWD is a highly adaptive insect that is able to disperse, survive, and flourish under a range of environmental conditions. Infestation by SWD generates both direct and indirect economic impacts through yield losses, shorter shelf life of infested fruit, and increased production costs. Fresh markets, frozen berries, and fruit export programs have been impacted by the pest due to zero tolerance for fruit infestation. As SWD control programs rely heavily on insecticides, exceedance of maximum residue levels (MRLs) has also resulted in crop rejections. The economic impact of SWD has been particularly severe for organic operations, mainly due to the limited availability of effective insecticides. Integrated pest management (IPM) o...

Research paper thumbnail of DROP: Molecular voucher database for identification of Drosophila parasitoids

Molecular Ecology Resources

Research paper thumbnail of Optimizing Parasitoid and Host Densities for Efficient Rearing of Ontsira mellipes (Hymenoptera: Braconidae) on Asian Longhorned Beetle (Coleoptera: Cerambycidae)

Environmental Entomology

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is n... more Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). This study aimed to develop an efficient rearing system for this parasitoid, as a potential novel association biocontrol agent for the beetle, by investigating the effects of different densities of host (two, three, or four larvae) and parasitoid (one, two, three, four, five, six, seven, and eight female wasps) on Ontsira’s parasitization efficiency and reproductive outcomes. Results showed that overall parasitism and total numbers of parasitized hosts or progeny produced increased with host and/or parasitoid densities, but the number of parasitized hosts or progeny produced per female parasitoid decreased with parasitoid density at each given host density. Nonlinear regression indicated a consistent pattern of mutual interference as parasitoid density increased. Addi...

Research paper thumbnail of Reproductive Traits of Ontsira mellipes (Hymenoptera: Braconidae), a North American Parasitoid, as a Novel Biological Control Agent for Exotic Anoplophora glabripennis (Coleoptera: Cerambycidae)

Journal of Economic Entomology

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids that is ... more Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids that is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). To evaluate the potential of the parasitoid as a novel association control agent for the pest beetle, this study investigated some key reproductive traits of the parasitoid, including egg maturation dynamics, and host size preference and suitability in association with the beetle. Results showed that female wasps emerged with a substantial portion (38%) of their lifetime complement of mature eggs and matured eggs rapidly, reaching a peak 4–6 d post-eclosion. The number of mature eggs was positively related to the female wasp’s body size. Oviposition prompted production of more mature eggs by young female wasps. The parasitoid did not show a significant preference for large over small hosts in a choice test. Host size did not affect the parasitoid’s offspring survival...

Research paper thumbnail of Host preference of three Asian larval parasitoids to closely related Drosophila species: implications for biological control of Drosophila suzukii

Research paper thumbnail of Current Distribution of the Olive Psyllid, Euphyllura olivina, in California and Initial Evaluation of the Mediterranean Parasitoid Psyllaephagus euphyllurae as a Biological Control Candidate

Insects

The olive psyllid, Euphyllura olivina, is a newly invasive species to California with the potenti... more The olive psyllid, Euphyllura olivina, is a newly invasive species to California with the potential to become an economical pest if it reaches the olive production regions of California’s Central Valley. Here, we report on surveys undertaken in California to assess the psyllid’s current distribution and the occurrence of parasitism. Additionally, we present results of foreign collections of its parasitoids and initial non-target studies of a possible biological control agent, the Mediterranean parasitoid Psyllaephagus euphyllurae. The current distribution of the psyllid appears to be limited to the California coast between Monterey and San Diego; there have been no reports of infestations on olives in the major production areas of central and northern California. Psyllaephagus euphyllurae was the major primary parasitoid found in our foreign collections. The potential non-target impact of P. euphyllurae was tested on three native North American psyllid species: Neophyllura arctostap...

Research paper thumbnail of Temporal Dynamics of Host Use by Drosophila suzukii in California’s San Joaquin Valley: Implications for Area-Wide Pest Management

Insects

A major challenge to the area-wide management of Drosophila suzukii is understanding the fly’s ho... more A major challenge to the area-wide management of Drosophila suzukii is understanding the fly’s host use and temporal dynamics, which may dictate local movement patterns. We determined D. suzukii’s seasonal host use in California’s San Joaquin Valley by sampling common crop and non-crop fruits in a temporal sequence of fruit ripening. We then evaluated the suitability of selected fruits as hosts. Drosophila suzukii emerged from both intact and damaged cherries during the cooler, early season period. Fly density remained low through the hot spring–summer period and re-surged as temperatures lowered in fall when the fly did not cause damage to intact peach, nectarine, plum, pear, grape, pomegranate, apple, persimmon and citrus (in order of ripening) but did emerge from the damaged fruits of these crops. The fly also emerged from two ornamental fruits (loquats and cactus) but was not found on wild plum and two endemic wild fruits (buckthorn and bitter berry). Drosophila suzukii complete...

Research paper thumbnail of Comparison of thermal performances of two Asian larval parasitoids of Drosophila suzukii

Research paper thumbnail of ) Intra- and interspecific competition by Fopius arisanus and Diachasmimorpha tryoni (Hymenoptera: Braconidae), parasitoids of Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

Biological Control, 2003

Fopius arisanus (Sonan) and Diachasmimorpha tryoni (Cameron) are two important solitary endoparas... more Fopius arisanus (Sonan) and Diachasmimorpha tryoni (Cameron) are two important solitary endoparasitoids of tephritid fruit flies. The former species attacks host eggs while the latter attacks host larvae, and both species emerge as adults from the host puparium. This study investigated intrinsic competition between these two parasitoids, as well as aspects of intraspecific competition within each species in the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Parasitization by F. arisanus resulted in direct mortality of host eggs and prolonged development of host eggs and larvae. Superparasitism by F. arisanus was uncommon when mean parasitism per host patch was <50%, but increased with rising rates of parasitism. Superparasitism by D. tryoni was more common. In superparasitized hosts, supernumerary individuals of F. arisanus were killed through physiological suppression, while supernumerary larvae of D. tryoni were killed mainly through physical attack. In multiparasitized hosts, dissections showed that 81.6% of D. tryoni eggs in the presence of F. arisanus larvae died within 3 days, indicating physiological inhibition of egg hatch. Rearing results further showed that F. arisanus won almost all competitions against D. tryoni. The ratio of D. tryoni stings to ovipositions was lower in hosts not previously parasitized by F. arisanus than in parasitized hosts, suggesting that D. tryoni can discriminate against parasitized hosts. The mechanism that F. arisanus employs to eliminate D. tryoni is similar to that it uses against all other larval fruit fly parasitoids so far reported. The results are discussed in relation to the competitive superiority of early acting species in fruit fly parasitoids, and to a possible competitive-mediated mechanism underlying host shift by D. tryoni to attack nontarget flies following the successful introduction of F. arisanus in Hawaii.

Research paper thumbnail of Local and foreign field surveys of parasitoids of Drosophila suzukii

Research paper thumbnail of Functional and ovipositional responses of two pupal parasitoids of Drosophila suzukii

Research paper thumbnail of Diversity and biogeochemical function of planktonic fungi in the ocean

Progress in molecular and subcellular biology, 2012

Microbial communities play critical biogeochemical roles in the functioning of marine ecosystems.... more Microbial communities play critical biogeochemical roles in the functioning of marine ecosystems. Recent advances in molecular methods and environmental genomics have greatly advanced our understanding of microbial prokaryotes and their diversity and functional ecology in the world's oceans. Large populations of heterotrophic eukaryotes are well documented in the oceans and yet, their diversity and function remain relatively unknown. Particularly, large populations of planktonic fungi have long been known to exist in coastal and oceanic waters but the diversity and ecology of planktonic fungi remain one of the most under-studied microbial topics. Recent studies have revealed novel diversity and interesting ecological functions of planktonic fungi and suggest that they are a potentially important component in marine microbial food web. This chapter will review the diversity and ecology of planktonic fungi in the world's oceans and discuss their significance in ocean carbon an...

Research paper thumbnail of Host stage preference, efficacy and fecundity of parasitoids attacking Drosophila suzukii in newly invaded areas

Biological Control, 2015

ABSTRACT Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain ... more ABSTRACT Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain fruit crops in both North America and Europe. This may be due, in part, to the absence of specialized natural enemies that suppress population outbreaks. We performed a series of experiments under controlled laboratory conditions in tandem with a field study to evaluate the presence and efficacy of natural enemies associated with this pest in Italian and western United States fruit production regions. Our study involved one larval parasitoid, Leptopilina heterotoma (Thomson) (Hymenoptera: Figitidae), and two pupal parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae). Three indices were used to describe host-parasitoid interactions: degree of infestation (DI), success rate of parasitism (SP) and total encapsulation rate (TER). Results confirmed that each of these parasitoid species can develop on certain populations of the pest. In addition, host stage preferences of the tested parasitoid populations, developmental parameters and lifetime fecundity of North American P. vindemiae are provided. Results are discussed with respect to differences in potential utilization of D. suzukii among the tested parasitoid species and regional populations.

Research paper thumbnail of High Summer Temperatures Affect the Survival and Reproduction of Olive Fruit Fly (Diptera: Tephritidae)

Environmental Entomology, 2009

The olive fruit ßy, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is an invasive pest in Calif... more The olive fruit ßy, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is an invasive pest in California. Identifying environmental constraints that affect the geographic distribution and abundance of any invasive insect pest is fundamental to its effective management. CaliforniaÕs Central Valley, where most commercial olives are grown, is extremely hot during the summer, with maximum daily temperatures consistently Ͼ35.0ЊC. This study examined the effects of two diurnal temperature regimens (low 18.3ЊC, high 35.0 or 37.8ЊC) reßecting summer conditions in the valley, and one control temperature regimen (low 18.3ЊC, high 23.9ЊC) on the ßyÕs survival and reproductive success in the laboratory. The temperature regimen of 18.3Ð35.0ЊC resulted in delayed egg maturation and reduced production of mature eggs compared with the control temperature regimen. Egg maturation was possible at the higher temperature regimen when females were provided with water and food, and egg-laying occurred during the cold phase of the temperature cycle. Access to olive fruit and oviposition itself further promoted egg maturation. Under exposure to the 18.3Ð35.0ЊC temperature regimen, Ϸ50% of eggs died, and the remainder that hatched died as Þrst instars. No egg hatch occurred at the temperature treatment of 18.3Ð37.8ЊC. We conÞrmed these laboratory results through Þeld cage studies with adult B. oleae, conducted in the summer of 2007 and 2008. Under ambient summer temperatures, adult B. oleae survived for 1Ð2 wk, and females readily laid eggs when provided water and food. No offspring developed in midsummer of 2007, and Ͻ2% of the offspring developed to adults in summer 2008 trials. These results suggest that high summer temperatures limit the ßyÕs abundance in CaliforniaÕs Central Valley.

Research paper thumbnail of Psyttalia lounsburyi (Hymenoptera: Braconidae), potential biological control agent for the olive fruit fly in California

Biological Control, 2008

The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biol... more The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biological control program directed at the olive fruit fly, Bactrocera oleae (Rossi), in California, USA. Experimental assessment using three non-target species provided some ...

Research paper thumbnail of Effects of spinosad-based fruit fly bait GF-120 on tephritid fruit fly and aphid parasitoids

Biological Control, 2005

The spinosad-based fruit fly bait GF-120 has recently been developed as a primary tool for the ar... more The spinosad-based fruit fly bait GF-120 has recently been developed as a primary tool for the area-wide control and eradication of tephritid fruit flies. In this study, we assessed the direct contact toxicity of GF-120 to three major parasitoids of tephritids in Hawaii: Fopius arisanus (Sonan), Diachasmimorpha tryoni (Cameron), and Pysttalia fletcheri (Silvestri) (Hymenoptera: Braconidae), as well as one aphid parasitoid, Aphidius transcaspicus Telenga (Hymenoptera: Aphidiidae). All four parasitoid species were susceptible to GF-120. Males and females were equally susceptible to GF-120 for all species. The 24-h LC 50 values for the opiine braconid species were in a narrow range (8.3-17.5 ppm). The aphidiid appeared to be more susceptible than the opiines, probably due to the stickiness of GF-120. We confirmed that adult F. arisanus (as a model species) do not feed directly on GF-120 either in the presence or the absence of honey and water resources. F. arisanus tasted, discriminated, and gave up GF-120 droplets after a brief (<1 s) mouth examination. Mortality following exposure to GF-120 resulted from close contact. Furthermore, we found that when female F. arisanus were allowed to freely forage on host coffee branches sprayed with droplets at the recommended field rate for use of GF-120 (80 ppm), treatment mortality was significantly higher than control mortality (sprayed with water), and also increased with exposure time. Although GF-120 appears to be the most judicious of reduced-risk fruit fly baits currently available, our results suggest that area-wide application of GF-120 needs to be carefully monitored in situations where release or conservation of parasitoids is a prime concern.

Research paper thumbnail of Crop domestication relaxes both top-down and bottom-up effects on a specialist herbivore

Domestication of crop plants selects for numerous traits that often distinguish them dramatically... more Domestication of crop plants selects for numerous traits that often distinguish them dramatically from their wild progenitors. In some cases, these modifications lead to increased herbivory, by enhancing their attractiveness to herbivorous insects or reducing the efficiency of natural enemies, or both. This study investigated the effects of fruit enlargement on the olive (Olea europaea L.), the specialist olive fruit fly, Bactrocera oleae (Rossi), and its specialized larval parasitoids. Wild olive fruit are small (o2 mm pulp thickness) and the larval parasitoids associated with B. oleae have short ovipositors (o3 mm), while cultivated fruit are larger (4-8 mm pulp thickness). Female flies allocate more offspring to large than to small fruit within or across different-sized commercial cultivars, without reducing the fitness of their offspring. Fly larvae move deeper into the olive pulp with their increasing age and fruit size. In contrast, the specialist larval parasitoid, Psyttalia lounsburyi (Silvestri), more effectively parasitizes hosts in smaller than larger fruit. The inverse relationship between the performance of the fly and its co-evolved parasitoids on fruit of increasing sizes indicates that olive cultivation favors the success of the fly by providing a better food resource and more enemy-free space. These findings offer some explanation for the failure of the decades-old classical biological efforts to manage B. oleae using specialized larval parasitoids in the Mediterranean Basin and provide further evidence that crop domestication can alter host-parasitoid interactions.

Research paper thumbnail of High temperature affects olive fruit fly populations in California's Central Valley

California Agriculture, 2011

An adult female olive fruit fl y deposits an egg into olive fruit.

Research paper thumbnail of Psyttalia lounsburyi (Hymenoptera: Braconidae), potential biological control agent for the olive fruit fly in California

Biological Control, 2008

The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biol... more The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biological control program directed at the olive fruit fly, Bactrocera oleae (Rossi), in California, USA. Experimental assessment using three non-target species provided some evidence that P. lounsburyi restricts its host use to B. oleae. Female P. lounsburyi preferentially searched olives infested with mature thirdinstar B. oleae, over other non-target plants, but most offspring were reared from olives containing younger (second through young third instar) B. oleae larvae. Developmental time (egg to adult) and adult longevity were significantly affected by temperature and sex, with males tending to develop faster and females living longer, especially in the lower ranges of temperatures tested. The mean longevity of adult female P. lounsburyi was greatest when honey was available and lowest when they were provided water alone or nothing. The presence of hosts significantly decreased longevity. Females produced an average of 10.2 ± 2.6 progeny during their lifetimes, which was lower than expected for a parasitoid adapted to B. oleae and may be a consequence of increased fruit size-the result of cultivation and selection-reducing parasitoid effectiveness on cultivated vs. wild fruit, as well as constraints on oviposition behavior imposed by experimental design. The results are discussed with respect to the use of P. lounsburyi as a biological control agent for olive fruit fly in California. Published by Elsevier Inc.