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The host-specific beetle Neogalerucella calmariensis was introduced to North America to control Lythrum salicaria, and in some areas has persisted in high population densities despite decimation of target plants. We hypothesised that egg predation might contribute to the survival of the beetles. In small-scale laboratory experiments, we investigated the likelihood of egg cannibalism at different N. calmariensis life stages. Neither neonates nor adults cannibalised eggs, however late instar larvae readily preyed on eggs of conspecifics. Pupal weights of larvae that cannibalised eggs were larger than those fed only leaf material suggesting that egg cannibalism may be associated with a fitness benefit. [ABSTRACT FROM AUTHOR]

We report the presence of two Asian species of larval parasitoids of spotted wing Drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), in northwestern North America. Leptopilina japonica Novkovic & Kimura and Ganaspis brasiliensis (Ihering) (Hymenoptera: Figitidae) were found foraging near and emerging from fruits infested by D. suzukii at several locations across coastal British Columbia, Canada in the summer and fall of 2019. While G. brasiliensis was found in British Columbia for the first time in 2019, re-inspection of previously collected specimens suggests that L. japonica has been present since at least 2016. Additionally, we found a species of Asobara associated with D. suzukii in British Columbia that is possibly Asobara rufescens (Förster) (known only from the Palearctic Region) based on COI DNA barcode data. These findings add to the list of cases documenting adventive establishment of candidate classical biological control agents outside of their native ranges. The findings also illustrate the need for revisiting species concepts within Asobara, as well as host and geographic distribution data due to cryptic and/or misidentified species. [ABSTRACT FROM AUTHOR]

• The Asiatic parasitoids Spathius galinae and Tetrastichus planipennisi have been released in North America to manage emerald ash borer. • Yellow pan trap captures of Spathius galinae and Tetrastichus planipennisi varied among sites and years, and occurred across a wide range of growing degree days. • Placing yellow pan traps on trees with suppressed or intermediate crown classes, abundant epicormics sprouts and smaller diameters increased T. planipennisi capture rates. • Tetrastichus planipennisi yellow pan trap captures had a positive relationship with parasitized EAB larval densities from the previous year. Yellow pan traps are frequently used to monitor establishment of hymenopteran parasitoids introduced for biological control of the invasive ash pest, emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). To evaluate and improve their efficacy as a monitoring tool, we conducted field studies during 2016–2019 in southern Michigan where the introduced hymenopteran larval parasitoids, Tetrastichus planipennisi Yang (Eulophidae) and Spathius galinae (Braconidae) Belokobylskij & Strazanac are established. Our objectives were to describe parasitoid seasonal abundance, identify host tree variables that might influence parasitoid capture numbers (i.e., number of adults captured) and capture rates (i.e., number of positive traps per collecting period), and compare parasitoid trap captures to parasitized EAB larval densities. Yellow pan trap capture numbers and rates of both species were low for most study sites and years. Captures of both parasitoid species occurred throughout the growing season and neither showed a consistent trend in seasonal abundance. Emerald ash borer infested trees with suppressed or intermediate crown classes had higher T. planipennisi capture numbers and rates than dominant or codominant crown classes. During some years, T. planipennisi capture rates increased with decreasing tree diameter at breast height (DBH) and T. planipennisi capture numbers increased with increasing numbers of epicormics sprouts on host trees. Spathius galinae captures had no significant relationship with host tree variables but low overall capture numbers, due to its more recent introduction, may have prevented detection of any relationships. Tetrastichus planipennisi adult capture numbers were positively related to previous year's densities of T. planipennisi parasitized larvae dissected from trees. Spathius galinae capture numbers were not correlated with parasitized EAB larval densities. We discuss the relevance of our findings to improve yellow pan trap efficacy for monitoring introduced EAB larval parasitoids. [ABSTRACT FROM AUTHOR]

The larval parasite Lathrolestes ensator Brauns (Hymenoptera: Ichneumonidae) has only one known host, Hoplocampa testudinea Klug (Hymenoptera: Tenthredinidae), a pest that attacks only one host: the apple tree. A classical biological program conducted from 1994 to 2001 successfully led to the establishment of L. ensator in Frelighsburg, QC, Canada. This paper reports on work conducted from 2002 to 2015 to disseminate L. ensator in eastern North America. Each year, fruitlets showing secondary damage of H. testudinea were collected in source orchards of Frelighsburg. Random samples of these fruitlets were dissected to estimate % parasitized larvae: the remaining fruitlets were used for releases in apple orchards located in Quebec, Ontario, Nova Scotia and New Hampshire. Collection of fruitlets with secondary damage in participating orchards showed that L. ensator successfully established in Quebec in Henryville, Saint-Hilaire, Magog and St-Georges de Windsor, and in Ontario in Hilton. L. ensator is the only known natural enemy of H. testudinea in North America. [ABSTRACT FROM AUTHOR]

Native to Japan, Fallopia japonica, most frequently referred to as Japanese knotweed, is a highly problematic invasive weed, particularly in the UK and North America. During surveys for natural enemies of this plant in Japan, two species of Mycosphaerella were collected. One of these was identified as M. polygoni-cuspidati, and is redescribed and neotypified. Causing a damaging leaf spot disease of F. japonica throughout its natural range in Japan, it is absent from the host’s exotic range. The restriction of M. polygoni-cuspidati to F. japonica in its center of origin, together with its severe impact on host fitness, indicates that this is a coevolved natural enemy with high potential as a classical biological control agent for the long-term management of this ecologically and economically important weed. In the field, the fungus has a reduced life cycle, with only spermogonia and pseudothecia (ascomata) being formed. Ascospores are the primary source of infection, and studies show that the mycelium from in vitro cultures is also infective and hyphae penetrate mainly via the stomata. A further, undescribed species of Mycosphaerella co-occurs with M. polygoni-cuspidati, here proposed as the new species M. shimabarensis. Both species have been studied using cultural, morphological and molecular phylogenetic methods. [ABSTRACT FROM AUTHOR]

The parasitoid Binodoxys communis (Gahan) (Hymenoptera: Braconidae) is a candidate for release against the Asian soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae), in North America. Using a series of Y-tube olfactometer assays, we recorded responses of naïve and experienced B. communis females to odors from both target and non-target host plant complexes. The non-target host plant complexes included three aphid species native to North America [ Aphis monardae Oestlund, Aphis oestlundi Gillette, and Aphis asclepiadis (Fitch)] and one species presumed to be exotic to North America ( Aphis nerii Boyer de Fonscolombe), all on their respective host plants. We also investigated whether the parasitoid distinguishes between volatiles from soybean infested with A. glycines vs. those of uninfested plants. Volatiles from A. glycines-infested soybean plants and several non-target host plant complexes elicited a response in B. communis, which seemed to be reinforced through oviposition experience. Wasps with experience on a specific host plant complex increased their response to odors of this complex. Neither naïve nor experienced wasps, however, preferred odors from target vs. non-target host plant complexes in choice tests. Our data also indicate that B. communis is unable to distinguish between volatiles from infested vs. uninfested soybean plants. This study shows that B. communis females respond to a broad array of olfactory stimuli, exhibit low fidelity for any particular odor, and employ some behavioral plasticity in their response to volatile cues. We discuss implications of these results for establishment of B. communis and potential undesirable non-target effects associated with the release of this species in North America. [ABSTRACT FROM AUTHOR]

Cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Col., Curculionidae), is an invasive alien pest that is spreading in North America. To aid with planning for introductions of European parasitoids in North America, we examined the status of the only classical biological control release against this pest in North America, which in 1949 introduced Mesopolobus morys, Stenomalina gracilis and Trichomalus perfectus (Hym., Pteromalidae). Weevils and parasitoids were reared in 2005 from mass collections of seedpods of Brassica napus, Brassica rapa and Raphanus raphanistrum (Brassicaceae) from 18 sites in the Fraser Valley, near Vancouver, British Columbia, Canada. Of the three European parasitoid species that were originally released, only S. gracilis was found. The predominant hymenopterous parasitoid species were Trichomalus lucidus, S. gracilis, Mesopolobus moryoides (Pteromalidae), Necremnus tidius (Eulophidae) and Eupelmus vesicularis (Eupelmidae). These constituted over 97% of the parasitoids reared, although overall parasitism was low. Only M. moryoides is clearly North American in distribution; other than S. gracilis, the remaining species were either accidentally introduced or are Holarctic in distribution. Based on these results, re-releases of M. morys and T. perfectus in North America should be considered as part of a classical biological control programme. However, redistribution of S. gracilis is not recommended at present because of potential conflicts with biological control programmes against weeds. Ongoing re-examination of classical biological control programmes can further our understanding of failure of release programmes, particularly when re-examination can be made in the light of improved taxonomy and systematics of the target and agent species. [ABSTRACT FROM AUTHOR]

Classical biological control of insect pests and weeds may lead to potential conflicts, where insect pests are closely related to weed biological control agents. Such a conflict may occur in the classical biological control of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) in North America, which belongs to the same subfamily, Ceutorhynchinae, as a number of agents introduced or proposed for introduction against non-indigenous invasive weed species. We propose a step-by-step procedure to select non-target species and thereby to develop a non-target species test list for screening candidate entomophagous biological control agents of a herbivore pest insect in a way that would simultaneously evaluate non-target potential on weed biological control agents and other non-target species. Using these recommendations, we developed a non-target test list for host specificity evaluations in the area of origin (Europe) and the area of introduction (North America) for cabbage seedpod weevil parasitoids. Scientifically based predictions on expected host–parasitoid interactions and ecological information about the ecological host range in the area of origin can help avoid conflicts, while still allowing the introduction of safe and effective agents against both insect pests and weeds. [ABSTRACT FROM AUTHOR]

The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is an invasive species in North America where it threatens Opuntia native populations. The insect is expanding its distribution along the United States Gulf Coast. In the search for alternative strategies to reduce its impact, the introduction of a natural enemy, Apanteles opuntiarum Martínez and Berta (Hymenoptera: Braconidae), is being pursued as a biological control option. To identify promising areas to intentionally introduce A. opuntiarum for the control of C. cactorum, we estimated the overlap of fundamental ecological niches of the two species to predict their common geographic distributions using the BAM diagram. Models were based on native distributional data for both species, 19 bioclimatic variables, and the Maxent algorithm to calculate the environmental suitability of both species in North America. The environmental suitability of C. cactorum in North America was projected from Florida to Texas (United States) along the Gulf coastal areas, reaching Mexico in northern regions. Apanteles opuntiarum environmental suitability showed a substantial similarity with the calculations for C. cactorum in the United States. Intentional introductions of A. opuntiarum in the actual distribution areas of the cactus moth are predicted to be successful; A. opuntiarum will find its host in an environment conducive to its survival and dispersal. [ABSTRACT FROM AUTHOR]

• We examined modulation of diapause induction and termination in O. agrili , a parasitoid of emerald ash borer. • Photoperiod-induced diapause is modulated in developing O. agrili larvae and the mother's photoperiod exposure does not affect diapause of progeny. • The critical day length for photoperiod-induced diapause is between 14.25 and 14.5 h. • Photoperiod-induced diapause can be terminated by increasing day length above the critical day length. • Critical day length may affect O. agrili population dynamics along a latitudinal gradient. Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) is a solitary and parthenogenetic egg parasitoid from China being introduced into North America (NA) as a biological control agent of the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an extremely invasive and destructive pest of ash trees (Fraxinus spp.). Oobius agrili is being released over a broad geographical range in NA where photoperiod varies considerably during the season of parasitoid-host activity. We conducted laboratory studies to determine 1) if photoperiod-induced diapause is modulated maternally, grand-maternally, and/or directly in immature parasitoids; 2) interactions of maternal adult age and photoperiod exposure on diapause induction; 3) the critical day length for diapause induction; 4) the critical age at which photoperiod-induced diapause is modulated in developing larvae; 5) the effects of photoperiod and length of chill on diapause termination; and, 6) the effects of photoperiod on O. agrili biology across a latitudinal gradient. We found that photoperiod exposure of O. agrili larvae developing inside host eggs directly induced diapause, and maternal or grand-maternal photoperiod treatments did not affect diapause induction in their progeny. However, older adults that experienced diapause as larvae produced more progeny that entered diapause when their progeny were exposed to short-day photoperiods. All progeny produced by adults that developed from nondiapaused larvae entered diapause when exposed to short-day photoperiods. Diapause response to photoperiod declined dramatically after larvae were 6–7 days old. The critical day length for diapause induction was between 14.25 and 14.5 h of daylight (at 25 °C). Photoperiod and duration of chill affected diapause termination of diapausing O. agrili larvae. The cumulative number of degree days (base 10 °C) required for adult emergence was highest for the combination of 12 h light:12 h dark (12L:12D) photoperiod combined with the shortest chill period, and lowest for 14.5L:9.5D and 16L:8D combined with the longest chill period. We discuss the effects of photoperiod on parasitoid-host synchrony, population dynamics, and fitness of O. agrili across the geographical area where it is being released. [ABSTRACT FROM AUTHOR]