Sheila M. Fitzpatrick

Trapping Phyllophaga spp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

Abstract The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester. Resumen La feromona sexual del escarabajo, Phyllophaga anxia, es una mezcla de los ésteres metílicos de dos aminoácidos, L-valina y L-isoleucina. Se condujo un estudio de campo usando diferentes mezclas de los dos componentes en 59 sitios de Estados Unidos y Canada. Más de 57,000 machos de 61 especies dePhyllophaga fueron capturados e identificados. Tres de los resultados más importantes incluyen: (1) el extenso uso de los dos componentes [de las 147 especies de Phyllophaga (sensu stricto), en Estados Unidos y Canada, fueron capturados machos de cerca del 40% de ellas.]; (2) para la mayoría de las especies, la respuesta intraespecífica de los machos a las combinaciones de los dos aminoácidos fue consistente entre años diferentes, y en todos los sitios geográficos; y (3) un inusual polymorfismo de la feromona fue descrito para P. anxia. Poblaciones de algunos sitios fueron atrapados sólo con valina, mientras que poblaciones de otros sitios fueron atrapados sólo con isoleucina. También se encontraron sitios donde las poblaciones responden a ambos componentes, valina e isoleucina, produciendo una curva de captura bimodal. En el sureste del estado de Massachusetts y en Rhode Island, en Estados Unidos, machos de P. anxia fueron atrapados en trampas con mezclas de valina e isoleucina.

Host‐associated differentiation in reproductive behaviour of cecidomyiid midges on cranberry and blueberry

In British Columbia, Canada, Dasineura oxycoccana Johnson (Diptera: Cecidomyiidae) was initially found on highbush blueberry, Vaccinium corymbosum L. (Ericaceae) and has recently become a pest of cranberry, Vaccinium macrocarpon Aiton, a crop that is often found in close proximity with blueberry. Previous work has shown no temporal isolation and a potential for gene flow between these two D. oxycoccana populations. However, important behavioural differences were observed suggesting the potential for host races or cryptic species. Host races and cryptic species differ in their degree of assortative mating and reproductive isolation from partial to complete. We assessed whether populations of adult D. oxycoccana on these two crops would discriminate against mates from different natal hosts. Mating experiments were conducted within the greenhouse in 2010 using small glass vials without host plants present. Our results show D. oxycoccana from cranberry and blueberry hosts displayed complete assortative mating in the absence of their host plants. Behavioural data collected from the different crosses suggest these two D. oxycoccana populations differ in sex pheromones and close‐range ‘courtship pheromones’. We conclude that D. oxycoccana populations on cranberry and blueberry in British Columbia are reproductively isolated and probably represent cryptic species.

DNA Barcodes Suggest Cryptic Speciation in Dasineura oxycoccana (Diptera: Cecidomyiidae) on Cranberry, Vaccinium macrocarpon, and Blueberry, V. corymbosum

ABSTRACT Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) from cranberry Vaccinium macrocarpon is similar morphologically to D. oxycoccana from blueberry V. corymbosum, but a recent study revealed that individuals from cranberry do not mate with those from blueberry. To seek genetic differences between D. oxycoccana from cranberry (common name cranberry tipworm) and from blueberry (common name blueberry gall midge), we compared a 559-bp region of the mitochondrial cytochrome oxidase I (COI) gene from 65 individuals. Analysis of the COI sequences based on general time reversible with gamma distribution (GTRG) distance model revealed 10.7–13.1% divergence between cranberry tipworm and blueberry gall midge, whereas little divergence was observed within cranberry tipworm (0– 1.2%) or blueberry gall midge (0–1.3%) sequences. In neighbour-joining analysis, conducted for species identification, blueberry gall midge sequences generated in this study clustered with known D. oxycoccana sequences from National Council of Biotechnology (NCBI), but the cranberry tipworm sequences grouped into a separate cluster. To identify and discriminate cranberry tipworm and blueberry gall midge, we developed diagnostic PCR primers based on COI sequence differences. In a duplex PCR assay, these primers successfully discriminated D. oxycoccana originating from cranberry or blueberry. The concordance between data from our genetic studies and data from mating experiments by Cook et al. (2011) suggests cryptic speciation in D. oxycoccana populations on cranberry and blueberry.

Delayed mating reduces fecundity of blackheaded fireworm, Rhopobota naevana, on cranberry

This study examines the effects of delayed mating on two successive generations of blackheaded fireworm, Rhopobota naevana Hübner (Lepidoptera: Tortricidae), a pest of cranberry, Vaccinium macrocarpon Aiton (Ericaceae). The first (spring) generation produces eggs that hatch soon after oviposition, whereas the second (summer) generation produces mostly diapause eggs. Unmated female and male moths were placed together on the first, second, fourth, sixth, or eighth day after emergence. In the first generation, incidence of mating was greatest in the 1‐, 2‐, and 4‐day treatments then declined as female survival decreased. In the second generation, incidence of mating was lowest in the 1‐day treatment and greatest in the 2‐, 4‐, and 6‐day treatments. Most second generation females in the 6‐ and 8‐day treatments survived to mate. The mean oviposition period was 2.6 days for first generation females and 4.1 days for second generation females. Fecundity of singly mated females in both generations declined as age at mating advanced, but the pattern of decline differed between generations. First generation females that were mated on the first or second day laid more eggs than those mated on the fourth, sixth, or eighth day, and the number of infertile eggs increased as age at mating advanced. Fecundity of second generation females declined more gradually and the number of infertile eggs was greatest for females mated on the first, sixth, or eighth day. A consequence of the marked decline in fecundity due to mating delays in the first generation was that mean fecundity of the entire group of first generation females was ca. 13% less than that of the group of second generation females. On cranberry farms, pheromone‐mediated mating disruption can prevent or delay mating of blackheaded fireworm. If the frequency of disrupted (prevented and delayed) matings is similar in the two generations, fewer eggs will be laid in the first generation than in the second.

Age-specific titer and antennal perception of acetic acid, a component of malePseudaletia unipuncta (Haw.) hairpencil secretion.

Hairpencil secretion ofPseudaletia unipuncta (Haw.) contains acetic acid as well as previously identified benzaldehyde and benzyl alcohol. Age-specific titers of acetic acid were significantly greater than those of benzaldehyde and, at 25 °C, accumulation of both compounds in the hairpencils peaked on the second day after emergence. Excised antennae of males and females perceived both compounds. Antennal response to acetic acid did not vary significantly with age or sex, but male response to benzaldehyde was significantly greater than female response at all ages tested. Antennal response of both males and females to benzaldehyde tended to be greater on the fourth and eighth days after emergence than on the second.

Does rearing an aphid parasitoid on one host affect its ability to parasitize another species

Generalist parasitoids are commonly used for the biological control of insect pests; however, they are often reared on a single host species because this is more practical for commercial production. Few studies have investigated the consequences of rearing a generalist parasitoid on a single host species in terms of performance on other target pests. We investigated the impact of rearing the generalist parasitoid Praon unicum Smith (Hymenoptera: Braconidae, Aphidiinae) on an alternative aphid host Myzus persicae Sulzer (Hemiptera: Aphididae) with respect to its ability to perform on Ericaphis fimbriata Richards (Hemiptera: Aphididae), a pest of highbush blueberries. Parasitoids reared on the two aphid hosts did not differ in physical size measurements. Praon unicum reared on M. persicae had a lower oviposition success over 6 days compared with insects reared on E. fimbriata, mainly as a result of differences early in life. There was no difference in parasitoid egg size, lifetime fertility, age‐specific fertility, female offspring ratio, development time or calculated intrinsic rate of increase from the two aphid hosts. We conclude that there were no negative consequences of rearing P. unicum on M. persicae on its ability to parasitize E. fimbriata, although further field studies would need to be performed to investigate whether natal host influences parasitoid preference.

Phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) on Cranberry and Blueberry Indicates Potential for Gene Flow

ABSTRACT Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae) is a pest of cranberry, Vaccinium macrocarpon (Aiton) (Ericales: Ericaceae), and highbush blueberry, Vaccinium corymbosum (L.) (Ericales: Ericaceae), in North America. In British Columbia, Canada, D. oxycoccana was first found on highbush blueberry in 1991 and then on cranberry seven years later. Because many cranberry and highbush blueberry farms are adjacent to one another, we hypothesized that D. oxycoccana was moving from highbush blueberry onto cranberry. Cranberry and highbush blueberry differ in phenology, and adaptation to these different phenologies may result in host races or cryptic species on these two crops. We recognized the alternative hypothesis that D. oxycoccana had arrived as immature stages with cranberry vines imported from another region of North America. During spring and summer, we recorded the phenology of D. oxycoccana and the development of plant shoots from three cranberry and three highbush blueberry farms to determine whether the opportunity exists for successful movement of D. oxycoccana between the two crops. Our results show that D. oxycoccana from cranberry and highbush blueberry overlap in phenology for much of the season, indicating a high potential for movement and gene flow. However, differences were seen in number of larvae per shoot, location of pupae, and heat unit accumulation during larval development suggesting that instead there may be the potential for host race or cryptic species formation.