Infestation Of Buds Research Articles

Biophysical and Morphological Basis of Resistance against Linseed (Linum usitatissimum L.) Bud fly (Dasyneura lini Barnes)

A field experiment was conducted at the research cum instructional farm, College of Agriculture, Nagpur, Dr. PDKV, Maharashtra during rabi 2021-22 with the objective to find the biophysical and morphological basis of resistance against linseed bud fly (Dasyneura lini Barnes). A set of 36 germplasm was sown in RBD in paired rows of 2 m and a spacing of 45 cm x 10 cm. The results indicated that resistant germplasm against bud fly IC498428 and Jawahar-17 had relatively higher sepal thickness (21.18 and 19.64 μ) as well as lower average infestation recorded (8.19 and 9.75%) while susceptible germplasm IC413173 (49.12%), IC498783 (42.70%), IC498924 (42.48%) and EC011748 (45.00%) exhibited minimum sepal thickness (6.90, 9.28, 9.32 and 8.33 μ, respectively). The character association studies showed a highly significant negative correlation (r = -0.852**) between the thickness of sepals and the percentage of bud fly infestation. The correlation between plant height and bud infestation was negative (-0.042) and non-significant

Screening of Cowpea Genotypes for Field Resistance to the Spotted Pod Borer (Maruca vitrata)

Background: Cowpea [Vigna unguiculata (L.) Walp.] is an important legume crop known for its nutritional value. However, the cultivation of this crop is greatly hampered by a destructive pest, a spotted pod borer (Maruca vitrata Fab.). Keeping the caustic nature of the pest in view, the present study was undertaken. Methods: Field evaluation of thirty cowpea genotypes was carried out by raising cowpea plants in an open field. Observations on the M. vitrata incidence were recorded at three days’ intervals starting from the development of the first buds to the end of flowering. Based on the level of infestation of buds, flowers and pods, the cowpea genotypes were categorised into four groups viz., resistant, moderately resistant, susceptible and highly susceptible. Results: Results of the study revealed a significant variation between the genotypes in terms of total damage (0.21 to 48.46%). Genotype IC 2918 recorded remarkably low damaged (0.12%) and was on par with Palakkadan thandan payar, Hridya, EC 300039, EC 101216, EC 98668, IC 39945, IC 52110, IC 39922 and IC 39916. The genotype Bhagyalaxmi recorded the highest damage (48.46%) followed by the variety Lola (30.04%). Flower buds were more susceptible to M. vitrata and suffered severe damage as compared to flowers and pods. Conversely, genotypes EC 98668 and IC 39922 were free from bud damage. Genotypes EC 300039, EC 98668, IC 52110, IC 39945, IC 2918 and IC 39922 recorded no flower damage and Palakkadan thandan payar, IC 39945, IC 2918 and IC 39947 recorded no pod damage.

Resistance of Pinus Sibirica clones to insect conobionts in the Yelbashinsky nursery of JSC «Berdsky forestry» in Novosibirsk region

The inter-clonal variability of Siberian cedar in resistance to insect conobionts was studied. The authors revealed that the main pests of cones and seeds are cone moth Dioryctria abietella Schiff and giant cone moth Eupithecia abietaria Goeze in the archives of plus-tree clones of Novosibirsk region (Yelbashinsky Nursery of JSC «Berdsky forestry», Iskitimsky district). The moth’s infestation of buds was 23.4%, and the infestation of buds by the moth was 2.0%. Selection of cedar for resistance to cone moths can be an effective way to increase yield at breeding and seed production facilities of this breed based on the study of inter-clonal variability in the degree of cone moth damage and other traits. Selection for resistance to cone moth disease will not significantly change stem wood produc- tivity due to the absence of a reliable interclonal correlation between the degree of cone damage and tree size. The authors described the result of the findings of the inter-clone correlation, consisting of a significant positive correlation between cone size and «granularity» and stem height and diameter. This result was against the background of the complete absence of any correlation between cone damage by conobionts and tree and cone size. The authors also concluded that selection for stem wood productivity in cedar would be accompanied by an increase in cone size and «granularity» (and vice versa), while selection for resistance to conobionts will not lead to significant changes in other vegetative and generative traits.

Buds, Bugs and Bienniality: The Floral Biology of Eschweilera tenuifolia (O. Berg) Miers in a Black-Water Flooded Forest, Central Amazonia

Research Highlights: Our study establishes the biennial nature of flowering intensity as a life-time energy-conserving strategy; we show unexpectedly high flower:fruit ratios despite extensive predation of buds and flowers by insect larvae; ‘selective’ bud abortion may be a key annual energy-saving strategy. Background and Objectives: We aim to explain the strongly biennial flowering pattern of Eschweilera tenuifolia, an ecologically key tree species of Amazon blackwater-flooded forest, inundated for up to nine months annually, and with large flowers (6 cm in width). Materials and Methods: We quantified the insect infestation of central Amazonian Eschweilera tenuifolia buds and flowers; we measured nectar production from flower opening onwards, examined flower duration and monitored pollen theft. We tested the role of infestation in bud abortion, nectar production and fruit production initiation. Results: Our study shows extensive predation of buds and flowers by insect larvae, as well as selective abortion of heavily infested buds, and limited loss to pollen thieves which fed largely on infertile fodder pollen. Nectar production peaked in the morning, with no nocturnal nectar production recorded. Sucrose levels were similar to congeneric values (mean 37.4%), and near-constant during production. Flower duration (4–5 days) was longer than reported for other congenerics. Conclusions: Insect infestation of buds can play an important role in regulating flower:fruit ratios, thus setting limits on individual total seed set. Individual Eschweilera tenuifolia appear to invest highly in reproduction every second year. Extended flower duration may be a strategy to enhance pollination success, but increases overall reproductive investment. Abortion of heavily infested buds may minimize allocation of energy to malformed flowers, which have a lower chance of attracting pollinators, thus functioning as a short-term energy-saving strategy. Additionally, biennial flowering in E. tenuifolia is likely to be an energy-conserving response in a highly physiologically-challenging environment. Thus, E. tenuifolia exhibits energy-conservation strategies at two divergent temporal scales.

Morphological characteristics basis of resistance in Linseed (Linum usitatissimum L.) for bud fly (Dasyneura lini Barnes) in Central Uttar Pradesh

A field experiment conducted for screened 288 elite gen pool of linseed against bud fly infestation at Kanpur, India during rabi 2011-12 and 2012-13. The flowering duration showed significant positive relationship (r=0.9278 and 0.9368) with bud infestation. The maximum flowering duration 32.80 and 31.44 days was recorded on variety A-44 with highest bud infestation of 62.29 and 69.99 percent during respective years against variety C-C-1-2 which had a shortest flowering duration of 8.80 and 12.94 days with the minimum 16.38 and 14.30 percent bud fly infestation. The sepal thickness negative highly significant relationship (r=--0.7224) with bud infestation. The resistant germplasm line maximum sepal thickness (0.49 mm) had relative minimum bud infestation (6.88%) while minimum sepal thickness (0.24 mm) with maximum bud infestation(65.11%), plant height, flower colour did not show significance in bud fly resistance, whereas, flowering duration bud as well as sepal thickness showed significant impact.

Histological basis of resistance in Linseed against bud fly (Dasyneura lini Barnes) in Central Uttar Pradesh

A field experiment conducted for screened 288 germplasm of linseed against bud fly infestation at Kanpur, Uttar Pradesh during rabi season to study the historical basis of resistance of linseed against bud fly. The results indicated that the sepal thickness negative highly significant relationship (r=--0.7224) with bud infestation. The resistant germplasm line maximum sepal thickness (0.49 mm) had relative minimum bud infestation (6.88%) and was statically at par other resistant germplasm lines viz. A-95B, CI-1385, EC-1392, EC-1424, GS-234, IC-15888 and JRF-5. While minimum sepal thickness (0.24 mm) with maximum bud infestation (65.11%) which was statically at par with other susceptible lines viz. Ajgan-3-1, Ajgan-20M, Alipur (Hamirpur), Anand, GS-148, GS-440, Gunawal Local, NP (RR) 193, RAULD-7810, RLC-28 (PM), MS-14, SJKO-2, SJKO-45. The genotypes with minimum thickness of sepal suffered maximum bud infestation as compared to those with maximum sepal thickness.

Impact of flowering duration in linseed (Linum usitatissimum L.) resistance to the bud flies (Dasyneura lini Barnes) in Central Uttar Pradesh

A field experiment conducted for screened 288 elite gen pool of linseed against bud fly infestation at Kanpur, India during rabi 2011-12 and 2012-13. The flowering duration showed significant positive relationship (r=0.9278 and 0.9368) with bud infestation. The maximum flowering duration 32.80 and 31.44 days was recorded on variety A-44 with highest bud infestation of 62.29 and 69.99 percent during respective years against variety C-C-1-2 which had a shortest flowering duration of 8.80 and 12.94 days with the minimum 16.38 and 14.30 percent bud fly infestation. Categorization on the basis of flowering duration and damage caused by the bud fly, were found, flowering duration range (11.80- 18.30) and (12.94-21.44), number of entries 11 and 8 were resistant, (0-10 %), flowering duration range (11.80-20.80) and (11.44-25.94), number of entries, 164 and 146 moderately resistant, (10 to 25%), flowering duration range (12.80-30.80) and (11.44- 28.94), number of entries 98 and 116 moderately susceptible, (25 to 50%), flowering duration range (24.80-33.30) and (21.94-32.44), number of entries 15 and 18 susceptible, (50 to 75%), none of the varieties found highly susceptible (more than 75%) to be bud fly attack during 2011-12 and 2012-13, respectively. The variety having longer flowering duration was severely infested by bud fly as compared to those with shorter flowering duration.

Bud structure of linseed (Linum usitatissimum L.) in relation to incidence of bud fly (Dasyneura lini Barnes) in Central Uttar Pradesh

A field experiment conducted for screened 288 elite gen pool of linseed against bud fly infestation at Kanpur, India during rabi 2012-13 to study the bud structure of resistance of linseed against bud fly. The results indicated that the bud length and width showed significant positive correlation coefficient relationship (r=0.1559 and 0.0761) bud infestation. The resistant germplasm line minimum (GS-234) minimum bud length and width (7.93 ×3.26 mm) had relative minimum bud infestation (6.88%) and was statically at par other resistant germplasm lines viz. A-95B, CI-1385, EC-1392, EC-1424, GS-234, IC-15888 and JRF-5. While susceptible germplasm line (Arny) exhibited maximum bud length and width (8.25 ×3. 23 mm) maximum bud infestation(65.11%) which was statically at par with other susceptible lines viz. Ajgan-3-1, Ajgan-20M, Alipur (Hamirpur), Anand, GS-148, GS-440, Gunawal Local, NP(RR)193, RAULD-7810, RLC-28(PM), MS-14, SJKO-2, SJKO-45.

Impact of insecticides on oilseed rape bud infestation with eggs and larvae of pollen beetle (Brassicogethes aeneus (Fabricius))

One of the main insect pests in oilseed rape is the pollen beetle (Brassicogethes aeneus (Fabricius), syn. Meligethes aeneus). To maximize efficiency of control of this pest, insecticides are required that ideally, not just prevent yield losses by bud feeding of overwintered pollen beetles, but simultaneously minimize the reproduction of the pest, thereby reducing the size of the following generation infesting next year’s oilseed rape. The neonicotinoid active substance thiacloprid is known to reduce bud infestation with eggs and larvae. However, the mechanisms by which this occurs as well as the effects of other active substances are not known. In this study, the effects of the neonicotinoid insecticide Biscaya (a.i. thiacloprid) and the pyrethroids Mavrik (tau-fluvalinate) and Karate Zeon (lambda-cyhalothrin) applied at the bud stage of winter oilseed rape with recommended field rates on infestation of buds with eggs and larvae of pollen beetles were tested in field trials in Germany in 2013–2015. In additional greenhouse experiments, it was investigated whether effects on bud infestation were caused by lethal effects on pollen beetle or by insecticidal residues on plants causing sublethal effects. In the field trials, application of Biscaya and Mavrik significantly reduced the percentage of buds containing eggs and larvae in contrast to Karate Zeon. In 2014 and 2015, 14 days after application, bud infestation on the main raceme was reduced by 86 and 82%, respectively, in Biscaya-treated plots and by 51 and 71%, respectively, in Mavrik-treated plots compared to the untreated plots. In the greenhouse experiments, the lowest percentage of bud infestation with eggs and larvae was recorded on Biscaya-treated plants whereas on Mavrik-treated plants, there was no significant difference compared with the control. The results of the field trials show that Biscaya and Mavrik reduced oilseed rape bud infestation with eggs and larvae of pollen beetles primarily by lethal effects on overwintered pollen beetles or by repellency. However, Biscaya had additional effects on egg laying, which was supported by the greenhouse experiments.

Influence of Abiotic Factors on Pheromone Trap Catches and Field Infestation of Helicoverpa armigera on Carnation (Dianthus caryophyllus) in Hilly Region of West Bengal, India

An experiment was carried out at Regional Research Station, Uttar Banga Krishi Viswavidyalaya, Kalimpong, during the winter seasons of 2008–09 and 2009–10, to study the impact of weather factors on pheromone trap catches and field infestation of Helicoverpa armigera (Hubner) on carnation (Dianthus caryophyllus Linnaeus). Various abiotic parameters like maximum and minimum temperature, maximum and minimum relative humidity and rainfall registered low level of non-significant association with the trap catch data during both the seasons. The simple regression equations of pheromone trap catch data with the meteorological parameters indicated that the abiotic factors had non-significant influence on the trap catches of H. armigera moths. The maximum temperature and rainfall was responsible for the maximum 26.82 and 8.79% variation in the trap catch data during 2008–09 and 2009–10, respectively. The multiple regression analysis showed that the combined effect of all the meteorological parameters was also statistically non-significant, though 62.88 and 69.13% variation in trap catches was due to weather factors, during 2008–09 and 2009–10, respectively. The correlation coefficients (r) between the field infestation data (number of eggs and larvae plant−1, % bud infestation) and various meteorological parameters revealed that the ecological factors mostly registered non-significant correlation with the field incidence of the pest as well as with the actual infestation of buds and flowers of carnation. Only the minimum temperature was positively and significantly associated with the % bud infestation during both the years.

Inheritance of resistance to bud fly infestation in linseed (Linum usitatissimumL.)

Genetic analysis was carried out to determine the mode of inheritance of resistance to bud fly which is a key pest of linseed during flowering stage. Parents, F1, F2, BC1 and BC2 populations of three crosses involving two resistant, IC 15888 and JRF4 and two susceptible parents, viz., Neelum and GS-41 were the experimental materials. Reaction to bud fly in F1s of all the three crosses indicated that resistance was dominant over susceptibility. The F2 and back cross segregants were categorized in to resistant and susceptible classes based on per cent bud infestation. The genetic analysis in F2 generation revealed that two dominant complementary genes in IC 15888 control the bud fly resistance, while JRF 4 carried a single dominant gene for resistance. The F2 results were confirmed by genetic analysis of back cross populations. It can be categorically stated that the knowledge of number and nature of resistance genes in IC 15888 and JRF4 will be valuable for development of bud fly resistant varieties in linseed.

Reproductive ecology of Syzygium alternifolium (Myrtaceae), an endemic and endangered tropical tree species in the southern Eastern Ghats of India

Syzygium alternifolium is a semi-evergreen mass-flowering tree species of dry deciduous forest in the southern Eastern Ghats of India. It is a mass bloomer with flowering during dry season. The floral traits suggest a mixed pollination syndrome involving entomophily and anemophily together called as ambophily. Further, the floral traits suggest generalist pollination system adapted for a guild of pollinating insects. The plant is self-incompatible and obligate out-crosser. The flowers are many-ovuled but only a single ovule forms seed and hence, fruit and seed set rates are the same. Natural fruit set stands at 11%. Bud infestation by a moth, flower predation by the beetle, Popillia impressipyga and bud and flower mounds significantly limit fruit set rate. The ability of the plant to repopulate itself is limited by the collection of fruits by locals due to their edible nature, short viability of seeds, high seedling mortality due to water stress, nutrient deficiency and erratic rainfall or interval of drought within the rainy season. Therefore, S. alternifolium is struggling to populate itself under various intrinsic and extrinsic factors. Further studies should focus on how to assist the plant to increase its population size in its natural area taking into account the information provided in this paper.

Population dynamics of Dasiops inedulis (Diptera: Lonchaeidae) and its biotic and abiotic mortality factors in Colombian sweet passionfruit orchards

Throughout South America, the lonchaeid flies Dasiops spp. are important herbivores of passionfruit crops. However, little is known on the biology and ecology of these insects, resulting in inadequate pest management schemes. In this study, we describe Dasiops inedulis population dynamics in Colombian sweet passionfruit (SP; Passiflora ligularis Juss.) and elucidate biotic mortality factors at different fly developmental stages. From August 2009 to July 2010, D. inedulis and Dasiops spp. abundance was assessed through monthly McPhail bait trapping and collection of SP flower buds, flowers, and immature fruits. Mortality levels of D. inedulis were determined for early instar larvae by ovary dissection and for late-instar larvae or pupae by prey removal trials. Maximum infestation reached 80 % in fruits and flower buds, and bud infestation correlated with precipitation during the previous month. Two days after oviposition, 8.2 ± 2.3 (mean ± SD) Dasiops sp. eggs were found in SP ovaries and 4.4 ± 1.2 late-instar larvae were recovered from immature fruits at day 14. Upon larval drop on the orchard soil, 74.8 % larvae burrowed within the soil within 9 min, while 12.5 % larvae were attacked by ants. In-field mortality of young pupae amounted to 75.3 ± 7.0 %, with vertebrate predators likely causing 12.1 ± 6.0 % mortality. Late-instar larvae and pupae appear highly vulnerable to natural enemy action, with the ground-foraging predator community mainly composed of ants (80.37 %) and ground beetles (9.17 %). Our findings should help develop integrated pest management (IPM) tactics for SP crops.

Prueba de extractos vegetales para el control de Dasiops spp., en granadilla (Passiflora ligularis Juss.) en el Huila, Colombia

Las moscas negras de la fruta (Dasiops spp.) son responsables de la caída de los botones florales y del daño en frutos en el cultivo de granadilla (Passiflora ligularis Juss.), causando pérdidas económicas a los cultivadores. El objetivo de este estudio fue determinar qué especies atacan botones florales y frutos de granadilla en el sur del Huila, evaluar y caracterizar el daño, conocer los enemigos naturales de Dasiops inedulis y evaluar el efecto insecticida de nueve extractos vegetales acuosos sobre adultos. Se muestrearon 30 fincas de granadilla en los municipios de Pitalito, Palestina, Isnos y Gigante (Huila, Colombia). Se encontraron las especies Dasiops inedulis infestando botones florales y D. yepezi, frutos. Los porcentajes de infestación de D. inedulis en botones florales oscilaron entre 3,87 ± 2,78 en Isnos y 24,60 ± 5,36 en Pitalito. Se encontró que el ataque fue más frecuente en botones de tamaño medio (2-4 cm). La relación de sexos fue de 1:1. Los enemigos naturales de D. inedulis encontrados fueron: Aspilota sp., Pentapria sp., Basalys sp., Pachycrepoideus vindemmiae y una especie de la subfamilia Eucoilinae. Los extractos vegetales que provocaron la mortalidad más cercana al testigo comercial en condiciones de casa de malla fueron los de Hura crepitans (Euphorbiaceae) al 5% (72,5% mortalidad) y Ricinus communis (Euphorbiaceae) al 25% (40% mortalidad); en las condiciones anteriores y en campo, el testigo comercial fue siempre más efectivo que los extractos vegetales. En condiciones de campo, el extracto que se diferenció del testigo absoluto fue el de R. communis al 25% con 40% de mortalidad.

Forecasting emergence and movement of overwintering hazelnut big bud mites from big buds

Eriophyoid big bud mites are key pests of hazelnut throughout the world, but they are difficult to control with chemicals or other methods because they are protected inside the bud. The most effective time for control is during the relatively short emergence period which is difficult for growers to predict. The key objectives of this study were to monitor mite emergence from big buds in spring, determine the phenology of mites in relation to tree phenology and weather, and identify the optimum timing for control measures. Mite emergence was found to occur between early and late spring in Canterbury, New Zealand. Mite emergence and movement occurred when daily maximum temperatures were >15 degrees C and when mean temperatures were >9 degrees C, with mite emergence increasing with temperature. The developmental status of new buds during mite emergence was a crucial factor in the infestation of new buds. An accumulated heat sum model (DD), starting at Julian date 152 and using a lower threshold temperature of 6 degrees C, predicted the onset of emergence on two cultivars and at two sites at approximately 172 DD. A regression model based on leaf number, bud length, bud width, DD and Julian date provided a more satisfactory prediction of percent accumulated mite emergence. It is recommended both peak mite emergence and the developmental status of hazelnut buds be used to optimise the time to apply control measures. The optimum time to apply a control was predicted to be before buds measure 0.5 x 0.5 mm (width x length), are enclosed within the axil, and have a rounded tip, or, when 50% accumulated mite emergence has occurred, whichever occurs first.

Repellence of the red bud borer Resseliella oculiperda from grafted apple trees by impregnation of rubber budding strips with essential oils

The red bud borer Resseliella oculiperda (Rübs.) is a pest insect of apple trees when rootstocks are grafted with scion buds by 'shield budding'. The female midges are attracted to the wounds of the grafted buds where they lay their eggs. The larvae feed on the cambium and destroy the buds completely or partially, leading to bad union of the buds with the rootstocks. Budding strips are used very often by growers to bind scion buds to rootstocks. These strips cannot prevent midges from reaching the damaged tissue. Chemical treatments applied to the grafts and other types of strip do not provide better protection against the pest and may cause other risks for growers. In orchard experiments in 2000 and 2001, the authors evaluated the repellent action provided by three essential oils and five compounds of plant origin against the midges by impregnating budding strips with them. The essential oils of lavender, Lavandula angustifolia (P. Mill.), and alpha-terpineol decreased the infestation of buds by more than 95 and 80% respectively. The other potential repellents tested [the essential oil of Juniperus virginiana (L.), citronellal, the essential oil of Cinnamomum camphora (L.) J. Presl, R-carvone, linalool and R-fenchone] decreased infestation by 67, 66, 51, 45, 37 and 25% respectively. The formulation and commercial development of budding strips impregnated with lavender oil is discussed.

SUSCEPTIBILITY OF SOME MANGO VARIETIES TO THE BUD MITE ERIOPHYES MANGIFERAE (SAYED) AND MAL-FORMATION DISEASE AND THE RELATION OF MITE INFESTATION TO MALFORMATION DISEASE

In field study, Eleven mango varieties, (Mangiferae indica L.) at Sharkia, Ismailia, and Fayoum Governorates, were examined to estimate the population fluctuation of the bud mite Eriophyes mangiferae Sayed, their susceptibility to mite infestation, the relation between the mite infestation and chemical contents of mango buds and the correlation between the bud mite and malformation disease. The highest population occurred during Sept. to Jan. or Feb. and the lowest population was existed during Mar. to Jun. Temperature and relative humidity had no significant effect on the mite population. The highest level of mite infestation was recorded at Sharkia followed by Fayoum and Ismailia Governorates. Mango varieties were differed in their susceptibility to E. mangiferae infestation. Zebda, Taimour, Ewais and Arnaba were the most susceptible varieties, while Mabrouka, Company, Excellent Succari and White Succari were the least susceptible ones. On the other hand Mesk, Geolck and Alphonse varieties showed moderate susceptibility to mite infestation. Buds of some high susceptible varieties possessed a lower values of total carbohydrates and total soluble sugars than some moderate or susceptible varieties to mite infestation. Phenol contents recorded a higher levels in the most of susceptible varieties while a lower levels were found in the most of moderate and low susceptible varieties. The total soluble proteins and amino acids recorded a higher values in some susceptible varieties. The susceptible characteristic was positively correlated with total soluble proteins and amino acids while negatively correlated with the total carbohydrates and total soluble sugars. However the phenol content showed no clear trend. Obtained results also revealed that mango varieties had varying degrees of floral malformation, Company, Alphonse and Geolck were the most susceptible varieties, while Zebda var. was the most resistant one. Statistical analysis showed a negative correlation between the eriophid bud mite and the incidence of malformation disease. Zebda var. harboured the highest number of mites but exhibited the lowest percentages of malformation, whereas the opposite trend was observed with company var

Relationship between capitulum size and pre-dispersal seed predation by insect larvae in common Asteraceae.

The evolution of a showy floral display as an advertisement to pollinators could simultaneously advertise the availability of resources to pre-dispersal seed-predators. The hypotheses tested here are that the incidence of seed predation by bud-infesting insect larvae in capitula of Asteraceae is positively related to (1) capitulum size among species, (2) capitulum size within species, (3) capitulum lifespan, and (4) the degree of flowering asynchrony on individual plants. Three populations of each of 20 common herbaceous species of Asteraceae from disturbed ground and grassland habitats were monitored for the presence of pre-dispersal, seed-eating insect larvae. Mean capitulum size (receptacle width) of each species was measured. In a sub-set of eight species, individual capitula were tagged to determine their flowering phenology and lifespan (from anthesis to seed shedding). From these data an index of flowering synchrony on individual plants was derived. Among species, the incidence of larval infestation increased with capitulum size. Small-flowered species such as Achillea millefolium were largely free of bud-infesting larvae, whilst large-flowered species such as Arctium minus were heavily infested. In three cases investigated in greater detail, bud infestation was found to increase with capitulum size within species, suggesting a potential for natural selection to favour smaller capitula. No relationship was found between infestation levels and either capitulum lifespan or degree of flowering synchrony, and there was no evidence that the relationship between capitulum size and infestation was confounded by correlations with these other features. The results support hypotheses 1 and 2, but not 3 and 4. It is suggested that the characteristic capitulum size of each species may represent a trade-off between the opposing selection pressures of pollinators and pre-dispersal seed predators.

Rearing Eriophyes insidiosus Keifer and Wilson (Acari: Eriophyoidea), a fastidious bud mite

Eriophyes insidiosus Keifer and Wilson is a fastidious bud mite which reproduces only inside buds of its host. These buds provide microenvironmental and physical conditions that are difficult to reproduce artificially. In this study, rearing of E. insidiosus was attempted on peach (Prunus persica Batsch, Rosaceae) cuttings generated by tissue culture, by rooting infested peach cuttings, and on peach trees that were infested naturally or manually. Manual infestation of buds, soon after dormancy ended, was the most successful technique, providing large numbers of mites. Availability of this methodology will contribute to the progress of studies on the relationships between bud-mite vectors and the viruses they transmit.

GALL MIDGES, CONTARINIA AGRIMONIAE FELT AND DASINEURA SPP. (DIPTERA: CECIDOMYIIDAE), ASSOCIATED WITH BLACKBERRY FLOWER INJURIES AND NUBBINS

Larvae of Contarinia agrimoniae Felt, a gall midge, were discovered during 1986 in blossoms of blackberry cultivars and wild-growing plants that had a history of poor fruit set and `nubbin' formation (Stiles, Semtner, and Reed, 1996). Other species damage blackberries in Europe, but the only North American recognition of Rubus flower bud infestation was with Dasineura rubiflorae Felt during 1886 (Gagne, 1989). During 1995 we found larvae of a Dasineura spp. in damaged buds at two, widely separated, commercial, North Carolina, blackberry sites. It is not known if the latter insects are different from the species that was collected during 1886. Midge larvae probably overwinter in soil under affected plants so we sprayed diazinon on the soil surface before bloom to kill larvae or interfere with pupation and reduce crop injuries. Infested `Shawnee' and `Cheyenne' buds were ≈100% more numerous among controls than diazinon-treated plots. Numbers of larvae varied among infested buds; 83 were observed in one bud from a nontreated `Cheyenne' plot.