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The causes and consequences of flower feeding for facultative florivores are poorly understood. Several factors can influence host selection and may, by extension, influence host part selection. Two such factors cited for the facultative florivore, Liriomyza trifolii (Burgess), are the optimisation of adult performance and natal habitat preference induction (NHPI) – a change in preference for a habitat in response to cues associated with the natal habitat. In this study we compared the nutritive and physical qualities of leaves and petals of Gerbera jamesonii, measured the survival and fitness of adults flies reared on leaves, flowers or a mixed diet, and investigated the influence of NHPI on adult host part choice. Liriomyza trifolii exhibited more than 50% higher lifetime fecundity on a mixed diet than on strict diets of leaves or flowers. Newly emerged adult flies exposed to leaves for 24 h showed a significant preference towards leaves, while flower-exposed flies showed no significant preference; flower-exposed flies were thus more than twice as likely as leaf-exposed flies to feed and oviposit on flowers. These results suggest that the optimisation of adult performance may be driving facultative florivory for L. trifolii in general, but the degree of florivory expressed is influenced by early adult experience, as NHPI explained 33% and 39% of feeding and oviposition host part choice, respectively. The potential for NHPI to influence the spatiotemporal occurrence of florivory is discussed.

*† Summary Glucosinolates are a class of secondary metabolites with important roles in plant defense and human nutrition. To uncover regulatory mechanisms of glucosinolate production, we screened Arabidopsis thaliana T-DNA activation-tagged lines and identified a high-glucosinolate mutant caused by overexpression of IQD1 (At3g09710). A series of gain- and loss-of-function IQD1 alleles in different accessions correlates with increased and decreased glucosinolate levels, respectively. IQD1 encodes a novel protein that contains putative nuclear localization signals and several motifs known to mediate calmodulin binding, which are arranged in a plant-specific segment of 67 amino acids, called the IQ67 domain. We demonstrate that an IQD1GFP fusion protein is targeted to the cell nucleus and that recombinant IQD1 binds to calmodulin in a Ca 2þ dependent fashion. Analysis of steady-state messenger RNA levels of glucosinolate pathway genes indicates that IQD1 affects expression of multiple genes with roles in glucosinolate metabolism. Histochemical analysis of tissue-specific IQD1::GUS expression reveals IQD1 promoter activity mainly in vascular tissues of all organs, consistent with the expression patterns of several glucosinolate-related genes. Interestingly, overexpression of IQD1 reduces insect herbivory, which we demonstrated in dual-choice assays with the generalist phloemfeeding green peach aphid (Myzus persicae), and in weight-gain assays with the cabbage looper (Trichoplusia ni), a generalist-chewing lepidopteran. As IQD1 is induced by mechanical stimuli, we propose IQD1 to be novel nuclear factor that integrates intracellular Ca 2þ signals to fine-tune glucosinolate accumulation in response to biotic challenge.

Summary Liriomyza trifolii is a serious pest of chrysanthemum greenhouses and other crops around the world. The larvae feed within the leaves of the host plants and create serpentine mines. The Sterile Insect Technique (SIT) has been successfully used against some Dipteran species in the field, and it is especially efficient against isolated populations like those on islands. Therefore, SIT against pest populations in confined environments such as greenhouses should have high potential for success. The objectives of this study were to determine the optimum gamma-irradiation dosage required for the sterilisation of L. trifolii adults, and to determine the quality (emergence percentage, flight ability, longevity, copulatory success, and sperm transfer) of the irradiated males compared with that of non-irradiated (normal) males. We found that sterility (< 0.7 mine per female) was achieved with the dose of 170 ± 5% Gy. The copulatory success and sperm transfer during copulation of the sterile males were not significantly different from those of normal males. Moreover, the longevity, emergence percentage and flight ability of irradiated males were also not significantly different from normal males. The SIT experiments suggest that the release of sterile L. trifolii can significantly reduce the reproductive capacity of a wild leafminer population. Our studies indicate that sterilisation of L. trifolii flies is feasible and that sterile males are of high quality and competitive with normal males. Based on these data, research on the use of SIT against L. trifolii populations in greenhouses is ongoing.

1 Maintenance of floral diversity throughout the growing season in vineyards in the form of summer cover crops of buckwheat (Fagopyrum esculentum Moench) and sunflower (Helianthus annus Linnaeus), had a substantial impact on the abundance of western grape leafhoppers, Erythroneura elegantula Osborn (Homoptera: Cicadellidae), and western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and associated natural enemies. 2 During two consecutive years, vineyard systems with flowering cover crops were characterized by lower densities of leafhoppers and thrips, and larger populations and more species of general predators, including spiders. 3 Although Anagrus epos Girault (Hymenoptera: Mymaridae), the most important leafhopper parasitoid, achieved high numbers and inflicted noticeable mortality of grape leafhopper eggs, no differences in egg parasitism rates were observed between cover cropped and monoculture systems. 4 Mowing of cover crops forced movement of Anagrus and predators to adjacent vines resulting in the lowering of leafhopper densities in such vines. 5 Results indicate that habitat diversification using summer cover crops that bloom most of the growing season, supports large numbers of predators and parasitoids thereby favouring enhanced biological control of leafhoppers and thrips in vineyards.

The authors examined situational and affective risk factors associated with the use of alcohol and other drugs. Five primary substance groups (alcohol, cocaine, marijuana, sedatives-tran-quilizers, and heroin-opiates) were compared on situational risk scales from the Inventory of Drinking and Drug Use Situations. Significant differences were found between groups on both level and pattern of situational and affective risk. Positive social experiences and negative affective states were important risk factors for the alcohol and cocaine groups. Positive affective and situational factors were important for the marijuana group. Negative physical states and interpersonal conflict were important risk factors for the heroin-opiate and sedative-tran-quilizer groups. Age and gender were also found to be significantly related to level and pattern of situational risk for alcohol and other drug use.

The effect of foliage feeding by the serpentine leafminer, Liriomyza trifolii (Burgess), on seed production and germination by male-sterile marigolds (Tagetes erecta L.) was examined over two cropping seasons in commercial production greenhouses. Five components of T. erecta relative fitness (the number of flowers, ovules, and germinations per plant, seed mass, and plant height) were compared in plants grown under four different control strategies representing three different intensities of L. trifolii herbivory: no control (high herbivory), biological or chemical control (intermediate herbivory), and insect-free (low herbivory). In both years of the study, significant between-treatment differences in number of viable seeds per plant were detected but no significant differences were found in the other four relative fitness measures. The number of viable seeds was highest with high herbivory (no-control treatments) and lowest with comparatively low herbivory (chem- ical and insect-free treatments). L. trifolii damage may reduce photosynthate availability, which may slow seed development and increase the length of time in which ovule physi- ological and morphological conditions are suitable for successful fertilization. Because all plants within each year received an equal number of pollinations occurring at the same time relative to plant growth, ovules within plants in the high-damage treatments may have had a greater probability of being fertilized, resulting in an increase in production of viable seeds.

1. Sex ratio in the ectoparasitoid, Diglyphus begini (Ashmead), attacking larvae of the dipterous leafminer Liriomyza trifolii (Burgess) in glasshouse marigolds, is best depicted by a model where sex ratio varies as a function of host size. 2. Male D. begini progeny are produced in hosts significantly smaller in size than those producing female progeny. 3. Female wasps attack and oviposit on the largest leafminer larvae available and whether a host is large or small depends upon the size of the other hosts attacked. 4. Diglyphus begini females adjust the thre:shold size for the change-over in sex allocation relative to the size of hosts attacked; however, the sex ratio is maintained at between 60% and 70% males. 5. The patterns observed in these glasshouse studies are not due to sex-specific differential mortality or superparasitism.

SUMMARY Investigation of the dispersal of Liriomyza trifolii in a 1–2 ha chrysanthemum greenhouse indicated that the average distance flown by female flies was greater than that flown by male flies. However, flies of both sexes were found at the furthest distance from the release point (102 m) which indicates that flies in the greenhouse could be considered to be a single inter-breeding population. When the data were fitted to a generalised distance-dispersal model, examination of the parameters revealed density decreased with distance more rapidly for males than females. Also, the model showed that males tended to be slightly more attracted to each other than were females. The applicability of these results to the development of pest management systems for L. trifolii is discussed.

The leaf puncturing, ovipositional and feeding behavior of Liriomyza trifolii was investigated on a preferred and non-preferred host (chrysanthemum and tomato, respectively). The sequence of leaf-puncturing behavior was stereotypic on both hosts, with a high probability of transition from one event to the next once the sequence is initiated. Two types of leaf punctures were made: a large fan-shaped puncture without an egg and tubular-shaped punctures with or without an egg. Regardless of the type of leaf puncture created, the female always backed over the puncture to feed. Therefore, all leaf punctures can be considered as feeding punctures. Fewer slow abdominal thrusts were noted for flies during oviposition compared to leaf puncturing only on chrysanthemum and tomato. The major differences noted between hosts were that L. trifolii fed for a significantly shorter period and spent less time during the leaf puncturing sequence on tomato vs. chrysanthemum. This suggests a repellent/antifeedant present in the former host which is detected through gustatory mechanisms. The deposition of an epideictic pheromone during oviposition was not detected. RESUME Comportements de piqure des feuilles, d'alimentation et de ponte de Liriomyza trifolii L'etude des comportements de piqure, de ponte et d'alimentation de Liriomyza trifolii a ete realisee sur hotes preferes ou non (Chrysantheme ou tomate). Les sequences du comportement de piqure de feuilles sont stereotypees sur les deux plantes, avec une forte probabilite de transmission d'une sequence a la suivante quand le comportement a debute. Il y avait deux types de piqures de feuilles: de larges piqures coniques sans oeufs et des piqures tubulares avec ou sans oeuf. Sans consideration du type de piqure, la femelle retourne sur la piqure pour s'alimenter. Ainsi, toutes les piqures peuvent etre considerees comme des piqures alimentaires. Moins de lentes contractions abdominales ont ete observees chez les mouches pondant que chez celles piquant uniquement, tant sur chrysantheme que tomate. Les principales differences observees entre hotes ont ete que L. trifolii s'alimentait pendant moins longtemps et passait moins de temps pendant la perforation sur tomate que sur chrysantheme. Ceci suggere la presence d'un repulsif/dissuadant chez la tomate qui serait decele par la gustation. Aucun depot de pheronome epideictique n'a ete mis en evidence pendant la ponte.

Diglyphus begini (Ashmead) (Hymenoptera: Eulophidae) is a larval ectoparasitoid of the leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). Female wasps oviposit on larvae which are significantly larger than larvae utilized for host feeding or hosts rejected for oviposition or feeding. Host size is evaluated on a relative rather than absolute basis. Individual female reproductive success increases with host size because of accompanying increases in offspring survivorship and adult body size. The number and duration of parasitoid stings is significantly greater when host feeding compared to oviposition and host rejection due to extensive probing of the internal viscera of larvae with the female ovipositor when host feeding. Upon host paralysis, 47.5% of parasitoid eggs become displaced from their host. However, eggs experimentally placed a mean distance of 0.8 mm away from a host do not result in a reduction in offspring survivorship compared to eggs attached to a host. Resume Comportement de Diglyphus begini lors de l'attaque de Liriomyza trifolii sur chrysanthemes La mineuse L. trifolii Burgess attaque de nombreuses cultures a travers le monde. L'eulophide, D. begini Ashmead, est un parasitoide frequent du diptere. L'objectif de nombreux praticiens de la lutte biologique est de pouvoir predire le resultat de lâchers d'ennemis naturels. Cette etude a ete entreprise en estimant que la connaissance du comportement de prospection aide a comprendre la dynamique des interactions des populations hotes et parasites. Une attaque de D. begini se concretisant par une ponte, est generalement caracterisee par deux piqures de duree limitee avec emission de l'œuf normalement au cours de la seconde piqure. L'alimentation aux depens de l'hote est caracterisee par des piqures prolongees et repetees. Les hotes refuses pour la ponte ou l'alimentation sont piques une fois ou deux, les deux piqures etant tres breves. L'aptitude de D. begini a percevoir les differences de tailles des larves de L. trifolii augmente la valeur adaptative individuelle des parasites. Les femelles ne pondent que dans les hotes les plus grands, ce qui augmente le taux de survie des descendants et la taille des adultes. Puisque la taille des hotes est evaluee sur une base relative, la valeur adaptative du parasite est independante des changements de distribution des tailles des hotes rencontres. Les larves de L. trifolii utilisees comme hotes ne deviennent pas immediatement immobiles apres avoir ete attaquees. Ceci fait que de nombreux œufs peuvent etre deloges de leur hote. Nous avons ete incapables de deceler quelque effet nocif de ces mouvements de l'hote apres la ponte sur la survie des œufs de D. begini.