Efficacy of inoculative releases of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) against European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) in field corn

We evaluated the egg parasitoid Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) to control European corn borer [Lepidoptera: Crambidae: Ostrinia nubilalis (Hübner)] in field corn in 2001 and 2002. Inoculative releases of 75,000 T. ostriniae/ha occurred in New York and Virginia in 5–10 cornfields per state when corn was at mid-whorl. Incidence of egg mass parasitism, number of stalk tunnels, incidence of ear damage, and whole-plant yield were evaluated. Parasitism of European corn borer egg masses ranged from 0 to 75% in release plots and was greater in release plots than in control plots. Individual comparisons between paired release and control plots showed no reductions in either stalk or ear damage. However, when data were combined across both years and fields, stalk and ear damage were significantly reduced in New York. In Virginia, no significant differences were detected using data obtained from one year. There were no differences in yield between release and control plots. Low densities of European corn borer, drought conditions in 1 year, and a larger plant canopy in field corn are possible reasons why T. ostriniae releases provided less control than has been observed in previous trials in sweet corn. Additional research focused on improved timing and frequency and number of releases is warranted.     

Geographic range, impact, and parasitism of lepidopteran species associated with the invasive weed Lantana camara in South Africa

Six isolates of Trichoderma were screened for antagonism to Armillaria in tea stem sections buried in the soil. The inability of Armillaria to invade Trichoderma-colonized stem sections and the reduction of its viability in the plant materials following invasion of these by Trichoderma were used as indicators of antagonism. Four isolates of the species Trichoderma harzianum significantly (P<0.001) reduced the incidence of the pathogen in the plant materials. Isolate T4 completely eliminated the pathogen from plant materials in sterile soil and also antagonized two different isolates of the pathogen in nonsterile soil. Application of this T. harzianum isolate to the soil as a wheat bran culture significantly (P<0.001) reduced viability of Armillaria in woody blocks of inoculum. Soil amendment with coffee pulp also reduced the inoculum viability but did not affect the incidence of Trichoderma in the blocks of inoculum. We conclude that the direct application of wheat bran-formulated T. harzianum into soil surrounding woody Armillaria inoculum sources can suppress the pathogen. Further, no organic amendment is needed to enhance development of the antagonist in the soil as a pre-requisite to suppressing the pathogen.     

Establishment ofNeltumius arizonensis(Coleoptera: Bruchidae) on Mesquite (ProsopisSpecies: Mimosaceae) in South Africa

Species ofProsopis(Mimosaceae), or mesquites, are invasive rangeland weeds in South Africa's Western Cape and Northern Cape Provinces. Two bruchid seed-weevil species,Algarobius prosopis(Le Conte) andA. bottimeriKingsolver, were released for biological control in 1987 and 1990, respectively. Seed-feeding biocontrol agents were selected because mesquite pods are valued as livestock fodder. Livestock grazing of bruchid larvae developing in mesquite seeds, however, limits the effectiveness of these agents. Livestock grazing also exacerbates mesquite infestations because scarified seeds are dispersed widely in vertebrate dung. In response to the livestock grazing problem,Neltumius arizonensis(Schaeffer), a bruchid reputed to be capable of ovipositing on immature, tree-borne pods, was released at three sites in Western Cape Province in 1993 and 1994. Small populations ofN. arizonensishave become established at the release sites. Overall,N. arizonensiswas 18 times less abundant thanA. prosopis.In some monthsN. arizonensiseggs were heavily parasitized byUscanasp. (Trichogrammatidae), but the effect of this onN. arizonensispopulation dynamics is uncertain. Western CapeN. arizonensispopulations need more time to increase in size. The introduction of other, more injurious biocontrol agents such as the cecidomyiid bud feederAsphondylia prosopidisCockerell should be considered.     

Vine mealybug sex pheromone increases citrus mealybug parasitism by Anagyrus sp. near pseudococci (Girault)

The present study was aimed at elucidating the role of lavandulyl senecioate (LS), the sex pheromone of Planococcus ficus, in host selection of the parasitoid Anagyrus sp. near pseudococci. Field trials were carried out in Portugal, Italy and Israel. The effect of LS on the parasitism rate of the wasp was determined by exposing sentinel mealybugs combined with pheromone dispensers impregnated with LS, in comparison with other baits: lavandulyl isovalerate (LI); planococcyl acetate (PAc); and unbaited control traps. In addition, in order to study the host location behavior of A. sp. near pseudococci, pheromone dispensers were placed at three different distances: inside the trap, 30 or 60 cm away from the trap. The number of parasitoid females inside the traps, the number of parasitized mealybugs, and the number of days required for the first parasitoid emergence were recorded. The response of A. sp. near pseudococci females to different doses of LS (25–1350 μg) was also evaluated using sticky plate traps. The rate of mealybug parasitism by A. sp. near pseudococci was significantly increased by LS in the three parasitoid populations. PAc and LI had no significant effect on the wasp parasitism rate in most of the trials. However, the Italian population of the parasitoid responded to PAc, showing apparently a different behavioral pattern. The number of parasitoid females trapped did not significantly differ between tested doses of LS. The use of LS as an arrestant in host location by the A. sp. near pseudococci female is discussed.     

Parasitism by Pteromalus cerealellae (Hymenoptera: Pteromalidae) on the Cowpea weevil, Callosbruchus maculatus (Coleoptera: Bruchidae): Host density, temperature effects, and host finding ability

Studies on interactions between a larval parasitoid, Pteromalus cerealellae (Boucek) and one of its hosts, Callosobruchus maculatus (F.) were carried out in the laboratory. The number of host larvae parasitized by P. cerealellae increased with host larvae at low densities and tended to a plateau at a density of 25 larvae per female parasitoid. Each parasitoid was able to parasitize more hosts and produced more offspring at 20 and 25 °C than at 30 °C. The number of non-infested seeds mixed with seeds infested with the last instar of C. maculatus did not preclude P. cerealellae from identifying infested seeds and attacking larvae inside them. When infested seeds were tightly packed, several host larvae escaped parasitism. P. cerealellae may be a useful biological control agent in newly harvested cowpea with low C. maculatus infestation, and lowering the temperature of the storage system may enhance the effectiveness of this parasitoid.     

Predation by Podisus maculiventris (Hemiptera: Pentatomidae) on Plutella xylostella (Lepidoptera: Plutellidae) larvae parasitized by Cotesia plutellae (Hymenoptera: Braconidae) and its impact on cabbage

Biological control offers potentially effective suppression of the diamondback moth (DBM), Plutella xylostella, a serious pest of Brassica crops. Little is known of whether multiple natural enemies have additive, antagonistic, or synergistic effects on DBM populations. No-choice and choice tests were conducted to assess predation by Podisus maculiventris on DBM larvae parasitized by Cotesia plutellae and unparasitized larvae. In no-choice tests, P. maculiventris preyed on greater numbers of parasitized than unparasitized larvae and greater numbers of young larvae than old larvae. In choice tests with early third instar DBM, there was no difference in predation between parasitized or unparasitized larvae. However, in choice tests with older prey, P. maculiventris preyed on more parasitized than unparasitized larvae. Two field studies were conducted to test if this predator and parasitoid have additive, antagonistic or synergistic effects on DBM populations and plant damage in cabbage (Brassica oleracea var. capitata). In 2002, DBM populations were significantly lower in the presence of C. plutellae but not in the presence of P. maculiventris. There was not a significant interaction between the natural enemies. Plant damage was reduced only with C. plutellae. In 2003, DBM populations were significantly lower in the presence of C. plutellae and P. maculiventris, although the combination of natural enemies did not lead to a non-additive interaction. Plant damage was unaffected by the presence of either natural enemy. Because of its greater predation on parasitized larvae, P. maculiventris could be an intraguild predator of C. plutellae. Yet, their overall combined effect in the field was additive rather than antagonistic.     

Life history of the tick parasitoid Ixodiphagus hookeri (Hymenoptera: Encyrtidae) in Kenya

We conducted laboratory and field experiments to elucidate the life history of Ixodiphagus hookeri, a parasitoid of the ixodid tick Amblyomma variegatum in Western Kenya. Ixodiphagus hookeri females oviposited in unfed host nymphs as well as engorged nymphs, but rarely in engorged larvae. While I. hookeri developed to adults in engorged nymphs, the eggs laid in unfed nymphs disappeared within 2 days after oviposition. As temperature increased, development time of I. hookeri from oviposition to adult emergence in engorged nymphs decreased from 46 days at 23 °C to 35 days at 28 °C, and their immature survival in engorged nymphs decreased from 67% at 23 °C to 22% at 28 °C. No parasitoid adult emerged from hosts at 30 °C. Individual hosts parasitized by single females produced 42–53 adult wasps, 73% of which were females. As a typical pro-ovigenic species, I. hookeri females had an average of 84 mature eggs at emergence and lived only for a few days. When laboratory-reared, unfed nymphs of A. variegatum were attached to cattle for 4–9 days in subsistence farmers’ fields in Western Kenya, 25% of the engorged nymphs and 4% of the unfed nymphs on cattle were parasitized by I. hookeri, demonstrating that I. hookeri females search for and oviposit in A. variegatum nymphs on cattle. Unlike other strains of I. hookeri that overwinter as eggs in unfed nymphs, I. hookeri could continuously reproduce throughout the year in Western Kenya.     

Disruption of parasitism of the California red scale (Homoptera: Diaspididae) by three ant species (Hymenoptera: Formicidae)

The relative influence of the southern fire ant, Solenopsis xyloni McCook, Argentine ant, Linepithema humile (Mayr), and native gray ant, Formica aerata (Francoeur), on parasitism of California red scale, Aonidiella aurantii Maskell, was studied in the laboratory for two parasitoids, Comperiella bifasciata Howard and Aphytis melinus DeBach. All three ant species reduced percentage parasitism by C. bifasciata and both percentage parasitism and host mutilation by A. melinus. Southern fire ant was the least disruptive and native gray ant the most disruptive. Southern fire ant removed 12% of scale from the lemons, presumably to feed on them, while the other ant species did not exhibit significant removal of scale compared to the controls. Percentage parasitism of California red scale exhibited by C. bifasciata was more than 2-fold the level exhibited by A. melinus. Percentage mutilation of California red scale, including probing and host feeding, was nearly 5-fold higher for A. melinus than C. bifasciata. Because A. melinus required a longer total host examination + oviposition period in the absence of ants than C. bifasciata and because oviposition occurs as the last act in a sequence of behaviors, disruption by the ants had a more significant negative effect on oviposition by A. melinus.     

Production of Anagrus epos Girault (Hymenoptera: Mymaridae) on Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) eggs

Anagrus epos Girault (Hymenoptera: Mymaridae) is a natural enemy candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Little is known about the biology or ecology of A. epos when it utilizes GWSS eggs as a host. Here, we report the results of laboratory studies that describe the host age preference for oviposition, longevity of A. epos adults provided with different food sources, and developmental rates at six different constant temperature regimes. Anagrus epos is a gregarious parasitoid in GWSS eggs with up to 14 adults emerging from each GWSS egg. In choice and no-choice tests for oviposition, A. epos females successfully parasitized all developmental ages of GWSS eggs (1–8 days old). In choice tests, parasitism rates were significantly higher in 1-, 3-, 4-, and 5-day-old GWSS eggs than in 2-, 6-, 7-, and 8-day-old eggs. If provided with honey and water, honey only, water only, or no food or water, A. epos females lived on average 8.2, 4.7, 2.6, and 1.6 days, respectively. Anagrus epos required 294.1 degree-days above a lower temperature threshold of 12.4 °C to develop from egg to adult (eclosion). Our results provide baseline information useful in the development of an efficient parasitoid mass rearing program for A. epos release and evaluation in California.     

Alcidodes sedi (Col.: Curculionidae), a natural enemy of Bryophyllum delagoense (Crassulaceae) in South Africa and a possible candidate agent for the biological control of this weed in Australia

The Madagascan endemic, Bryophyllum delagoense (Crassulaceae), is a major weed in Queensland, Australia. Despite having first been recorded in Australia in the 1940s, it is far more invasive there than on the African mainland where it was introduced more than 170 years ago. This may be due to a number of factors, one of which could be the occurrence of new natural enemy associations in southern Africa. Among the insects of crassulaceous plants that have extended their host ranges, a stem-boring weevil, Alcidodes sedi, was studied to elucidate its status as a natural enemy of B. delagoense in southern Africa and as a candidate biological control agent for introduction to Australia. Laboratory studies indicated that damage inflicted by adult and larval feeding caused significant reductions in stem length and number of leaves. Preliminary host-range trials revealed that A. sedi can complete its development on other species in the Crassulaceae, including most of the introduced Bryophyllum species and some Kalanchoe species native to South Africa. Despite the oligophagous nature of A. sedi and the fact that it can complete its development on a number of ornamental species in the Crassulaceae, it should be considered a potential biological control agent in Australia. All of the native Crassulaceae in Australia are in the genus Crassula, most of which are very small and therefore unlikely to support the development of a large weevil like A. sedi. However, additional host-range trials will have to be undertaken in Australia to determine whether the weevil can be considered safe for release.     

The biology of Phymastichus coffea LaSalle (Hymenoptera: Eulophidae) under field conditions

The coffee berry borer (CBB) Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) was accidentally introduced into México in 1978, and rapidly became the main pest of coffee. As an exotic pest, its management has been mainly based on biological control methods through the introduction of parasitoids from Africa. In this context, at the beginning of the present decade, the parasitoid Phymastichus coffea LaSalle (Hymenoptera: Eulophidae) was imported to Mexico. Since then, several studies have been carried out as part of the post introduction evaluation of this parasitoid. In this paper, information concerning the parasitism and life-cycle of P. coffea in coffee farms is presented with the objective of providing information that elucidates its role as a biological control agent. P. coffea showed highly significant preferences for allocation of two eggs per host, usually one female and one male. Both offspring are able to develop and reach the adult stage successfully. Lifespan of adults is 2–3 days only. The degree of parasitism by P. coffea was more than 95% at the three altitudes tested, when releases consisted of a ratio of 10 CBB:1 parasitoid. The median survivorship of CBB parasitized by this wasp was 13, 15 and 19 days at the low, medium and high altitude coffee zones, respectively. The parasitism by P. coffea was higher when parasitoid releases were carried out simultaneously with the CBB, and decreased with the time between host and parasitoid releases. We showed that using P. coffea at a density of 1 parasitoid per 10 hosts resulted in a 3- to 5.6-fold decrease in CBB damage to the coffee seeds when compared to the control. The importance and value of these results are discussed in terms of the use of P. coffea as a biological control agent of the CBB in Latin America.     

Lysis of Aphanizomenon flos-aquae (Cyanobacterium) by a bacterium Bacillus cereus

A phytoplankton-lytic (PL) bacterium, Bacillus cereus, capable of lysing the bloom-forming cyanobacterium Aphanizomenon flos-aquae was isolated from Lake Dianchi of Yunnan province, China. This bacterium showed lytic activities against a wide range of cyanobacteria/algae, including A. flos-aquae, Microcystis viridis, Microcystis wesenbergi, Microcystis aeruginosa, Chlorella ellipsoidea, Oscillatoria tenuis, Nostoc punctiforme, Anabaena flos-aquae, Spirulina maxima, and Selenastrum capricornutum. Chlorophyll a contents, phycocyanin contents, and photosynthetic activities of the A. flos-aquae decreased evidently in an infected culture for a period. Bacterium B. cereus attacked rapidly A. flos-aquae cells by cell-to-cell contact mechanism. It was shown that the lysis of A. flos-aquae began with the breach of the cyanobacterial cell wall, and the cyanobacterial cell appeared abnormal in the presence of the PL bacterium. Moreover, transmission electron microscope examinations revealed that a close contact between the bacterium and the cyanobacterium was necessary for lysis. Some slime extrusions produced from B. cereus assisted the bacterial cells to be in close association with and lyse the cyanobacterial cells. These findings suggested that this bacterium could play an important role in controlling the Aphanizomenon blooms in freshwaters.     

Discovery of a CI-inducing Wolbachia and its associated fitness costs in the biological control agent Aphytis melinus DeBach (Hymenoptera: Aphelinidae)

Wolbachia is an endosymbiotic bacterium that infects a large percentage of arthropods and can affect the fitness of its host. Here we verified for the first time that the biological control agent Aphytis melinus DeBach is infected with a Wolbachia that causes complete cytoplasmic incompatibility, and conducted an insectary and field survey to determine the infection frequency. A. melinus appears to suffer fitness costs associated with infection based on measurements of longevity and fecundity. We also quantified the Wolbachia titers of A. melinus reared at different temperatures and found that, although not completely cured, increased temperature resulted in a significant reduction in the number of Wolbachia copies found in an individual wasp. Implications of our results for biological control are discussed.     

Evaluation of the local population of Eretmocerus mundus (Hymenoptera: Aphelinidae) for biological control of Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) in greenhouse peppers in Argentina

Bemisia tabaci biotype B is a key pest in pepper crops in Argentina. The parasitoid Eretmocerus mundus is frequently found parasitizing this whitefly in greenhouses without pesticide applications. The present studies were carried out with the objective of evaluating control obtained with different rate and number of parasitoid releases under experimental conditions. Release rate: cages with pepper pots were positioned in an experimental greenhouse and randomly assigned to the release rate treatments (0, 1 and 3 pairs of E. mundus/plant/week with a total of three introductions). Number of releases: similar cages were assigned to the number of parasitoid introduction treatments (0, 1, 2 and 3) with the best release rate obtained in the previous trial. In both assays whitefly (adults and nymphs) and parasitoid (parasitized nymphs) population sizes in each cage were monitored weekly for a period of 10 weeks. Results suggested that the introduction of 2 E. mundus/plant/week was enough to suppress host population compared to control treatment (peaks of 7.75 adults and 58.75 nymphs/cage and 643.75 adults and 1598 nymphs/cage, respectively) (p < 0.05), with 85% of parasitism. E. mundus had to be introduced three times to achieve the best pest control (peaks of 1.17 adults and 20.33 nymphs/cage vs. 55.67 adults and 75 nymphs/cage in control treatment) with 84% of parasitism (p < 0.05). These results were then validated in a pepper crop under experimental greenhouse conditions. Whitefly population was lower in those greenhouses where E. mundus was released compared to control greenhouses (0.15 adults and 0.71 nymphs/4 leaves and 0.73 adults and 1.64 nymphs/4 leaves, respectively), with a peak of 54% of parasitism (p < 0.05). We concluded that good suppression of B. tabaci could be achieved using E. mundus under spring conditions in Argentina.     

Establishment of papaya banker plant system for parasitoid, Encarsia sophia (Hymenoptera: Aphilidae) against Bemisia tabaci (Hemiptera: Aleyrodidae) in greenhouse tomato production

The silverleaf whitefly, Bemisia tabaci biotype B (Gennadius) (Hemiptera: Aleyrodidae), is a key pest of tomato (Solanum lycopersicum L.) and other vegetable crops worldwide. To combat this pest, a non-crop banker plant system was evaluated that employs a parasitoid, Encarsia sophia (Girault & Dodd) (Hymenoptera: Aphelinidae) with whitefly, Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae), as an alternative host for rearing and dispersal of the parasitoid to the target pest. (a) Multi-choice and no-choice greenhouse experiments were conducted to determine host specificity of T. variabilis to papaya (Carica papaya L.) and three vegetable crops including tomato, green bean (Phaseolus vulgaris L.), and cabbage (Brassica oleracea L.). The result showed that papaya was an excellent non-crop banker plant for supporting the non-pest alternative host, T. variabilis, whose adults had a strong specificity to papaya plants for feeding and oviposition in both multi-choice and no-choice tests. (b) The dispersal ability of E. sophia was investigated from papaya banker plants to tomato and green bean plants infested with B. tabaci, as well as to papaya control plants infested with T. variabilis; and (c) the percent parasitism by E. sophia on T. variabilis reared on papaya plants and on B. tabaci infested on tomato plants was also evaluated. These data proved that E. sophia was able to disperse at least 14.5 m away from papaya plants to target tomato, bean or papaya control plants within 48–96 h. Furthermore, E. sophia was a strong parasitoid of both T. variabilis and B. tabaci. There was no significant difference in percent parasitism by E. sophia on T. variabilis (36.2–47.4%) infested on papaya plants or B. tabaci (29–45.9%) on tomato plants. Thus, a novel banker plant system for the potential management of B. tabaci was established using papaya as a non-crop banker plant to support a non-pest alternative host, T. variabilis for maintaining the parasitoid to control B. tabaci. The established banker plant system should provide growers with a new option for long-term control of B. tabaci in greenhouse vegetable production. Ongoing studies on the papaya banker plant system are being performed in commercial greenhouses.     

The control of Galba truncatula (Gastropoda: Lymnaeidae) by the terrestrial snail Zonitoides nitidus on acid soils

Field investigations on the control of Galba truncatula by Zonitoides nitidus were carried out over the past 30 years in the different types of lymnaeid habitats located in central France. When a layer of mowed vegetation was used to cover G. truncatula habitats at the end of June, the introduction of adult Z. nitidus (20/m²) eliminated lymnaeid populations after 2 years of control in habitats located in swampy meadows, around the heads of intermittent springs, in areas trampled by cattle, and along river or pond banks. In the case of wild watercress beds, 3 years were necessary. The best results (elimination of G. truncatula after a single year of control) were obtained using an association of snails (Z. nitidus + Oxychilus draparnaudi), or a mixed control (a first application of 0.1 mg/l CuCl₂, followed 3 months later by the introduction of Z. nitidus). Recolonization of treated habitats by G. truncatula coming from downstream populations was noted 3 years following the last application of biological control. Apart from the regular introduction of Z. nitidus in several watercress beds, the use of this snail to control G. truncatula has not become generalized in cattle- and sheep-breeding farms. The reasons for this situation are probably the complexity of applying this control in the field by nonspecialists and the difficulty of selecting the period of snail control at the end of June due to frequent local rainfall at this time.     

Successful oviposition and reproductive biology of Aprostocetus vaquitarum (Hymenoptera: Eulophidae): A predator of Diaprepes abbreviatus (Coleoptera: Curculionidae)

Aprostocetus vaquitarum (Wolcott) causes 78–91 percent mortality to eggs of Diaprepes abbreviatus (L.), under field conditions in southern Florida. In the laboratory, A. vaquitarum was reared on D. abbreviatus eggs at 25 °C, a photoperiod of 12:12 (L:D) and with abundant hosts, A. vaquitarum adult females lived around 15 days. Oviposition was significantly affected by the age of the host egg mass. Egg masses aged 0- to 3-day-old were accepted significantly better than those aged 4–6 days. The mean number of eggs deposited per female was around 53, with extreme values of 124 and 19 eggs per female. Using these data in combination with the sex ratio observed in the field (0.16) and the duration of the preimaginal stages, r_m (0.168–0142 day⁻¹), T (22.39–22.89 days), and R₀ (43.03–25.81 females per female) were calculated.     

Incidence of the introduced parasitoids Cotesia kazak and Microplitis croceipes (Hymenoptera: Braconidae) from Helicoverpa armigera (Lepidoptera: Noctuidae) in tomatoes, sweet corn, and lucerne in New Zealand

Morphological defense traits of plants such as trichomes potentially compromise biological control in agroecosystems because they may hinder predation by natural enemies. To investigate whether plant trichomes hinder red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), as biological control agents in soybean, field and greenhouse experiments were conducted in which we manipulated fire ant density in plots of three soybean isolines varying in trichome density. Resulting treatment effects on the abundance of herbivores, other natural enemies, plant herbivory, and yield were assessed. Trichomes did not inhibit fire ants from foraging on plants in the field or in the greenhouse, and fire ant predation of herbivores in the field was actually greater on pubescent plants relative to glabrous plants. Consequently, fire ants more strongly reduced plant damage by herbivores on pubescent plants. This effect, however, did not translate into greater yield from pubescent plants at high fire ant densities. Intraguild predation by fire ants, in contrast, was weak, inconsistent, and did not vary with trichome density. Rather than hindering fire ant predation, therefore, soybean trichomes instead increased fire ant predation of herbivores resulting in enhanced tritrophic effects of fire ants on pubescent plants. This effect was likely the result of a functional response by fire ants to the greater abundance of caterpillar prey on pubescent plants. Given the ubiquity of lepidopteran herbivores and the functional response to prey shown by many generalist arthropod predators, a positive indirect effect of trichomes on predation by natural enemies might be more far more common than is currently appreciated.     

Host suitability and preference studies of Trichogramma cordubensis (Hymenoptera: Trichogrammatidae)

Studies of host suitability and preferences of Trichogramma cordubensis Vargas and Cabello (Hymenoptera: Trichogrammatidae) were performed with eggs of six Lepidoptera (Noctuidae) species: Thysanoplusia orichalcea Fabricius, Peridroma saucia (Hübner), Xestia c-nigrum L., Phlogophora meticulosa (L.), Noctua pronuba (L.), and N. atlantica (Warren). Host suitability was studied by analysing separately the effects of the attacked host species and the influence of the rearing host species on different biological parameters of T. cordubensis. Host preference was analysed by offering eggs of two host species simultaneously to a single female wasp without previous oviposition experience (dual-choice tests). Results show that P. saucia, followed by P. meticulosa were the least suitable hosts for T. cordubensis, since on these species the preimaginal development of the parasitoids was significantly longer and, the number of parasitized eggs as well the number of offspring per female were significantly lower. Contrarily, T. cordubensis parasitized at a higher rate the eggs of the endemic non-target species, N. atlantica. Dual choice tests showed that the option of the first host to be accepted by the wasp was random; however, the mean number of parasitized eggs differed significantly when two host species were offered simultaneously to T. cordubensis, always being the host species with heavier eggs the most parasitized.     

Reproductive biology of Fopius ceratitivorus (Hymenoptera: Braconidae), an egg–larval parasitoid of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

The reproductive biology of Fopius ceratitivorus Wharton, a recently discovered African parasitoid, was studied in quarantine in Hawaii to facilitate its mass production for biological control of the Mediterranean fruit fly, Ceratitis capitata. Mean longevity of host-deprived and ovipositing females was 17.3 ± 0.9 d and 16.2 ± 0.5 d, respectively. Ovarian maturation peaked at 61.6 mature eggs per female on the fifth day after eclosion and declined thereafter. Mean number of offspring produced per day by mated females was 5.1 ± 0.4, and realized fecundity expressed as total eggs deposited during the female’s life time was 107.8 ± 12.8. Females were more attracted, to and reproduced significantly more, in fruit substrates containing odors of adult flies and eggs rather than fruit substrates artificially inoculated with fly eggs. Our findings suggest that F. ceratitivorus is a promising new parasitoid for biological control of C. capitata in Hawaii.