Identification of Prosopis juliflora and Prosopis pallida Accessions Using Molecular Markers

There has been much taxonomic confusion over the identification of Prosopis species, especially where introduced. Prosopis juliflora is the most widespread species in the arid and semi-arid tropics, although it has been confused with other species, particularly the closely related Prosopis pallida. In this study, RAPDs markers were used for the first time to distinguish between these species. Eighteen primers were used in amplification reactions, which yielded an average of 120 bands per accession. A dendrogram showing genetic similarities among accessions was constructed using UPGMA cluster analysis and the Nei and Li similarity coefficient. The genetic similarity observed between P. juliflora and P. pallida is similar to the value in sympatric Prosopis species in North America, and reconsideration of the series rank in section Algarobia is suggested. Species-specific markers confirmed that material in Burkina Faso is P. juliflora, but suggested that material collected in Brazil, Cape Verde and Senegal is P. pallida, whereas this has previously been identified as P. juliflora.     

Symbiotic properties of sinorhizobia isolated from Acacia and Prosopis nodules in Sudan and Senegal

The host specificity, infection process and effectiveness of nodules produced by several African sinorhizobial strains on different Acacia and Prosopis species (Leguminosae, Mimosoideae) were studied. Sinorhizobium arboris strain HAMBI 1552^T, S. kostiense strains HAMBI 1489^T and HAMBI 1493, S. saheli strain HAMBI 1496 and S. terangae bv. acaciae strain ORS 1058 induced nitrogen fixing nodules on seedlings of the following African or Latin American species (marked with ^*): A. angustissima ^* , A. mellifera, A. nilotica, A. oerfota (synonym A. nubica), A. senegal, A. seyal, A. sieberiana, A. tortilis subsp. raddiana, P. chilensis ^* , P. cineraria, P. juliflora and P. pallida ^* . All strains increased plant yield significantly compared with uninoculated seedlings watered with nitrogen-free medium, but none appeared to be superior. The sinorhizobial strains were unable to effectively nodulate Sesbania rostrata (Papilionoideae).All roots had hairs, but particularly in the case of Acacia spp. they were often sparse. After inoculation root hairs were deformed and, in general, infection in Acacia spp. occurred through short root hairs and in Prosopis spp. through longer ones. After entry, the rhizobia filled infection pockets in the root hair, which later expanded into sac-like structures. When infection threads occurred, they usually started from sac-like structures. Elongation and ramification of the nodules indicated that Acacia spp. and Prosopis spp. have indeterminate nodules. A persistent apical meristem, which is the characteristic feature of the indeterminate nodule type, was much clearer in Prosopis spp. than in Acacia spp. Sinorhizobial strains formed tumour-like structures with undifferentiated cell tissue on the Australian acacia A. holosericea and ineffective, nodule-like structures on the African P. africana.     

Host-recognition kairomone from Sogatella furcifera for the parasitoid Anagrus nilaparvatae

A kairomone produced by the rice white-backed planthopper Sogatella furcifera (Horvath) for the mymarid egg parasitoid Anagrus nilaparvatae Pang et Wang was investigated. Eggs, female and male adults, nymphs, exuvia, honeydew, nymph-damaged plants and plants with S. furcifera eggs all elicited searching behavior in the parasitoid. Eggs, female adults and plants with eggs were the most attractive, while exuvia and honeydew evoked the weakest responses. The active compound(s) from S. furcifera female adults, nymphs and plants with eggs could be effectively extracted with methanol, acetone, n-hexane, ethyl ether and dichloromethane. Isolation of the active chemical(s) in three solvent extracts, the acetone and n-hexane extracts of S. furcifera female adults, and the acetone extract of S. furcifera nymphs, was accomplished by thin-layer chromatography. Only one fraction was active and had the same chemical properties in the three solvent extracts. Infra-red analysis of this fraction revealed a kind of ester with saturated and unsaturated fatty acids, which was previously found to be active in the same compound as the extracts from the nymphs and female adults of the rice brown planthopper, Nilaparvata lugens (Stål), and identified as palm oil. The results are discussed in relation to host location by A. nilaparvatae.     

Comparative studies of predation among feral,commercially-purchased,and laboratory-reared predators

The predatory activities of commercially-purchased adult Hippodamia convergens Guérin-Méneville and two laboratory-reared strains of adult Geocoris punctipes (Say) were compared with their feral counterparts. In single prey choice feeding tests, commercially-purchased and feral H. convergens were provided copious amounts of silverleaf whitefly, Bemisia argentifolii Bellows & Perring adults or eggs of pink bollworm, Pectinophora gossypiella (Saunders). Commercially-purchased H. convergens devoured more pink bollworm eggs and at a faster rate than the feral H. convergens. In contrast, feral H. convergens consumed more adult whiteflies and at a faster rate than commercial H. convergens. In multiple feeding choice tests, two distinctly different laboratory-reared strains and feral G. punctipes were provided a cotton leaf disk containing copious amounts of silverleaf whitefly eggs, nymphs, and adults. Virtually no predation was observed on whitefly eggs, but both laboratory strains of G. punctipes fed on more whitefly nymphs and adults than the feral G. punctipes. Moreover, both of the laboratory strains had a significantly faster feeding rate on adult whiteflies and spent significantly less time feeding on plant tissue than the feral strain. These results suggest that the augmentative biological control candidates retained their ability to prey on these selected prey items, even after being displaced from their overwintering site (H. convergens) or being reared in captivity (G. punctipes) for over 40 generations. Handling editor: Patrick De Clercq. This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the USDA.     

Effect of Starvation on the Searching Path of the Predatory Bug <Emphasis Type="Italic">Deraeocoris Lutescens</Emphasis>

As physiological factors may influence the predatory behavior of insects, this study was designed to evaluate the possible impact that hunger has on the search path of a polyphagous predator: Deraeocoris lutescens Schilling (Heteroptera: Miridae). D. lutescens was fed a diet of Rhopalosiphum padi (Linné) (Homoptera: Aphididae) nymphs and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs at 21±1 °C and a photoperiod of 16:8 (L:D). After moulting, third and fifth instar nymphs and adults were placed in Petri dishes containing an abundant food source for 24 h. After 24 h, the food was removed and groups were randomly assigned to increasing periods of prey deprivation. Each D. lutescens nymph or adult was placed at the center of an empty arena and its searching path was recorded to calculate different path parameters and to determine the type of movement mode adopted. Results show an effect of starvation on both nymphal and adult D. lutescens searching paths. Satiated third instar nymphs manifested an intensive search path whereas fifth instar nymphs and adults adopted an intermediate one. When starved, the extensive search path appeared early in young nymphs, and later in the last instar nymphs and adults, according to the degree of prey deprivation.     

Oviposition behavior of Edovum puttleri, reared on two hosts, Leptinotarsa decemlineata and L. texana

Female Edovum puttleri Grissell [Hymenoptera: Eulophidae], reared from eggs of Leptinotarsa decemlineata (Say) or Leptinotarsa texana Schaeffer [Coleoptera: Chrysomelidae], were videotaped as they attacked egg masses of L. decemlineata containing 20 host eggs. We identified 15 components of ovipositional behavior. Parasitoids reared on L. texana attacked and oviposited in significantly more host eggs than did females reared on L. decemlineata. Ethometric analyses of behavioral transitions and a clustering analysis of 34 behavioral parameters showed that females reared on L. texana attacked the host egg mass in a different manner than those reared from L. decemlineata. It was concluded that differences were associated with the host species upon which they were reared. Contrary to previous reports, mortality of unparasitized hosts was caused by an ovipositor probe of short duration, which was not related to host-feeding.     

Discovery of a life history shift: precocious flowering in an introduced population of Prosopis

The genus Prosopis contains many valuable, long-lived, multi-purpose legume trees, some of which are also invasive species. The time of first flowering is important for increasing production of sweet, protein-rich pods in plantations, especially under short rotations, and affects the rate of spread as a weed. Trees generally begin flowering at 3–5 years of age. However, seedlings from a small seedlot collected from an introduced population in southern Mauritania were observed to begin flowering at 3–4 months after germination. This is unknown in the native range of any Prosopis species, and appears to represent a major evolutionary event triggered after naturalization. This paper reports a detailed investigation with seed collected from Aleg, Brakna region, Mauritania, in 1998 (Prosopis sp. ‘Aleg’). Two experiments were established, in glasshouses at Cirad, Montpellier, France, and Coventry University, UK. Flowering began at the two sites 104 and 169 days after sowing, respectively, and 97.5% of plants had flowered at Coventry after 306 days. Flowers produced abundant pollen with 50–60% viability indicated by FDA staining and 40–50% germination on an artificial medium. No pods were formed. All plants analysed were diploid. Morphologically, these juvenile plants were similar to American species of section Algarobia, and exhibited leaf characters typical of P. pallida. However, due to the large variation in morphology within this section of the genus, further studies are required to confirm the actual species. This is the first record of precocious flowering in Prosopis, and has been found only in a single, introduced population. Implications for genetic improvement of tropical Prosopis, and particularly the spread of these species as invasive weeds, are discussed. Such a life history shift in the increased reproductive ability of a species following introduction, with potentially significant environmental effects, may not be restricted to Prosopis and merits further detailed investigation.     

Biological studies of the predacious miteTyphlodromus pelargonicus a predator of the two spotted spider miteTetranychus urticae on cucumber plants [Acari: Phytoseiidae; Tetranychidae]

The predacious miteTyphlodromus pelargonicus El-Badry preyed on the different developmental stages of the two spotted spider miteTetranychus urticae Koch. The development was quickest and the number of prey consumed was highest when individuals were maintained on eggs compared with nymphs or adult female stages. The predator was able to develop and reproduce on the eriophyid miteEriophyes dioscoridis. Soliman & Abou-Awad, nymphs of the tobacco whiteflyBemisia tabaci (Genn.) and pollen grains ofPhoenix dactylifera andRicinus communis. The average number of eggs/♀/day was 1.4, 0.7, 1.2 and 0.9 on eriophyid, whitefly,Ph. dactylifera andR. communis respectively.      

Effects of sex and age of a dioecious tree, <Emphasis Type="Italic">Forchhammeria pallida</Emphasis> (Capparaceae) on the performance of its primary herbivore, <Emphasis Type="Italic">Murgantia varicolor</Emphasis> (Hemiptera: Pentatomidae)

The effects of sex and age of a dioecious tree, Forchhammeria pallida, on the survival and development of a Mexican harlequin bug, Murgantia varicolor, were examined. In the laboratory, bugs reared on fruits or fruits and leaves developed rapidly and had a high rate of survivorship, whereas bugs reared on leaves alone developed slowly after the second instar and died by the fifth instar. Murgantia varicolor showed a preference for leaves from juvenile plants over leaves from mature plants, and bugs reared on leaves from juvenile plants survived significantly longer than those reared on leaves from mature plants. Murgantia varicolor showed no preference for feeding on leaves of mature male versus mature female plants. In the field, M.varicolor occurred on male, female and juvenile plants. Although nymphs were less common on male than female F.pallida, their presence in substantial numbers shows that M.varicolor oviposits on both male and female plants. However, adult M.varicolor were rare on male plants. This result is supported by the inability of nymphs to complete their development on vegetative parts of F.pallida in the laboratory. These observations suggest that dioecy in F.pallida may be disruptive to populations of M.varicolor.     

Development and feeding of <Emphasis Type="Italic">Tetraphleps galchanoides</Emphasis>, a predator of the hemlock woolly adelgid

Tetraphleps galchanoides Ghauri (Hemiptera: Anthocoridae) nymphs were collected from hemlock woolly adelgid (HWA) Adelges tsugae Annand (Hemiptera: Adelgidae) infested Tsuga sp. in Baoxing, Sichuan, China. First and second stage nymphs collected from foliage shipped from China; were reared to adults and tested for feeding rates and host preferences. They were reared at 5, 8, 12, and 15 ± 1 °C from November to December, January to March, April, and May to June, respectively, in the quarantine laboratory at Virginia Polytechnic Institute and State University. At 8 °C, development time was 15, 20, and 40 days for the N-III, IV, and V nymphal stages, respectively. Adult males lived 83 days with a range of 21–147 days. A single adult female lived for 21 days. At 5 °C, second stage T. galchanoides nymphs consumed 0.8 HWA nymphs per day, and 2.0 HWA nymphs per day at the N-V stage. At 8 °C, consumption of HWA nymphs ranged from 1.3 to 3.4 nymphs per day for the N-III to N-V stages, respectively. Adult T. galchanoides consumed more HWA eggs than HWA adults, pine bark adelgid (PBA) Pineus strobi (Hartig) (Hemiptera: Adelgidae) adults, and eggs in no-choice tests. In choice tests with HWA eggs and PBA eggs, more HWA eggs were eaten. Adult and nymph body measurements are presented for determination of nymphal instars.     

Bottom-up Mediation of an Ant-Membracid Mutualism: Effects from Different Host Plants

The relationship between the membracid, Publilia modesta, and the tending ant, Formica obscuripes, was either a mutualism or commensalism depending on the host plant species. Experimental manipulation of the presence of ants in two different years indicated that the presence of ants had a positive effect on nymph numbers on both host plants, Chrysothamnus viscidiflorus and Wyethia spp. However, Wyethia spp. senesced before membracid nymphs reached adulthood, causing extensive mortality of membracids. In contrast, C. viscidiflorus plants senesced after nymphs had developed into adults. The increased number of nymphs in the presence of ants translated into more new adults on C. viscidiflorus, but not on Wyethia spp. Poor host plant choices may render the presence of ants irrelevant for such insects on some host plants. Being a host plant generalist may lead to significant variability in the outcomes of mutualistic interactions. Co-ordinating editor: N. Yamamura     

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.     

Effects of different Beauveria bassiana isolates on field populations of Lygus lineolaris in pigweed (Amaranthus spp.)

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is a pest of various fruit, vegetable, fiber, and seed crops; including cotton. Lygus spp. populations often build on alternate host plants before moving to cotton, and in the midsouthern U.S. wild host plants, such as pigweed (Amaranthus spp.), play a major role in L. lineolaris population development. Three isolates of the entomopathogenic fungus Beauveria bassiana (Balsamo) were evaluated for L. lineolaris control in redroot pigweed (Amaranthus retroflexus L.): one from L. lineolaris in Mississippi (TPB3); one from Lygus hesperus (Knight) in California (WTPB2); and one commercial isolate from Mycotrol^® (GHA). Fungal applications resulted in moderate to high mycosis in adults (33 to 80%) and moderate mycosis in nymphs (36 to 53%) that were collected from field plots at 2 days post-treatment and incubated under laboratory conditions. Although TPB3 was previously found to be more pathogenic in laboratory bioassays, there was not a consistent separation of this isolate from the other two isolates in field trials. Where differences in adult mycosis or mortality were observed, TPB3 was the most pathogenic. However, in one field trial 7 day mortality for nymphs treated with GHA was higher than those treated with TPB3 or WTPB2. Infection rates at 2, 7, and 14 days post-treatment from caged and non-caged adults suggested that movement of adults among plots occurred, which could have masked some treatment effects. Fungal treatments did not significantly reduce populations relative to controls. This may have been caused by delayed mortality rates under field conditions and/or difficulties with estimating population change under field conditions characteristic of wild host plant populations (e.g., heterogeneous populations, adult movement, and small plot size). Further work evaluating time–dose–mortality over dynamic temperatures, spring and fall field trials on this and other wild hosts, and improved methods for estimating populations on wild hosts are needed.     

A single species of plant predicts territory occupancy in a population of Peruvian Plantcutters

Habitat selection assessments at multiple spatial scales provide a more complete understanding of the habitat requirements of a species, a matter that is especially useful for managing endangered wildlife. Studies of the diet and population distribution of threatened Peruvian Plantcutters (Phytotoma raimondii) suggest that the presence of Prosopis spp. trees, and the shrubs Grabowskia boerhaaviaefolia and Scutia spicata could explain the scattered distribution of their remnant subpopulations. However, our overall understanding of this remains unclear and incomplete because plantcutters are often absent in areas dominated by Prosopis spp., and other species of plants have largely been overlooked in distribution models. One way to address this issue is to also investigate spatial distribution patterns at finer scales within subpopulations. We modeled the probability of territory occupancy at one of their last strongholds, the Pómac Forest Historical Sanctuary in Peru. Our predictors were defined by biotic interactions using data collected in 2015 and 2016, and previous studies of their diet. We found that Peruvian Plantcutters consumed the leaves, fruits, and flowers of at least nine species of plants, but only G. boerhaaviaefolia shrubs, and the trees Prosopis spp. and Colicodendron scabridum were used more than expected based on availability. We did not observe consumption of S. spicata, but this plant was rare. Territory occupancy was positively influenced only by the availability of G. boerhaaviaefolia, a plant used by Peruvian Plantcutters both as a source of food and nest material. Our results suggest that, despite their diverse diet, Peruvian Plantcutters can be particularly dependent on the availability of G. boerhaaviaefolia. Accordingly, this may explain why both co-occur in most subpopulations. Lastly, although we found that Prosopis spp. did not explain territory occupancy, previous research shows that it does explain their distribution on a broader scale (across subpopulations). This inconsistency across spatial scales suggests a potential key role of Prosopis spp. in guaranteeing dispersal between and connectivity among subpopulations.     

Absorption and cannibalism: do phytoseiids conserve egg resources when prey densities decline rapidly?

The number of eggs oviposited or left in the opisthosomas of dead mites (total eggs) was assessed for Metaseiulus occidentalis (Nesbitt), Neoseiulus fallacis (Garman), Typhlodromus pyri Scheuten or Amblyseius andersoni Chant when each was caged with either (1) no Tetranychus urticae Koch, (2) only odours of T. urticae, (3) ten eggs of M. occidentalis or (4) ten nymphs of M. occidentalis (T. pyri for M. occidentalis). The total eggs for the no prey versus odour tests did not differ within species; the levels were the greatest for N. fallacis > T. pyri > A. andersoni > M. occidentalis. Among treatments, egg means did not differ for M. occidentalis but they did for N. fallacis and T. pyri and similar trends were seen for A. andersoni. Egg means were usually less for mites held with ten predator nymphs than mites held with ten predator eggs or with no prey. Were adult females with nymphs absorbing rather than ovipositing their eggs or dying with them in their opisthosomas? Activity levels (walking) for adult females were no more for mites held with nymphs versus no food. The data indicated that interference by nymphs was not increasing the energy use of females and thus reducing egg levels. However, tests with ten nymphs, one egg and no adult female had egg losses from nymphal predation that could account for fewer eggs in cage tests. Overall, no evidence for absorption was found. If it occurs, it must be among younger eggs or mites exposed to less rapid prey losses than were the mites tested here; in addition, other stimuli may cause absorption. The total eggs in sticky-tape tests were greatest for N. fallacis > M. occidentalis > T. pyri > A. andersoni. Cage versus stick-tape data differed most for M. occidentalis because of cannibalism. All four mites cannibalized eggs but M. occidentalis did most rapidly and extensively. When starved, it laid all of its eggs before the other three species did. Such behaviours may enhance survival of M. occidentalis when prey become scarce.     

Ontogeny of prey selection inSirthenea carinata: Generalist juveniles become specialist adults

Prey selection bySirthenea carinata (F.) [Hemiptera: Reduviidae] was investigated using both field captured and laboratory-reared nymphs and adults. Small nymphs (instars 1–3) showed no preference for mole crickets [Orthoptera: Gryllotalpidae: Scapteriscus] as prey overGryllus spp. orAnurogryllus muticus (De Geer) [Orthoptera: Gryllidae]. Larger nymphs (4th and 5th instars) and adults showed a significant preference for mole crickets in the same sort of choice experiments, choosing mole crickets 84% of the time. Laboratory hatchedSirthenea nymphs matured faster on a mixed diet ofGryllus spp.,A. muticus, andScapteriscus spp. Than did siblings fed a diet ofGryllus spp. alone, but no differences were found in size or duration of individual stadia between the diet groups.      

Can the Geranium Bronze, <Emphasis Type="Italic">Cacyreus marshalli</Emphasis>, become a threat for European biodiversity?

Cacyreus marshalli Butler is an invasive species in many parts of Europe and Mediterranean area. In Europe, its larvae normally feed on pelargoniums. We investigated its potential to spread to native Geranium spp. and evaluated the conservation risks that such a shift would pose for both native geraniums and cohabitant butterflies. The host plant preferences of the Geranium Bronze were investigated under controlled conditions. Studies included both no-choice and multi-choice tests, respectively using 9 and 6 Italian native Geranium spp. Host plant preferences were evaluated by counting the number of eggs laid on individual plants and following butterfly development until adult emergence. Under no-choice conditions, at least one egg was recorded on each tested plant, except for G. phaeum L. All the plants on which oviposition occurred were fully suitable for larval development. The butterfly, however, clearly preferred three species, i.e. G. pratense L., G. sanguineum L. and G. sylvaticum L. for oviposition. In multi-choice trials, females laid at least one egg on all the tested plants, with a preference for G. pratense and G. sylvaticum. In presence of Pelargonium spp. plants, however, no oviposition was observed on any Geranium spp. We assessed offspring fitness measuring their wingspan. No statistical differences were detected in the wingspan between adults emerged from Geranium and Pelargonium. Cacyreus marshalli represents a potential threat for both native geraniums and for Geranium-consuming lycaenids, such as Aricia nicias Meigen and Eumedonia eumedon Esper.     

Interaction between Podisus maculiventris and Harmonia axyridis two predators used in augmentative biological control in greenhouse crops

Intraguild predation (IGP) betweenthe pentatomid Podisus maculiventris(Say) and the coccinellid Harmoniaaxyridis (Pallas) in the absence or presenceof the extraguild prey Spodopteralittoralis (Boisduval) and Myzuspersicae (Sulzer) was studied in thelaboratory. Interactions were asymmetric infavor of the pentatomid. Podisusmaculiventris readily fed upon eggs and larvaeof H. axyridis, but adult beetles wererarely attacked. Success of attacks by P.maculiventris was stage dependent, fourthinstars and adults being more successful inkilling ladybeetle larvae than second instars.Attacks by H. axyridis on the pentatomidwere rare and none of them were successful. Theeffect of introducing extraguild prey on thelevel of IGP was tested both in petri dishesand on caged sweet pepper plants. Whensufficient numbers of S. littoralislarvae were present to satiate the pentatomid,predation on H. axyridis larvae decreasedsignificantly, indicating that the coccinellidis a less preferred or less vulnerable prey.When the aphid M. persicae was presentedas extraguild prey, levels of IGP were notaltered. Nymphs of P. maculiventrissuccessfully completed development whenexclusively fed on larvae of H. axyridis,but developmental time was longer than onlepidopteran prey. No pentatomid nymphs reachedadulthood on aphids alone. IGP by P.maculiventris on H. axyridis may be ofsome importance in greenhouse crops, where bothpredators are being used increasingly inaugmentative biological control programs.Nonetheless, it is expected that in practicelarger larvae and adults of H. axyridiswill escape most attacks by the pentatomid.     

Functional response ofCurinus coeruleus (Col.: Coccinellidae) toHeteropsylla cubana (Hom.: Psyllidae) on artificial and natural substrates

Laboratory measurements of the functional response of adultCurinus coeruleus (Mulsant) to nymphs ofHeteropsylla cubana Crawford on filter paper and on leaves of different host plants showed a significant effect of these different substrates on nymph consumption at several different densities. Moreover, this effect may be explained by the influence of the substrate on the search rate of the predator. Host plants tested includedLeucaena leucocephala (Lam) de Witt,L. diversifolia (Schlecht.) Benth. andL. pallida Britton and Rose. Results obtained may be relevant to plant-protection research programs involving the integration of biological control with host-plant resistance.      

Hyperparasitism by Mesochorus spp. (Hymenoptera: Ichneumonidae) in Peristenus sp. (Hymenoptera: Braconidae) and development of PCR primers for hyperparasitoid detection

Peristenus sp. pupae collected from Lygus spp. nymphs in 2001 and 2002 were over-wintered in the laboratory. In both years, more than 30% of adults emerging from over-wintering pupae were identified as ichneumonid hyperparasitoids, Mesochorus curvulus Thomson and Meschorus sp. (Hymenoptera: Ichneumonidae). At the end of the over-wintering period, Peristenus sp. males emerged first followed by Peristenus sp. females and finally Mesochorus spp. The male:female ratio in emerging Peristenus sp. adults was skewed towards males. The Internal Transcribed Spacer (ITS) region and the cytochrome oxidase I (COI) gene from Mesochorus spp. were sequenced. ITS sequences were used to develop PCR primers to detect Mesochorus spp. hyperparasitism in the primary host, Lygus spp. PCR analysis of field-collected Lygus spp. nymphs gave similar estimates of Mesochorus spp. hyperparasitism to the rearing protocols (25–28%). Sequence analysis of COI and ITS regions and subsequent restriction endonuclease analysis of ITS PCR products from Mesochorus spp. indicate the presence of two genotypes in the population. The possibility that these two genotypes represent separate or cyrptic species is discussed.