Natural Biological Control and Key Mortality Factors of Diaphania hyalinata (Lepidoptera: Pyralidae) in Cucumber

Key mortality factors due to natural biological control of the melonworm, Diaphania hyalinata, were investigated. Mortality factors were quantified in cucumber plots and used to develop a life table. The highest mortality of the melonworm took place during the egg stage (90.08% mortality) when the most important mortality factor was the predator Paratrechina sp. (Hymenoptera: Formicidae). However, the critical mortality stage of this insect pest was the fifth larval instar and its key mortality factor was parasitism by tachinid flies (aff. Amazohoughia, Eucelatoria sp. and aff. Lixophaga).     

Mortality Dynamics of Spodoptera frugiperda (Lepidoptera: Noctuidae) Immatures in Maize

We characterized the dynamics of mortality factors affecting immature developmental stages of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Multiple decrement life tables for egg and early larval stages of S. frugiperda in maize (Zea mays L.) fields were developed with and without augmentative releases of Telenomus remus Nixon (Hymenoptera: Platygastridae) from 2009 to 2011. Total egg mortality ranged from 73 to 81% and the greatest egg mortality was due to inviability, dislodgement, and predation. Parasitoids did not cause significant mortality in egg or early larval stages and the releases of T. remus did not increase egg mortality. Greater than 95% of early larvae died from predation, drowning, and dislodgment by rainfall. Total mortality due to these factors was largely irreplaceable. Results indicate that a greater effect in reducing generational survival may be achieved by adding mortality to the early larval stage of S. frugiperda.     

Quantitative assessment of biotic mortality factors of the European corn borer (Lepidoptera: Crambidae) in field corn.

Five treatments were used to exclude naturally occurring predators and parasitoids, based on body size and flight ability, to assess their effect on Ostrinia nubilalis (Hübner) populations on corn plaits. Two initial O. nubilalis egg densities (one egg mass and three egg masses per plant) were assigned to each treatment. Egg predation was higher in uncaged treatments than in caged treatments. Flying insect predators, primarily Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae), reduced egg densities by 50%. Thirty-five to 84% of O. nubilalis larvae were infected with Nosema pyrausta (Paillot) (Microspora: Nosematidae). The incidence of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes), ranged from 0 to 21%, whereas larval parasitism, mainly by Macrocentrus cingulum Reinhard (Hymenoptera: Braconidae) ranged from 0 to 31%. In contrast to previous studies, this 3-yr field study documents that egg predation and larval infections of O. nubilalis were significant and consistent biotic mortality factors.     

Adaptation of indigenous larval parasitoids to Tuta absoluta (Lepidoptera: Gelechiidae) in Italy

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a serious threat to tomato (Solanum lycopersicum L.) crops in South America. In Europe, after its first detection in Spain in 2006, it rapidly spread through the Mediterranean basin, reaching Italy 2 yr later. The aim of our work was to find indigenous effective biological control agents and to evaluate their potential role in the control of larval populations of T. absoluta in controlled conditions. Nine species of larval parasitoids emerged from field-collected tomato leaves infested by T. absoluta. The most abundant, Necremnus near artynes (Walker) and Necremnus near tidius (Walker) (Hymenoptera: Eulophidae), were tested in laboratory parasitism trials. Furthermore, because the species N. artynes and N. tidius are each reported in literature as an ectoparasitoid of Cosmopterix pulchrimella Chambers (Lepidoptera: Cosmopterigidae) on upright pellitory plants, olfactometer bioassays were performed to assess the response of our parasitoids to the odors of tomato and pellitory leaves infested by T absoluta and C. pulchrimella, respectively, compared with healthy ones. Both Necremnus species showed good adaptation to the invasive pest, and we observed a high larval mortality of T. absoluta because of host feeding and parasitism. Even olfactory responses highlighted a preference of both wasps for tomato plants infested by the exotic pest. These preliminary results demonstrated a high suitability of these indigenous natural enemies for controlling T. absoluta. Further investigations are needed to confirm their role as potential biological agents in commercial tomato plantations.     

Natural mortality factors of Leucoptera coffeella (Lepidoptera: Lyonetiidae) on Coffea arabica

The natural mortality of the coffee leafminer, Leucoptera coffeella (Guérin-Méneville) was investigated in three strata of coffee plant canopy for three seasons through construction and analysis of ecological life tables. Mortality of the leafminer was similar on all thirds of the canopy. Total mortality of immature stages was 95%, with 38.5, 43.8 and 12.7% occurring during egg, larval, and pupal stages. Rainfall killed 39.3% of eggs and larvae, and together with egg inviability (16.3%) and Vespidae (11.3%), were the highest mortality factors. Six wasp parasitoids caused 8% of larval mortality. Egg and larva were the critical stages. Variation in mortality was primarily associated with egg inviability, rainfall, and parasitism by Horismenus sp. (Hymenoptera: Eulophidae). Physiological disturbances during molting and metamorphosis also contributed for fluctuations in mortality of the leafminer. Tactics of integrated pest management to enhance natural mortality of the leafminer while conserving or augmenting the action of natural enemies are discussed.     

Non-target parasitism of the endemic New Zealand red admiral butterfly (Bassaris gonerilla) by the introduced biological control agent Pteromalus puparum

The New Zealand red admiral butterfly, Bassaris gonerilla (F.) (Lepidoptera: Nymphalidae), has been known as a non-target host for the introduced biological control agent Pteromalus puparum (L.) (Hymenoptera: Pteromalidae) for at least 35 years, but the level of parasitism has never been quantified. Pre-imaginal mortality in B. gonerilla was assessed over the southern summer of 2000/01 at six field sites in the Christchurch area of the South Island, New Zealand. Individual eggs and larvae were identified by tagging the stem of the Urtica ferox Forst.f. plant on which they were found and the fate of these individuals was checked weekly. These data were used to construct a partial life table for B. gonerilla. Egg mortality was very high (95%), with parasitism by an unidentified Telenomus sp. Haliday (Hymenoptera: Scelionidae) causing 57% mortality. Mortality in the larval and pupal stages increased at a constant rate with age and the major mortality factor was disappearance, which was assumed to be a result of predation and dispersal of larvae. The introduced biological control agent P. puparum parasitized 14% of B. gonerilla pupae sampled. However, parasitism by another exotic parasitoid, the self-introduced Echthromorpha intricatoria (F.) (Hymenoptera: Ichneumonidae), was even higher at 26%. A survey of pupal parasitism in three regions of New Zealand (Wellington, Christchurch, and Dunedin) revealed overall parasitism levels of 67% by E. intricatoria and 8% by P. puparum, but due to the difference in emergence times of B. gonerilla and its parasitoids, these are likely to be overestimates of percent parasitism. It is concluded that P. puparum has permanently enhanced mortality in B. gonerilla, but the level of mortality is low relative to egg parasitism by Telenomus sp., larval disappearance mortality, and pupal mortality due to E. intricatoria parasitism. To determine if this level of pupal parasitism has had population effects will require more data and the development of a population model for B. gonerilla.     

Interactions between the egg and larval parasitoids of a gall-forming midge and their impact on the host

1. The gall‐forming midge Rhopalomyia californica was exposed experimentally to parasitism and predation during only the egg stage, during only the larval stage, during neither stage, or during both stages. 2. The combined action of natural enemies that attack during both the egg stage and the larval stage led to the lowest number of midges and total insects (midges + parasitoids) in the next generation, and the highest percentage parasitism. 3. The larval parasitoid killed a large fraction of hosts without producing new parasitoid offspring, while there is some indication that the egg parasitoid on its own tended to produce the most parasitoid offspring. The contrasting implications of host mortality versus parasitoid production for biological control are discussed. 4. Exposure to larval parasitoids resulted in a reduction in the number of egg parasitoid offspring produced, but exposure to the egg parasitoid did not affect the number of larval parasitoid offspring produced significantly.     

Mortality factors affecting Bemisia tabaci populations on cotton in Turkey

Cohort‐based, partial life tables were constructed to determine the sources and rates of mortality factors affecting Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on cotton in the eastern Mediterranean region of Turkey over a two year period. Mortality factors were recorded as due to predation, parasitism, dislodgement and unknown for five developmental stages. Across 10 independent cohorts, the highest median rate of marginal mortality pooled over all stages was attributed to parasitism (0.69) followed by predation (0.67). The key factor was hypothesized to be parasitism based on graphical and regression‐based comparison of individual factor k‐values to total generational mortality. The greatest amount of marginal immature mortality occurred during the fourth nymphal stadium (median = 0.77) and mortality during this stage was also most predictive of variation in total mortality. Pooled over all developmental stages, the highest rates of irreplaceable mortality were associated with parasitism (median: 0.112), followed by predation (0.088), dislodgement (0.020) and unknown (0.017). Although crawler mortality was not explicitly measured, sensitivity analyses indicated that mortality during this stage would have changed total mortality by only 0.45–1.21% and had no effect on identification of key factors. There was no significant effect of cotton cultivar on any mortality factor or total mortality over the two years of study. Results suggest that conservation of natural enemies, particularly parasitoids, may provide for more sustainable management of B. tabaci on cotton in Turkey.     

Seasonal variation in natural mortality factors of Tuta absoluta (Lepidoptera: Gelechiidae) in open‐field tomato cultivation

The seasonal variation in natural mortality of phytophagous insects is determined by the relative importance of biotic and abiotic factors in agroecosystems. Knowledge regarding these factors throughout the year represents a key concern for IPM programmes. Seasonal population fluctuations of tomato pinworm, Tuta absoluta, led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. The aim of this study was to verify the seasonal variation in T. absoluta mortality factors in tomato crops. Immature stages of T. absoluta were obtained from laboratory‐rearing in the laboratory. These were taken to the field and monitored over two years. The mortality causes for each stage of insect development from egg to adult were assessed daily. Multiple biotic and abiotic mortality factors affected the immature T. absoluta stages such as rainfall, physiological disturbances, diseases, parasitoids and predators. The key T. absoluta mortality factor during summer–spring was predation. In addition, larvae predation correlated positively with temperature, wind velocity, photoperiod and rainfall. Nevertheless, during winter–fall, the key mortality factor was parasitism. Therefore, the critical stage for mortality was 3rd‐ and 4th‐instar larvae, being more vulnerable to natural control factors. Finally, the results showed the importance of vertical and horizontal action on natural mortality factors.     

The impact of exotic parasitoids on populations of a native Hawaiian moth assessed using life table studies

The impact of alien species on native organisms is a cause for concern worldwide, with biological invasions commonplace today. Suppression efforts targeting many invasive species have included introductions of biological control agents. The numerous releases of biological control agents in the Hawaiian archipelago have resulted in considerable concern for non-target impacts, due to high levels of non-target parasitism observed to occur in some cases. This study investigated the impact of introduced Hymenoptera parasitoids on a Hawaiian moth. The endemic Hawaiian moth Udea stellata (Butler) has seven alien parasitoids associated with it, two purposely introduced, three adventive, and two of uncertain origin. The objective of this study was to determine the relative contribution of the seven parasitoid species to the population dynamics of U. stellata by constructing partial life tables. Marginal attack rates and associated k-values were calculated to allow comparison of mortality factors between experimental sites. Sentinel larvae were deployed on potted host plants and left in the field for 3-day intervals in open and exclusion treatments. The factors that contributed to total mortality in the open treatment were: disappearance (42.1%), death due to unknown reasons during rearing (16.5%) and parasitism (4.9%). The open treatment incurred significantly higher larval disappearance compared to the exclusion treatment (7.8%), which suggests that in large part disappearance is the result of predation. Adventive parasitoids inflicted greater total larval mortality attributable to parasitism (97.0%) than purposely introduced species (3.0%).     

Development of methods for the field evaluation of Oobius agrili (Hymenoptera: Encyrtidae) in North America,a newly introduced egg parasitoid of the emerald ash borer (Coleoptera: Buprestidae)

A field study was conducted in forested plots near Lansing, Michigan in 2008 and 2009 to evaluate the newly introduced egg parasitoid Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) for control of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). To measure parasitism by O. agrili, laboratory-reared “sentinel EAB eggs” were deployed under bark flaps on trunks of selected ash trees in both parasitoid-release and non-release control plots. In addition, naturally occurring EAB eggs were collected in both parasitoid-release and control plots to measure parasitism. While no parasitism was detected with either sentinel or naturally occurring EAB eggs in control plots in either 2008 or 2009, a low level of parasitism by O. agrili was detected in the parasitoid-release plots in both artificially deployed sentinel eggs (?1%) and field-collected, naturally occurring eggs (1.1–4.2%) in both years. In addition to losses due to parasitism by O. agrili, a large proportion (37–52%) of the field-deployed sentinel eggs disappeared, possibly due to predators such as ants, in both parasitoid-release and control plots. While no statistical differences in parasitism by O. agrili were detected between parasitoid release and control plots, other sources of egg mortality such as disappearance due to predation on eggs, varied significantly across study sites in both 2008 and 2009. The relevance of these findings to future release and evaluation strategies for O. agrili for biological control of the invasive emerald ash borer in the US is discussed.     

The Influence of Egg Parasitoids Belonging to the Telenomus busseolae (Hymenoptera: Scelionidae) Species Complex on Sesamia calamistis (Lepidoptera: Noctuidae) Populations in Maize Fields in Southern Benin

During the second cropping season of 1992, maize fields in southern Benin were examined twice at the pre-tasselling stage, to assess the abundance of eggs of Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and egg parasitism by Telenomus busseolae Gahan (Hymenoptera: Scelionidae). They were also examined at harvest, to investigate the impact of egg parasitism early in the season on S. calamistis populations, and thus plant growth. S. calamistis eggs were found in 84.0% of the fields and on 16.8% of the plants. The parasitoid was present across the entire survey area, with the rate of egg parasitism averaging 76.4%. On average, 84.1% of the egg masses/field were parasitized, indicating that the parasitoid had a good capacity for searching. The relationship between parasitization rates and egg batch size was best described by a quadratic function, with maximum parasitism of about 95% between 1 and 25 eggs/batch. In a multiple regression analysis involving infestation levels at harvest, and soil and parasitoid variables, the T. busseolae parasitization rate was one of the major factors influencing S. calamistis densities. The yield loss due to S. calamistis decreased with increasing egg parasitism.     

Role of canopy height in the resistance of Lycopersicon hirsutum f. glabratum to Tuta absoluta (Lep., Gelechiidae)

The objective of this work was to study the effect of plant canopy height on the resistance of the tomato species Lycopersicon hirsutum to the tomato leafminer Tuta absoluta . Determination of the levels of tridecan-2-one (2-TD) and undecan-2-one (2-UD) in L. hirsutum , as well as the leaf area, density and types of trichomes present in L. hirsutum and L. esculentum were made on apical, medium and basal parts of plant canopy. Correlation of these data were made with the following biological characteristics of T. absoluta : rates of oviposition and egg hatching; length of egg, larval and pupal stages; mortality of the larval and pupal stages; pupal weight; and sex ratio. Levels of 2-TD on leaves of L. hirsutum increased from bottom to top of canopy. Tuta absoluta had higher oviposition and egg hatching, as well as lower mortalities and smaller larval and pupal periods in L. esculentum than in L. hirsutum . Longer pupal period and greater number of small and large mines of T. absoluta were verified in the apical and medium parts of L. hirsutum plants. On the other hand, higher pupal mortality and longer larval periods were obtained in the apical and basal parts of the L. hirsutum plants. Larval mortality was higher in the basal part of those plants. In L. esculentum , leaves from the apical part of the plant promoted lower mortality, longer larval period and greater number of large mines of T. absoluta . However, a shorter pupal period was verified on leaves of the basal part. It appears that an increase in glandular trichome density in L. hirsutum leads to an increase in the levels of 2-TD, which, in turn slows down larval development.     

Efficacy of Trichogramma wasps for controlling tomato leaf miner Tuta absoluta

Tomato is considered as one of the most essential vegetables after potato in Egypt. Tomato is infested by many insects; one of these serious insects is tomato leaf miner Tuta absoluta, which causes yield losses up to 100%. T absoluta is attacking leaves, flowers, stems and fruits. Trichogramma species is playing an important role in reducing this insect infestation. Efficiency of Trichogramma evanescens alone and in combination with insecticides were assessed against T. absoluta in tomato fields. Three release rates 500, 1000 and 1500 parasitized egg/card as well as 2 insecticides (Dimilin and Corgen) were applied. Number of normal and parasitized eggs, live and dead larvae and tunnel numbers were recorded. The results revealed that T. absoluta eggs were higher in control plots than those counted in Trichogramma plots. Among Trichogramma release rates, higher release rates, obtained higher parasitism rates of Tuta eggs (reached to 50%). Companying Trichogramma with IGR Dimilin had a little side effect on parasitism rate which it was smaller compared to plots of Trichogramma alone. Dimilin (IGR) caused reducing in Tuta larval population, which it differed significantly compared to control plots. Another IGR, Coragen resulted increasing the mortality of Tuta larvae than other treatments. In Trichogramma release rates, higher release rates, lower number of tunnels were found. In plots of companying Trichogramma with Coragen, the lowest tunnel numbers were recorded. Field release of T. evancences would be a promise biocontrol agent to suppress T. absoluta. These findings may encourage using T. evancences as a favorable strategy for integrated management of T. absoluta to produce safe tomato.     

Life tables of the processionary caterpillar Ochrogaster lunifer Herrich-Schäffer (Lepidoptera: Thaumetopoeidae) at local and regional scales

A major ongoing debate in population ecology has surrounded the causative factors underlying the abundance of phytophagous insects and whether or not these factors limit or regulate herbivore populations. However, it is often difficult to identify mortality agents in census data, and their distribution and relative importance across large spatial scales are rarely understood. Here, we present life tables for egg batches and larval cohorts of the processionary caterpillar Ochrogaster lunifer Herrich-Schäffer, using intensive local sampling combined with extensive regional monitoring to ascertain the relative importance of different mortality factors at different localities. Extinction of entire cohorts (representing the entire reproductive output of one female) at natural localities was high, with 82% of the initial 492 cohorts going extinct. Mortality was highest in the egg and early instar stages due to predation from dermestid beetles, and while different mortality factors (e.g. hatching failure, egg parasitism and failure to establish on the host) were present at many localities, dermestid predation, either directly observed or inferred from indirect evidence, was the dominant mortality factor at 89% of localities surveyed. Predation was significantly higher in plantations than in natural habitats. The second most important mortality factor was resource depletion, with 14 cohorts defoliating their hosts. Egg and larval parasitism were not major mortality agents. A combination of predation and resource depletion consistently accounted for the majority of mortality across localities, suggesting that both factors are important in limiting population abundance. This evidence shows that O. lunifer is not regulated by natural enemies alone, but that resource patches ( Acacia trees) ultimately, and frequently, act together to limit population growth.     

Density dependence and regulation in the systemNezara viridula (L.) (Hemiptera: Pentatomidae), host andTrichopoda giacomellii (Blanchard) (Diptera: Tachinidae), parasitoid

Summary The system formed byN. viridula and its almost specific parasitoidT. giacomellii has been studied in the Buenos Aires province, Argentina for 26 generations of the former and 20 generations of the latter. An intensive study over 9 host generations and key factor analysis made possible the identification and quantification of different mortality factors. The main factors determining the fluctuations in total generation mortality were: egg mortality due mainly to parasitism byT. basalis; nymphal predation on 1^st, 2^nd and 3^rd instar nymphs and migration; and adult mortality and reduction on potential natality due to parasitism byT. giacomellii. Adult mortality and reduction of potential natality, due to parasitism byT. giacomellii, was density dependent. This factor is capable of maintaining the simulations generated by a simple model based on key factor analysis, within the range of observed densities. These results suggest that parasitism byT. giacomellii can regulate the population, even in a small area of 450 m².     

Preliminary life table of the spotted tortoise beetle,Aspidomorpha miliaris (Coleoptera: Chrysomelidae) in Sumatra

From December, 1981 to February, 1982, a population study of the spotted tortoise beetle, Aspidomorpha miliaris, feeding on a shrub-like morning glory, Ipomea carnea, was conducted in Padang, Sumatra with the construction of a life table.

1. Dissection of oothecae collected from the field after hatching clarified that the average egg mass size was 43.4 and hatching rate was 25.0%. Causes for egg mortality included: parasitism by a wasp, Tetrastichus sp. A(Europhidae) (49.8% of eggs laid), predation (12.8%), disappearance of egg masses (5.3%) and hatching failure (7.1%). An ant, Dolichoderus bituberculatus, visiting the extrafloral nectaries of the host plnts was responsible for predation and disappearance of the egg masses. The ants again attacked the larvae and pupae.
2. Larvae showed a gregarious habit for almost the entire larval period. Survival rates between two successive instars were low and constant, ranging from 70 to 90%, but only 1.3% of final (5th) instars become pupae (six individuals). Since the growth of host plants was extremely rapid, shortage of food was rare in larval stages. The sudden drop in numbers after 5th instar may be due to predation and/or dispersal of matured larvae from the host plants for pupation.
3. Pupae were attacked by three species of parasitic wasps:Tetrastichus sp. C, Pediobius elasmi (Eulophidae) and Cassidocida aspidomorphae (Tetracampidae). Among the six pupae, two were parasitized, one died of disease and two disappeared. Out of 4078 eggs laid, only one emerged to adult.

     

Trade-offs in host use by Manduca sexta: plant characters vs natural enemies

There are two principal native host plants for the sphingid moth Manduca sexta L. in south eastern Arizona: Datura wrightii (Solanaceae), and the more recently reported, nonsolanaceous host, Proboscidea parviflora (Martyniaceae). A comparative study on causes and rates of mortality was conducted, since this provided a "natural experiment" for examining potential trade-offs in host use. The field data identified a dramatic trade-off between plant quality and predation. D. wrightii appears to provide a high quality food source in growth experiments, and eggs laid on its leaves hatch at high rates. The eggs and larvae, however, underwent extremely high levels of predation and parasitism in the field, and fewer than 0.5% reached the final larval stage. Eggs laid on P. parviflora , on the other hand, suffered low levels of predation and virtually no parasitism, but many eggs did not hatch due to developmental abnormalities induced by the plant, while a large proportion of larvae died after a few days of feeding. Overall, 3% of the eggs reached the final stage on this plant. The maintenance of the two host plants cannot be explained by single factors, but rather by the outcome of multiple factors on the insect fitness, including plant quality, suitability for egg development, predation risk, plant availability and competition with other herbivores. Our data emphasize the importance of predation in shaping host-plant ranges and support the idea of host-specific predation rates and "enemy-free" space.     

Impact of natural enemies on coffee leafminer Leucoptera coffeella (Lepidoptera: Lyonetiidae) population dynamics in Chiapas, Mexico

Coffee leafminer, Leucoptera coffeella, is a pest in many New World coffee growing areas. Previous studies suggested that its population dynamics were strongly affected by natural enemies, particularly of larvae, and physical environmental conditions. Our study documented through field surveys and life table analyses (i) the natural enemy complex associated with coffee leafminer and (ii) the impacts of natural enemies on the population dynamics of coffee leafminer, on coffee (Coffea arabica) at two elevations and two rainfall levels in the Soconusco region of Chiapas, Mexico. Twenty-two larval parasitoid species (including 14 morphospecies) were collected. Egg and pupal parasitoids were not recovered. Life table analyses showed that parasitism contributed 10% of real mortality, and parasitism rates were 8–10-fold higher at the low (<550 m) versus high (>950 m) elevation; parasitism rates were similar under low (<100 mm) and high (>400 mm) rainfall. Seventeen predator species (including five morphospecies) were collected, of which most were ants (Formicidae, 14 species) that contributed >58% of real mortality. Life table analyses showed that predation rates were higher at high versus low elevation and under high versus low rainfall. Independently of elevation and rainfall, egg predation (likely by ants) was the most important source of indispensable mortality (range = 0.13–0.30), except at low elevation and high rainfall where pupal predation (=0.14) was similarly important. Also, predation was the main source of coffee leafminer larval and pupal mortality during a 13-month period in a low elevation coffee farm and was highest during the rainy season (>400 mm rainfall/month), when coffee leafminer prevalence was highest. Overall, predation of eggs and pupae (the latter particularly at low elevation), mostly by ants, were the most important sources of coffee leafminer mortality. Because ants were the main source of coffee leafminer egg and pupal mortality, their importance and potential role in coffee pest management strategies were discussed.     

Effects of shelf architecture and parasitoid release height on biological control of Plodia interpunctella (Lepidoptera: Pyralidae) eggs by Trichogramma deion (Hymenoptera: Trichogrammatidae)

The effects of shelving type, packaging, and release height on success of Trichogramma deion Pinto & Oatman (Hymenoptera: Trichogrammatidae) parasitizing Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) eggs was studied under laboratory conditions. In trials on multipletiered gondola-type or open shelving units, with or without packaging, foraging success was evaluated by comparing parasitism and total mortality rates of sentinel egg disks among shelves after a single point-release of T. deion. Results showed that T. deion parasitized more egg disks and killed more total eggs on open shelves than on gondola shelving. The presence of packaging had no effect on parasitoid foraging on open shelves; however, packaging did interfere with parasitism of P. interpunctella eggs on gondola shelving. Egg parasitism and mortality patterns among shelves were not as evenly distributed on gondola-type shelving compared with open shelving. On gondola shelves without packages, changing the release point of T. deion from the middle to the lowest shelf shifted the distribution of parasitism toward the floor. Gondola shelving, especially in the presence of packaging, reduced foraging efficiency of T. deion for P. interpunctella eggs. Thus, to attain adequate control of P. interpunctella, it may be necessary to use two release heights on gondola shelving.