Emergence Of Adult Insects Research Articles

Improving quality of stored Trichogramma evanescens (Hymenoptera: Trichogrammatidae) by inducing diapause or quiescence

BackgroundEfficacy of parasitic wasps from the genus Trichogramma to attack the eggs of numerous important pests in various agricultural crops makes them one of the most prevalent biocontrol agents. In Trichogramma, the pre-pupal stage can survive during the cold season in a dormant state (diapause or quiescence). The optimal conditions for the induction of this pause of development during mass rearing to store the parasitoid for a long time in good quality depend on the species. In the present study, four factors [the incubation periods (24 and 48 h), diapause induction temperatures (9 and 11 °C), durations of the diapause induction (from 0 to 6 weeks), and the periods of storage (from 0 to 6 months)], were experimented to force Trichogramma evanescens Westwood, reared on Sitotroga cerealella, to enter diapause or quiescence and estimating their impacts on the efficacy of stored parasitoid.ResultsResults confirmed that the life parameters of T. evanescens as the percentage of adult emergence, female percentage, rates of wing deformation of emerged adults, and fecundity of emerged females were significantly affected by all experimented factors. The pre-storage treatments made it possible to store the parasitoid for at least 2 months at 3 °C, with no much changes in their fitness, the emergence rate of adults reached more than 80%, and the egg-laying efficacy of females reached more than 42 eggs per emerged female, when diapause induction treatments were applied for 5 weeks at 11 °C after 24 h of incubation. Furthermore, there is the possibility of storage for 6 months with an acceptable level of parasitoid’s quality, when diapause induction treatments were applied for 5 weeks at 9 °C after 24 h of incubation, the emergence rate reached 70%, and the number of eggs per female was 52 eggs, while no emergence of adult insects was recorded after 3 months of cold storage without diapause induction treatments.ConclusionTwo storage programs were reached for T. evanescens (depending on the adult emergence rate and fecundity of emerged females). There is a long-term storage (6 months), when diapause was induced at a low temperature (9 °C) after 24 h of incubation. Short-term storage (from 2 to 4 months), when quiescence was induced under a higher temperature of 11 °C after both 24 and 48 h of incubation.

The impact of radiofrequency exposure on Aedes aegypti (Diptera: Culicidae) development.

Wireless communication connects billions of people worldwide, relying on radiofrequency electromagnetic fields (RF-EMF). Generally, fifth-generation (5G) networks shift RF carriers to higher frequencies. Although radio, cell phones, and television have benefitted humans for decades, higher carrier frequencies can present potential health risks. Insects closely associated with humans (such as mosquitoes) can undergo increased RF absorption and dielectric heating. This process inadvertently impacts the insects' behaviour, morphology, and physiology, which can influence their spread. Therefore, this study examined the impact of RF exposure on Ae. aegypti mosquitoes, which are prevalent in indoor environments with higher RF exposure risk. The morphologies of Ae. aegypti eggs and their developments into Ae. aegypti mosquitoes were investigated. A total of 30 eggs were exposed to RF radiation at three frequencies: baseline, 900 MHz, and 18 GHz. Each frequency was tested in triplicate. Several parameters were assessed through daily observations in an insectarium, including hatching responses, development times, larval numbers, and pupation periods until the emergence of adult insects. This study revealed that the hatching rate for the 900 MHz group was the highest (79 ± 10.54%) compared to other exposures (p = 0.87). The adult emergence rate for the 900 MHz group was also the lowest at 33 ± 2.77%. A significant difference between the groups was demonstrated in the statistical analysis (p = 0.03). This work highlighted the morphology sensitivity of Ae. aegypti eggs and their developments in the aquatic phase to RF radiation, potentially altering their life cycle.

Do magnesium and chloride ameliorate high sodium bicarbonate concentrations? A comparison between laboratory and mesocosm toxicity experiments

Increasing salinity is a concern for biodiversity in many freshwater ecosystems globally. Single species laboratory toxicity tests show major differences in freshwater organism survival depending on the specific ions that comprise salinity types and/or their ion ratios. Toxicity has been shown to be reduced by altering ionic composition, despite increasing (total) salinity. For insistence, single species tests show the toxicity of sodium bicarbonate (NaHCO3, which commonly is a large proportion of the salts from coalbeds) to freshwater invertebrates is reduced by adding magnesium (Mg2+) or chloride (Cl−). However, it is uncertain whether reductions in mortality observed in single-species laboratory tests predict effects within populations, communities and to ecosystem processes in more complex multi-species systems both natural and semi-natural. Here we report the results of an outdoor multi-species mesocosm experiment to determine if the effects of NaHCO3 are reduced by increasing the concentrations of Mg2+ or Cl− on: a) stream macroinvertebrate populations and communities; b) benthic chlorophyll-a and; c) the ecosystem process of leaf litter decomposition. We found a large effect of a high NaHCO3 concentration (≈4.45 mS/cm) with reduced abundances of multiple taxa, reduced emergence of adult insects and reduced species richness, altered community structure and increased leaf litter breakdown rates but no effect on benthic chlorophyll-a. However, despite predictions based on laboratory findings, we found no evidence that the addition of either Mg2+ or Cl− altered the effect of NaHCO3. In semi-natural environments such as mesocosms, and natural environments, organisms are subject to varying temperature and habitat factors, while also interacting with other species and trophic levels (e.g. predation, competition, facilitation), which are absent in single species laboratory tests. Thus, it should not be assumed single-species tests are good predictors of the effects of changing ionic compositions on stream biota in more natural environments.

Seed storage proteins and seed coat compounds additively influence Callosobruchus maculatus Fab. tolerance in selected cowpea (Vigna unguiculata L. Walp.) varieties

AbstractThe cowpea weevil, Callosobruchus maculatus, is a major threat to stable cowpea production, especially in storage, and has been reported to facilitate postharvest losses in cowpea grains. Host resistance has been suggested as the best control method but with conflicting knowledge on the source of resistance. Hence, the study seeks to evaluate seed storage proteins (SSPs) and seed coat compounds (SCCs) associated with tolerance to C. maculatus. SSPs and SCCs were assayed and associated with C. maculatus tolerance in 19 cowpea varieties with varied tolerance levels using a stepwise multiple regression analysis. Top C. maculatus tolerants were TVu‐2027, TVu‐11952, TVu‐11953, and TVu‐145. The protein fraction with a mass of 51 kDa was a significant predictor associated with percentage adult insect emergence (PAE) and host suitability index (H.S.I.), and 57 and 71 kDa were associated with mean development period (MDP) whereas 59 and 131 kDa were associated with seed damage tolerance (TolSD). Several SCCs identified were associated with the C. maculatus tolerant measures used in the study. However, Thiazole, tetrahydro‐ and Undecane were consistently identified with C. maculatus tolerance. Higher phenotypic variability was accounted for by SCC than SSP fractions associated with C. maculatus tolerance in the study indicating that SCCs contributed more to the C. maculatus tolerance than the SSPs identified. These compounds can be incorporated into breeding for C. maculatus tolerant in cowpea and biopesticide formulations whereas cowpea varieties with the high or significant amount of these compounds can also be recommended to the farmers or to the cowpea producers.

Selectivity of Bacillus thuringiensis (Bacillales: Bacillaceae) to the polyphagous predator Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae)

AbstractBioinsecticides based on Bacillus thuringiensis (Bt) are widely used to control agricultural pests. However, there are concerns about their impact on non‐target organisms, with for example, the green lacewing Ceraeochrysa claveri, a polyphagous predator with important value in the biological control of insect pests in agroecosystems. This study aimed to analyse the effects of Agree® bioinsecticide (containing Bt serovar aizawai GC‐91) on the post‐embryonic development of C. claveri. For this, neonate larvae of C. claveri were fed with Diatraea saccharalis eggs contaminated with different concentrations of Agree® (0.62, 1.25, 2.50 and 5.00 g L−1) until their pupation. Samples of the midgut of larvae were collected for histological and ultrastructural analysis. The larval and pupal inviability data were collected at the end of the respective developmental stages. After the emergence of adult insects, were considered inviable those with morphological alterations. To evaluate the reproduction, adult insect couples were formed, and the oviposition was collected. No significant differences in the viability of eggs, larvae, pupae and adults of C. claveri contaminated with Agree® were reported. Midgut analyses did not reveal cellular damage in the epithelium, indicating a possible lack of insecticidal proteins receptors. The oviposition and their viability were similar between treated and control groups. Our results demonstrated that Agree® bioinsecticide did not affect the post‐embryonic development of C. claveri. This illustrates that the combined use of Bt and C. claveri for the biological control of arthropod pests can be a sustainable strategy for integrated pest management.

Emergence phenology of the giant salmonfly and responses by birds in Idaho river networks

Emergence of adult aquatic insects from rivers is strongly influenced by water temperature, and emergence timing helps to determine the availability of this ephemeral food resource for birds and other terrestrial insectivores. It is poorly understood how spatial heterogeneity in riverine habitat mediates the timing of emergence. Such spatiotemporal variation may have consequences for terrestrial insectivores that rely on aquatic-derived prey resources. We investigated emergence phenology of the giant salmonfly, Pteronarcys californica, at three spatial scales in two Idaho river networks. We examined the influence of tributary confluences on salmonfly emergence timing and associated insectivorous bird responses. Salmonfly emergence timing was highly variable at the basin-scale during the period we sampled (May–June). Within sub-drainage pathways not punctuated by major tributaries, emergence followed a downstream-to-upstream pattern. At the scale of reaches, abrupt changes in thermal regimes created by 10 major tributary confluences created asynchrony in emergence of 1–6 days among the 20 reaches bracketing the confluences. We observed 10 bird species capturing emerged salmonflies, including 5 species typically associated with upland habitats (e.g., American robin, red-tailed hawk, American kestrel) but that likely aggregated along rivers to take advantage of emerging salmonflies. Some birds (e.g., Lewis’s woodpecker, western tanager, American dipper) captured large numbers of salmonflies, and some of these fed salmonflies to nestlings. Emergence asynchrony created by tributaries was associated with shifts in bird abundance and richness which both nearly doubled, on average, during salmonfly emergence. Thermal heterogeneity in river networks created asynchrony in aquatic insect phenology which prolonged the availability of this pulsed prey resource for insectivorous birds during key breeding times. Such interactions between spatial and temporal heterogeneity and organism phenology may be critical to understanding the consequences of fluxes of resources that link water and land. Shifts in phenology or curtailment of life history diversity in organisms like salmonflies may have implications for these organisms, but could also contribute to mismatches or constrain availability of pulsed resources to dependent consumers. These could be unforeseen consequences, for both aquatic and terrestrial organisms, of human-driven alteration and homogenization of riverscapes.

Ocorrência de Dinarmus basalis parasitando Callosobruchus maculatus em Vigna unguiculata no semiárido do Rio Grande do Norte, Brasil

ABSTRACT Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae: Bruchinae) is the main pest of Vigna unguiculata (L.) Walp. during the grain storage period. This study aimed to report the occurrence of a natural enemy associated with C. maculatus in cowpea, in the semiarid region of the Rio Grande do Norte state, Brazil. For this, cowpea samples were collected and placed in closed plastic containers, where they remained until the emergence of adult insects. From the infested samples, adults of C. maculatus and of the Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae: Pteromalinae) parasitoid emerged. This is the first report of D. basalis parasitizing C. maculatus in the semiarid region of the Rio Grande do Norte state.

Occurrence of Eubulus sp. (Coleoptera: Curculionidae) in fruits of Alibertia edulis (Rich.) A. Rich. (Rubiaceae) in the Cerrado of Minas Gerais, Brazil

The puruí Alibertia edulis (Rich.) A. Rich. (Rubiaceae) is a naturally occurring species in the Cerrado biome in Brazil; its fruits serve as food for the local fauna (birds and mammals) and humans. Here, we report on a beetle feeding on the fruits of A. edulis in the Cerrado of Minas Gerais (MG). Monthly collections were carried out in four A. edulis trees in two areas of Cerradão in the vicinity of the municipality of Monte Carmelo, MG, between September and October 2018. These were a legal reserve area of Fazenda Juliana (ARL; Juliana Farm; 18°42'30 "S and 47°33'05 "W) and an area at the Atalho Community (ACA; 18°41'39 "S and 47°34'49 "W). Fruits with or without attack symptoms were collected from the treetop in the four cardinal directions. A total of 100 fruits (50 from each area) were collected from the trees and packed into plastic bags. The fruits were then transported to the laboratory, stored in plastic containers isolated with voile fabric, and checked daily for the emergence of adult insects. After emergence, the insects were identified. During the evaluation period, 33 beetles emerged in puruí fruits from ARL and 13 from ACA. The species has been identified as Eubulus (Kirsch) sp. (Coleoptera: Curculionidae). The animals consumed the entire fruit endocarp, leaving it with emergence orifices caused by the adult emergence. It is concluded that Eubulus sp. feeds on the pulp of A. edulis and is able to compete for this resource with other animal species.

Peniocereus serpentinus AND Austrocylindropuntia subulata, NEW HOSTS OF THE CACTUS WEEVIL (Metamasius spinolae Gyllenhal) IN THE STATE OF MEXICO

The cactus weevil (Metamasius spinolae) is a pest of Opuntia ficus-indica. It can develop not only in Opuntia species but also in other cacti and members of the Asparagaceae family. In 2017, damage and presence of adult insects with characteristics similar to the cactus weevil were reported in two species of cacti, Austrocylindropuntia subulata and Peniocereus serpentinus. The objective was to identify the insect and determine if the two cacti species are hosts, field and laboratory research was conducted from 2017 to 2019 in the municipality of Axapusco, State of Mexico. Stems with larval damage were selected at four study sites, whic remained in field conditions until the emergence of adult insects. The behaviour of M. spinolae on the host plant, mating sites, incubation period and damage development over time were recorded. M. spinolae was identified and determined to fulfill its life cycle on A. subulata and P. serpentinus. Larvae cause the most damage by feeding on the internal part (pith) of the stems, which causes tissue rotting and death of the affected part. The adult feeds on tender buds and mature stems, causing deformation and weakening of the plant. The two cacti species proved to be host plants that can harbour populations of M. spinolae and, therefore, have a high potential to act as reservoirs of the pest, which can then migrate to prickly-pear cactus crop. This report expands the knowledge of hosts of the cactus weevil. The information obtained shall be useful for vegetable growers to apply phytosanitary measures in alternate hosts, combat reservoirs and avoid re-infestations of the pest.

An attractor domain model of seasonal and inter‐annual β diversity of stream macroinvertebrate communities

Abstract Ecological communities are dynamic systems that vary within and across years. In streams, disturbance by spates and the emergence of adult insects during the rainy summer contrast with more stable conditions in the dry winter and can potentially generate distinct and repeatable community states across years. However, demographic stochasticity and the legacies of previous spates may hamper the full attainment of characteristic community states associated with seasons. We developed an attractor domain model encapsulating these factors and hypothesised: (1) partially distinct rainy (summer) and dry (winter) communities. High benthic dynamism during the rainy period should cause higher inter‐annual variability, leading to (2) higher temporal β diversity among rainy periods than among dry periods. Historical effects (e.g., demographic stochasticity and disturbance by spates) should accumulate over the years and lead to (3) increased variation in community structures sampled further apart in time; furthermore, (4) this increase in variation should be higher among rainy than among dry communities. We used data of stream macroinvertebrates (mostly insects) in a subtropical basin in Brazil to evaluate inter‐annual variation using rank‐concordance statistics of the most common species and dissimilarity using all species. For each stream site, samples obtained in the two seasons tended to show distinct community structure using relative abundance data but were much less distinct using species composition (presence–absence). Temporal β diversity was higher among rainy than among dry seasons. The β diversity of both seasons increased with time, although this increase was 2–3 times greater during the rainy season. Our results support a model in which rainy (summer) communities are disrupted by the high dynamism caused by spates and the emergence of adult insects. The low intensity of these two factors during dry (winter) periods allows local environmental conditions to drive community structures toward a less variable, recurrent attractor state. However, the increase in β diversity with time indicates that the legacy effects of previous disturbances and demographic stochasticity preclude the full attainment of a definite stable state and that only a domain of states is approached.

OVIPOSITION OF THE GALL WASP LEPTOCYBE INVASA (HYMENOPTERA: EULOPHIDAE) AND MORPHOLOGICAL CHANGES IN EUCALYPTUS SPP. GENOTYPES SUSCEPTIBLE

Eucalyptus is grown worldwide for many purposes, as for production of wood, firewood, cellulose and essential oils. Eucalyptus was introduced into Brazil in 1904, and its cultivation has been growing since that time, with about 5.57 million hectares of plantations in 2014. This increase in plantations has favored the native insect populations, some insects have become pests, while other exotic insect pests were introduced such as the gall wasp ( Leptocybe invasa ), which oviposits in the midrib of leaves, petiole, and in young shoots, causing the formation of galls which compromise the normal growth of plants. In order to evaluate the morphological changes in genotypes of Eucalyptus spp., caused by the galls formation, the anatomical alterations qualitative and quantitatively of the vascular bundles were studied. The results showed that oviposition occurs in the four genotypes studied, but the genotype 1404 is resistant to gall formation, while the susceptibility is low in genotype 1277, medium in genotype 1724 and very high in genotype 1262. The vascular bundles and parenchyma cells in the leaves and petioles were disorganized. The emergence of adult insects caused ruptures in vascular, parenchyma and epidermal cells, resulting in necrosis and foliar droughtness.

Effect of Insect Growth Regulators “Dimilin25% wp and Match 50 EC” Against House Fly (Musca domestica) Life Stages (Diptera: Muscidae)

The study was conducted to identify the effect of growth regulators “Match and Dimilin” using different concentrations on the incomplete life stages of the house fly, and calculating the percentages of egg hatching, incapability of larvae pupation and emergence of adult insects in laboratory conditions. All the concentrations showed different percentages in their effect on the life stages of the insect, whereas the effects were increased with the exposure rate increasing. However, the hatching rate for eggs in the concentration of (1000) mg/l reached to (0.00%) for the Match growth regulator, while it reached (20.50%) for the Dimilin regulator at the same concentration. In the larval stages, the percentage of larvae that reached the pupa phase in concentration of (1000) mg/l for both growth regulators was (0.00%), while the emergence rate of adults for the same concentration was reached in growth regulators Match and Dimilin for (25.33%) and (10.33%) respectively

Peptide fraction from latex of Calotropis procera exhibits antifungal and insecticidal activities

Latex is an endogenous fluid exuded by some plants after injury. It is rich in different molecules and has shown many biological activities against different fungi and insects. This work aimed to isolate a peptide fraction from Calotropis procera (PepCp) latex and to evaluate its activity against two fungi and an insect. The chromatographic profile showed that PepCp is constituted mainly by 7 kDa peptides. PepCp showed a low effect against the spore germination of both fungi Colletotrichum gloeosporioides and Fusarium solani. However, PepCp (1.25 mg mL−1) inhibited the mycelial growth of C. gloeosporioides by 80%. On the other hand, PepCp, 0.05% (w/w), reduced the larval weight of Callosobruchus maculatus by 90%, and at 0.2%, no larva was found. At 0.05%, there was a delay of 2 days in the emergence of adult insects, while at 0.1%, no emergence of adult insects was noticed. Our results corroborate the hypothesis of the defense role played by latex and that PepCp can be an interesting biological source of new fungicidal or insecticidal peptides.

Essential oils for the control of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) and effect on the quality of the corn grain Zea mays Linnaeus (Poales: Poaceae)

In order to find natural alternatives for the control of the weevil Sitophilus zeamais Motschulsky, the effect of niaouli (Melaleuca quinquenervia), eucalyptus (Eucalyptus globulus) and oregano (Origanum vulgare) essential oils were studied on mortality, emergence and epellency of S. zeamais, as well as their effect on the grain quality of corn during storage (germination, amount of phenols, flavonoids and antioxidant capacity). The technique used for the bioassays was saturation of atmospheres, in volumes of 100, 200 and 300 µL, having national white corn as substrate. The three oils showed 100% insecticidal activity at 72 hrs. The emergence of adult insects (F) was null in all treatments. Repellency was observed in all treatments at 24, 48 and 72 hrs. Germination was not affected in volumes of 100 µL. The content of total phenols and flavonoids were higher both in the oregano oil (94.68 mg GAE/g and 0.27 mg QE/g respectively) and in the corn treatment with oregano (16.09 mg GAE/g and 0.18 mg QE/g respectively). Similar behavior was observed in the antioxidant capacity in both DPPH and ABTS, presenting ranges from 76.31 to 93.73% inhibition. It is concluded that the three essential oils have potential for the control of S. zeamais, improving the quality of the corn grain.

DNA <i>barcoding</i> de <i> Oncideres saga</i> (Coleoptera: Cerambycidae) do Brasil

Utilizar ferramentas moleculares aliadas a técnicas tradicionais de identificação para determinar corretamente as espécies, a diversidade genética e o fluxo gênico de insetos-praga florestais é um dos maiores avanços dos últimos anos. Nesse sentido, o objetivo do trabalho foi realizar o DNA barcoding da espécie Oncideres saga (Dalman, 1823), utilizando o primeiro fragmento do gene mitocondrial Citocromo Oxidase I (COI). Em Seropédica, Rio de Janeiro, galhos de Albizia lebbeck (L.) Benth., anelados por uma espécie de Cerambycidae, foram coletados e armazenados em laboratório sob condições controladas até a emergência dos insetos adultos. Um total de 13 insetos emergiram e, a partir das características morfológicas, foram identificados como Oncideres saga. Oito espécimes adultos foram utilizados para a caracterização molecular a partir do gene mitocondrial Citocromo Oxidase I (COI). Após a obtenção do DNA genômico e amplificação do gene COI via PCR, os produtos foram sequenciados gerando um fragmento com 639 pb. Este é o primeiro estudo molecular que caracteriza o DNA barcoding de Oncideres saga, que é uma espécie geneticamente distinta das demais do gênero Oncideres. Esta pesquisa traz informações básicas que poderão ser utilizadas para explorar novas populações desse inseto-praga em futuros estudos moleculares e aplicados.

Assessing Megastigmus specularis (Hymenoptera: Megastigmidae) infestations in a Fraser fir (Abies fraseri (Pursh) Poir.) clonal seed orchard of the southern Appalachians

ABSTRACT The Christmas tree industry is mainly supplied with seeds from natural stands and genetically improved germplasm from clonal seed orchards (CSOs). Chalcid wasps (Megastigmus spp.) have a negative effect on the value of seedlots by reducing the quantity of viable seeds and represent a risk for national and international seed trade. Seed radiographies, field observations and seed-dissections from 25 Fraser fir (Abies fraseri (Pursh) Poir.) clones were used to determine chalcid infestation in a CSO of the southern Appalachians. We provided direct evidence that Mesopolobus cf. pinus is an ectoparasitoid of M. specularis, proposed a model that linked different aspects of the biology of these species and discussed host–insect phenological relationships. Infestation of seeds in some clones across surveys, suggested a potential genetic component to chalcid wasp's prevalence. Cold and dark rearing regimens were used to identify changes in adult insect emergence after variation of overwinter conditions. Both the frequency and the time of emerging M. specularis adults from seeds were affected by the duration of the treatments but not statistical differences were found for Mesopolobus cf. pinus. We present evidence for the efficiency of a gravity-seed cleaning method eliminating upwards of 95% of chalcid-infested seeds.

Identification and Abundance of Fruit Fly Species Responsible for Fruit Drop of Sweet Orange (Citrus sinensis L. Osbeck) in Benue State, Nigeria

Background and Objective: Citrus is one of the most important and among the top ten widely cultivated fruits in Nigeria. It is produced more in the Guinea and Sudan Savanna zones of the country with Benue State having the highest annual production. In the South of Savanna region of Africa, particularly in Nigeria; despite the economic, nutritional and health benefits of citrus, limited research work has been carried out on the identification and control of fruit flies of economic importance to the crop. The objectives of this study are to identify and determine the abundance of the fruit fly species responsible for fruit drop of citrus in Benue State, Nigeria.
 Materials and Methods: Fruit fly identification was done through fruit culture experiment carried out in the College of Agronomy Teaching and Research Farm, Federal University of Agriculture, Makurdi in October 2014 and October 2015.The experiment was a 2 x 3 factorial in a completely randomized design with four replications. The two factors were Zones (Zone A and B) and Varieties (Ibadan Sweet, Valencia and Washington Navel). Ten naturally infested orange fruits from four randomly selected citrus trees of each variety in each zone were weighed and placed in each plastic rearing box with dimension 39 x 27 x 26 cm containing sterilized moist soil securely covered with 1 mm mesh net for pupation and adult insect emergence. Emerged adults were killed using Mobil insecticide (Cyphenothrin), counted, sexed and stored in specimen bottles with 70% alcohol for preservation and later identification.
 Results: Fruit fly species identified from citrus fruit culture were: Bactrocera invadens (Drew), Ceratitis capitata (Weid) and Dacus bivittata (Biggot). Bactrocera invadens were the most abundant species and accounted for 63.70% in Washington navel and 63.10% in Valencia in 2014 and 2015 respectively. The varieties showed no significant differences (p>0.05) on the abundance of Ceratitis capitata and Dacus bivittata in 2014. In 2015 however, Ibadan Sweet variety showed significant difference (p < 0.05) on the abundance of Ceratitis capitata (28.30%) when compared with other varieties (15.8%) each.
 Conclusion: Fruit fly species responsible for citrus fruit drop in Benue State were Bactrocera invadens (Drew), Ceratitis capitata (Weid) and Dacus bivittata (Biggot) with Bactrocera invadens (Drew) recorded as the most abundant species.

Fumigant toxicity of Lavandula spica essential oil and linalool on different life stages of Tribolium confusum (Coleoptera: Tenebrionidae)

Abstract The confused flour beetle, Tribolium confusum, is a common and severe pest of stored products. Here, using fumigation tests during four different exposure times, we evaluated the toxicity of different doses of essential oil of spike lavender, Lavandula spica and one of its major constituents, linalool, on different life stages of T. confusum under laboratory conditions. The toxicity of the L. spica oil and linalool varied as a function of the developmental stage and treatment duration. Young larvae (L1) were the most susceptible to toxic effects, with LC50 = 19.535 μl/L of air for L. spica oil and LC50 = 14.198 μl/L of air for linalool after 24 h of exposure, whereas older larvae (L8) were affected only very little by fumigation. Linalool caused higher egg mortality than L. spica oil at equivalent doses, but lower mortality in pupae and adults. Emergence of intact adult insects from surviving eggs, larvae and pupae was further reduced as a function of dose and exposure time to both L. spica oil and linalool compared to control-treated insects. Our results show that L. spica oil and linalool might be suitable for biological control of T. confusum, but tests at a larger scale are necessary to confirm our results.

Association of low concentrations of pyriproxyfen and spinosad as an environment-friendly strategy to rationalize Aedes aegypti control programs

The association of low concentrations of pyriproxyfen and Spinosad, a naturally-occurring insecticide, was evaluated as an environment-friendly strategy to rationalize Aedes aegypti control programs by reducing larvicide consumption, saving financial costs and increasing residual effect against mosquitoes development. Firstly, the ecotoxicological parameters of the mixture was performed on non-target species Daphnia magna and the results confirmed that the low concentrations used in this larvicide mixture were not able to alter the reproductive parameters of chronically exposed microcrustaceans. In contrast, the mixture altered the behavior and development of Aedes aegypti, effectively inhibiting the emergence of adult insects for a long period. The results confirm the hypothesis that even at very low concentrations, the combination of the Spinosad and Pyriproxyfen larvicides offers an opportunity for Aedes aegypti public control programs to be more efficient.

WITHDRAWN

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