Conotrachelus Psidii Research Articles

Sequential sampling plan for the adults of Conotrachelus psidii (Marshall, 1922) (Coleoptera: Curculionidae) in guava crop

AbstractUnderstanding the spatial distribution and population fluctuations of insect pests facilitates the development of effective control strategies for a given crop. Conotrachelus psidii (Coleoptera: Curculionidae) is an important guava pest; however, no sampling plans are available for its management. Therefore, in this study, we aimed to (i) determine the spatial distribution pattern of C. psidii adults and (ii) develop a sequential sampling plan for pest control in guava crops. Evaluations began at 120 days after pruning and were performed weekly. To sample C. psidii adults, a white tarp was placed under the plants, covering the entire canopy. Plant branches were then shaken to dislodge the adult insects on the tarp, which were then identified and counted. Using the data obtained in each sampling, dispersion indices were determined and tests of adjustments to the theoretical Poisson and negative binomial frequency distributions were performed. The calculated dispersion indices revealed that the individuals in the studied populations exhibited aggregated dispersion. Notably, only four samples showed adjustment to the Poisson distribution, whereas 18 samples showed adjustment to the negative binomial distribution in the field, confirming the aggregated pattern of the population spatial arrangement. The sequential sampling plan developed for C. psidii revealed the maximum and minimum numbers of sample units expected for decision‐making as 45 and 15, respectively.

Bioecology of the guava weevil Conotrachelus psidii Marshall (Coleoptera: Curculionidae)

The guava weevil, Conotrachelus psidii Marshall (Coleoptera: Curculionidae), is a key pest in guava and information concerning the bioecology of this insect is scarce. This work aimed to verify the bioecology of certain aspects of this insect's lifecycle by observations of the period during which the larvae abandon the fruits in order to enter the soil to pupate, the effect of different soil types on penetration times and the subsequent emergence of adults from the soil. Adult population levels were monitored over a two year period and the possible relationship between population density and climatic factors investigated. The abandonment of guava fruits by the larvae was evaluated during two time periods (day-time and night-time). The time taken for 4th instar larvae to penetrate 3 different soil types was observed. The time these insects remained underground and subsequent adult emergence periodicity was evaluated following the release of 4th instar larvae into trays filled with soil. These trays were maintained in the field and observations carried out three times a day (morning, noon, and afternoon). Path analysis was used to investigate the relationship between the climate variables and adult population density. Soil penetration by 4th instar larvae was fastest in clay soils and slowest in sand. There was no difference (p = 0.075) between the number of larvae that abandoned the fruits during the day (51%) and during the night (49%). A majority of the adults emerged from the soil during daytime (86.84%), which was significantly different (p < 0.001) to the number of adults emerging during the night (13.16%). When comparing adult emergence during different periods of the day, the majority emerged in the afternoon (93.94%), with only 6% emerging in the morning (p < 0.001). The average time period between penetration of the soil by 4th instar larvae and adult emergence was approximately nine months (272 days). Adult population density fluctuations were similar during both years studied here, with the lowest population seen from May to August, a peak in November, and then a decline in population density until March. Path analysis showed that rainfall positively influenced C. psidii population density. The results of this work will be important for the development of sustainable IPM programs aiming to control this serious pest of guava orchards.

Mapping the Spatial Distribution of Conotrachelus psidii (Coleoptera: Curculionidae): Factors Associated with the Aggregation of Damage.

The guava weevil, Conotrachelus psidii Marshall, is one of the key pest species of Psidium guajava L. fruit in Colombia. Adults that emerge after completing development on the ground attack the guava fruits in some areas of the crop more than in others. During development, the weevil spends 3-6months in the soil, suggesting that edaphoclimatic factors may influence its biology, and hence, the spatial distribution and damage pattern caused by weevils within the guava orchard. Understanding this pattern allows specific control practices to be used at crop sites. The trials were performed in a commercial orchard of 3.5ha. Samples of damaged fruits were taken from each tree, and edaphoclimatic variables such as soil moisture, mechanical resistance, apparent density, texture, precipitation, solar radiation, temperature, and relative humidity were recorded. The data were analyzed using the basic stages of a geostatistical analysis. The findings indicate that the highest numbers of damaged fruits were correlated with areas within the surveyed field where the soil moisture ranged between 27 and 34% in rainy seasons and where the clay content was less than 30% and the silt content was 42% of the surveyed field. A linear model of the infestation was obtained, associated with the climatic variables that determine the environmental conditions and can favor the development of the weevil populations. With the information obtained, localized and efficient management of the guava weevil can be established.

Occurrence of Conotrachelus psidii (Marshall, 1922) in Psidium cattleianum (Sabine)

The guava weevil, Conotrachelus psidii (Marshall, 1922) (Coleoptera: Curculionidae), has been reported to be harmful to guava fruit, causing deterioration. However, the occurrence of this insect and resulting damage in araçazeiro Psidium cattleianum (Sabine) fruit has not yet been described. For this reason, the objective of this study was to report the occurrence of C. psidii in araçá (P. cattleianum). In May 2015, the occurrence of C. psidii in araçá trees of the P. cattleianum species was investigated. Recordings were performed in the experimental area of UNEPE Viveiro de Plantas Hortícolas (geographical coordinates 25º41'37”S and 53º06'07”W, average altitude of 502m) at the Federal University of Technology (UTFPR-DV), Dois Vizinhos – PR.

Mortality of Conotrachelus humeropictus in response to combined application of the nematode Steinernema brazilense and the fungus Beauveria bassiana

ABSTRACT: The fruit borer Conotrachelus humeropictus is one of the most important pests of the cupuaçu crop, and can promote yield losses of around 50%. The present study involved the selection of Beauveria bassiana isolates on Conotrachelus psidii larvae, which was used as test insect due to its taxonomic closeness to C. humeropictus. In order to assess their interaction using combined application, we studied the ability of the nematode to carry conidia of B. bassiana and Metarhizium anisopliae to soil layers. This study also aimed to establish a biological control method for cupuaçu borer with the use of the fungus B. bassiana at 10 kg/ha and the entomopathogenic nematode Steinernema brazilense at 1, 3, 9, and 27 IJ/cm2, applied as single and combined treatments. In the selection of B. bassiana strains for C. psidii, the IBCB 276 and IBCB 165 isolates were the most promising ones, causing 86 and 84% mortality, respectively. The IBCB 276 strain was applied in the field to control C. humeropictus. In the study of carriage of conidia in soil, the nematode S. brazilense was found to be capable of carrying conidia of B. bassiana to deep 7 to 10 cm soil layers. This was not observed with M. anisopliae, found only in the topsoil. In field trials against C. humeropictus larvae, B. bassiana promoted 15.6% mortality. The nematode promoted 60.0% mortality at the highest concentration used, and their combined use with B. bassiana (10 kg/ha) increased mortality to 65.6%, with an additive interaction observed between the two entomopathogens.

Acca sellowiana(Myrtaceae): A New Alternative Host forDrosophila suzukii(Diptera: Drosophilidae) in Brazil

Summary We report, for the first time, the occurrence and development of Drosophila suzukii Matsumura (Diptera: Drosophilidae) in fruits of Acca sellowiana (Berg) Burret (Myrtaceae). Although fruits of A. sellowiana present hard and thick skin, damage caused by another insect pest, Conotrachelus psidii Marshall (Coleoptera: Curculionidae), may have enabled fruit infestation by D. suzukii.

(1R,2S,6R)-Papayanal: a new male-specific volatile compound released by the guava weevil Conotrachelus psidii (Coleoptera: Curculionidae).

The guava weevil, Conotrachelus psidii is an aggressive pest of guava (Psidium guajava L.) that causes irreparable damages inside the fruit. The volatile compounds of male and female insects were separately collected by headspace solid-phase microextraction or with dynamic headspace collection on a polymer sorbent, and comparatively analyzed by GC-MS. (1R,2S,6R)-2-Hydroxymethyl-2,6-dimethyl-3-oxabicyclo[4.2.0]octane (papayanol), and (1R,2S,6R)-2,6-dimethyl-3-oxabicyclo[4.2.0]octane-2-carbaldehyde (papayanal) were identified (ratio of 9:1, respectively) as male-specific guava weevil volatiles. Papayanal structure was confirmed by comparison of spectroscopic (EIMS) and chromatographic (retention time) data with those of the synthetic pure compound. The behavioral response of the above-mentioned compounds was studied in a Y-tube olfactometer bioassay, and their role as aggregation pheromone candidate components was suggested in this species.

Chemical Signaling Between Guava (Psidium guajava L., Myrtaceae) and the Guava Weevil (Conotrachelus psidii Marshall)

&lt;div class="WordSection1"&gt;&lt;p class="Default"&gt; Volatile organic compounds (VOCs) from guava (&lt;em&gt;Psidium guajava &lt;/em&gt;L.) reproductive tissues (flower bud, open flower, petal fall, fruit setting, and fruit growth) were collected &lt;em&gt;in situ &lt;/em&gt;during the day by headspace-solid phase microextraction (HS-SPME), and from flower bud and fruit setting by dynamic headspace (DHS). The samples were analyzed by GC-MS to separate and identify VOCs produced by guava, which potentially could attract the guava weevil &lt;em&gt;(Conotrachelus psidii &lt;/em&gt;Marshall, Coleoptera: Curculionidae), one of the most important pests of guava plants in Colombia and Brazil. The terpenes &lt;em&gt;β&lt;/em&gt;-caryophyllene, limonene, and copaene (tentatively identified) were present in all of the guava reproductive tissues, being the major constituents in flower bud and fruit setting, the two guava stages where &lt;em&gt;C. psidii &lt;/em&gt;is commonly found. Additionally, the volatile compounds released by male and female insects were separately collected by HS-SPME, and comparatively analyzed by GC-MS. As result, some of volatile detected in the guava reproductive tissues were also released from insects. The behavioral response of the volatile blends and the above-mentioned compounds was studied in a Y-tube olfactometer bioassay, allowing confirming the presence of host kairomones in the guava reproductive tissues.&lt;/p&gt;&lt;/div&gt;

(1R,2S,6R)-Papayanol, Aggregation Pheromone of the Guava Weevil,Conotrachelus psidii

Comparative GC/MS analysis of airborne volatiles produced by males and females of the guava weevil Conotrachelus psidii (Coleoptera: Curculionidae: Molytinae) showed the presence of a malespecific electroantennographically active compound identified as (1R,2S,6R)-2-hydroxymethyl-2,6- dimethyl-3-oxabicyclo[4.2.0]octane (papayanol). Release of this compound was dependent on the photoperiod, taking place primarily during the scotophase, with a maximum release between 2 and 6 h after the onset of the scotophase. Y-tube olfactometer bioassays revealed a strong attractiveness of the papayanol to male and female weevils considering the presence of the plant volatiles.

Aspectos biológicos e técnica de criação do gorgulho-da-goiaba, Conotrachelus psidii marshall (Coleoptera: Curculionidae)

Considerada praga-chave da cultura da goiaba, Conotrachelus psidii Marshall (Coleoptera: Curculionidae) tem causado grandes prejuízos em vários países produtores desta fruta. A pesquisa objetivou avaliar os parâmetros biológicos da praga, sob condições controladas, através do desenvolvimento de uma técnica de criação que permitiu efetuar observações diárias de pré-pupas e pupas. Constatou-se que o substrato adequado para manutenção dessas fases foi o solo argiloso umedecido com viabilidade de 78%, sendo este o tipo de solo utilizado na técnica de criação, que foi desenvolvida para trabalhos em câmara climatizada, à temperatura constante de 25 ± 1º C, fotoperíodo de 12 horas e UR de 70% ± 10%. Quanto aos aspectos biológicos, a duração média do período de ovo, larva, pré-pupa, pupa e ovo-pupa foi de: 4,25; 12,2; 106,6; 14,88 e 138,4 dias, respectivamente. A duração média do período da fase adulta, no solo, início da alimentação, pré-oviposição, longevidade e pós-oviposição foi de, 22; 11; 51,9; 149,32 e 7,18 dias, respectivamente. O período médio de oviposição foi de 120,27 dias, com um número médio de 343,63 ovos por fêmea. A técnica de criação desenvolvida permitiu acompanhar diariamente o desenvolvimento de pré-pupas, pupas e adultos do gorgulho-da-goiaba, sem que eles necessitassem reconstruir nova câmara, mostrando ser menos estressante e onerosa do ponto de vista energético.

&lt;b&gt;Biological characterization of the colombian isolate&lt;i&gt; Heterorhabditis&lt;/i&gt; sp. SL0708 (Rhabditida: Heterorhabditidae&lt;/b&gt; - doi: 10.4025/actascibiolsci.v35i3.16034

Heterorhabditis sp SL0708 (Rhabditida: Heterorhabditidae) is a native entomopathogenic nematode from Alcala, Valle del Cauca (Colombia), a natural enemy of insects that can be used for controlling Plutella xylostella L, Conotrachelus psidii Marshall and Delia platura (Meigen); however its biological characterization is unknown. In order to know about the infective capacity of the isolate, tests were made with last instar larvae of Galleria mellonella (Lepidoptera: Pyrallidae) on penetration, one by one, exposure time, dose response and foraging strategy. The average infecting juveniles (IJ) entering larvae was 3 (1.5%). In the one-on-one test, larvae mortality ranged between 8.3 and 16.7%. There was no significant difference (p < 0.05) between treatments and in number of dead larvae in the exposure time and dose response assays. Heterorhabditis sp. SL0708 presented a cruiser foraging strategy, which indicates that it can be used for sessile or cryptic hosts.

Olfactory responses of Conotrachelus psidii (Coleoptera: Curculionidae) to hosts and conspecific odors

Conotrachelus psidii (Coleoptera: Curculionidae) is one of the most important pests of guava plants, Psidium guajava (Myrtaceae). Guava plant is the natural host of this weevil suggesting that volatile compounds from odor of different parts of the plant may be attractive to this insect. The main goal of this research was to determine if host or conspecific odors can act as attractants to guava weevil. The olfactory responses of the guava weevil were tested with a Y-tube olfactometer. The odors included green and ripened fruits, leaves and flower buds of P. guajava, guava weevils and their feces. Stimuli were tested singly and in combinations. Flower buds odors were attractive to C. psidii males suggesting the presence of host kairomones. Males and females weevil feces attracted both male and female weevils, indicating the existence of aggregation pheromones or allelochemicals (undigested plant compounds) in the feces. Further studies should be made to conclude from the nature of these substances. Identification and synthesis of the semiochemicals that attract the guava weevil would allow developing new strategies for monitoring and controlling this pest.

Efficacy of some biodegradable films as pre-harvest covering material for guava

To produce guavas with good commercial or industrial potential, fruit farmers use phytosanitary practices such as fruit bagging. Bagging protects the fruit mainly from the attack of pests, such as the fruit fly ( Anastrepha spp.) and the guava weevil ( Conotrachelus psidii), and reduces the use of insecticides and fungicides. This investigation aimed to develop and produce biodegradable films from cassava starch and poly(butylene adipate-co-terephthalate) (PBAT) by extrusion for application in pre-harvest guava fruit bagging. After the fruit harvest, for 6–9 weeks all films were more fragile and rigid, but did not present cracks. BF70 was the most fragile and had the greatest tendency to tear; however, it remained whole until harvesting. Fruit bagged with films BF30, BF50, BF70 was analyzed for fruit quality and compared with PSF control and non-bagged fruit. There was no difference between the treatments relative to physical and chemical characteristics, indicating that biodegradable film did not influence fruit development when compared to the PSF control.

Combining vegetable oil and sub-lethal concentrations of Imidacloprid with Beauveria bassiana and Metarhizium anisopliae against adult guava weevil Conotrachelus psidii (Coleoptera: Curculionidae)

Of the insect pests that attack guava fruits, the guava weevil, Conotrachelus psidii Marshall, 1922 (Coleoptera: Curculionidae), is one of the most important in Brazil. In search of alternatives to chemical pesticides, this study was performed to select fungal isolates of Beauveria bassiana and Metarhizium anisopliae as potential candidates for the control of adult C. psidii. Tests were carried out using three products applied with the entomopathogenic fungi: Tween 80, sunflower oil and Imidacloprid (IMI). A sub-lethal concentration of IMI was determined (100 ppm). The results demonstrated that LPP 19 and LPP 114 were the most effective isolates when used in combination with all of the products. The least virulent isolate, ESALQ 818, when applied in Tween 80 caused only 26.6% mortality, however, this isolate showed significantly improved efficiency when applied together with either sunflower oil or IMI, causing 57.3 and 88.6% mortality, respectively. The efficiency of all the isolates tested here improved when applied together with IMI, with LT50 values of 5.3–10.3 days when compared to LT50 values in Tween alone of 9.5–17 days. The isolate that produced the highest number of conidia on the cadavers of adult C. psidii was LPP138, independent of the product used; however, conidial production was slightly reduced when fungi were applied together with IMI. These results are promising for developing new formulations of the isolates to be tested in the field.

Efficacy of Heterorhabditis baujardi LPP7 (Nematoda: Rhabditida) applied in Galleria mellonella (Lepidoptera: Pyralidae) insect cadavers to Conotrachelus psidii, (Coleoptera: Curculionidae) larvae

The guava weevil, Conotrachelus psidii, is a major pest of guava in Brazil causing severe reduction in fruit quality. We assessed its susceptibility to Heterhorhabditis baujardi LPP7 infective juveniles (IJs) in the greenhouse and under field conditions applying the nematodes in cadavers of seventh instar Galleria mellonella larvae. Field persistence of these nematodes in the soil was evaluated through G. mellonella-baiting. Insect cadaver concentrations of 2, 4 and 6 applied in pots in the greenhouse experiment caused significant mortality compared to the control. Significance differences were observed in the field between control and treatments only when six cadavers per 0.25 m2 were applied. Infective juveniles from the cadavers persisted 6 weeks after application in the field, but decreased greatly thereafter. Our work demonstrates that H. baujardi LPP7 IJs emerging from G. mellonella cadavers can be efficacious against guava weevil fourth instar larvae. Also, we demonstrated the long-term persistence of IJs in the soil.

Dimorfismo sexual do gorgulho-da-goiaba Conotrachelus psidii Marshall (Coleoptera: Curculionidae)

We investigate structural and behavioral differences between male and female adults of guava weevil, Conotrachelus psidii Marshall, 1922 to help in sex determination. Weevils collected from a commercial guava orchard were individually caged and maintained under laboratory conditions. Every day ten individuals were grouped and their behavior was observed. During mating the males and females were identified. Fifty weevils of each sex were killed and they were observed with stereoscopic microscope. The antenna insertion on the rostrum and hair on the thorax and abdomen surfaces were examined. Length and width of body, pronotum, last abdominal sternite and rostrum were also taken. Behaviorally, the male weevils produce audible sound by stridulation of abdomen while females do not. In the females, the body and pronotum width and body a rostrum length were higher than in the males, but the last abdominal sternite was smaller. Three other structural differences were visible with the naked eye: 1) the anterior region of pronotum have scarce hair or have not in the females and hair is dense in the males; 2) the last tergite of females is hidden by the penultimate tergite whereas in the males is visible; 3) the first abdominal sternite of females is more prominent, very convex and without or with little bristle. In the males it is slightly concave and with abundant hair. The male-female differences found in this work allow, without hurt or change insect behavior, an efficient sex determination of guava weevil.

Biología del Picudo de la guayaba Conotrachelus psidii (Marshall) (Coleoptera: Curculionidae)

El Picudo, Conotrachelus psidii Marshall, desarrolla su estado larvario en el fruto de la guayaba alimentándose de la semilla; el insecto petrifica y madura prematuramente la fruta confiriéndole un aspecto desagradable que causa rechazo en el mercado. En la actualidad causa pérdidas significativas en la agroindustria de la Hoya de Río Suárez. Conocer la duración de los estadios biológicos y sus preferencias de oviposición, permitirá diseñar estrategias de manejo integrado. Los huevos y las larvas se obtuvieron semanalmente de frutos infestados artificialmente para conocer los cambios morfológicos de la cabeza de la larva y la duración del estadio. Cuando las larvas abandonaron el fruto se introdujeron en dispositivos plásticos tubulares saturados con tierra, los cuales se disectaron mensualmente para registrar los estadios de larva, pupa y adulto en el suelo. Se observó que las hembras ovipositaron frutos de 30 a 90 días de edad; los huevos son blanquecinos y con longitud promedio de 1 mm. La larva es ápoda y de color amarillo, con longitudes entre 1,2 y 1,5 mm y entre 10 y 12 mm en las semanas primera y sexta, respectivamente. La pupa es exarata, amarilla clara y de 7,5 mm de longitud. El adulto es café oscuro y tiene 6 mm de largo. El ciclo total duró 199 días distribuido así: huevo, 4 a 7 días; larva en el fruto, 42 a 56 días; larva en suelo, 90 días; pupa, 30 a 60 días. Los adultos emergieron entre 20 y 30 días en la época lluviosa y en laboratorio sobrevivieron hasta 435 días después de su emergencia.

Virulence of entomopathogenic nematodes to larvae of the guava weevil, Conotrachelus psidii (Coleoptera: Curculionidae), in laboratory and greenhouse experiments

Abstract The guava weevil, Conotrachelus psidii, is a major pest of guava in Brazil and causes severe reduction in fruit quality. This weevil is difficult to control with insecticides because adults emerge over a long period, and larvae develop to the fourth-instar inside the fruit and move to the soil for pupation. We assessed the virulence of entomopathogenic nematodes to fourth-instar larvae in soil by comparing their susceptibility to nine species or strains: Heterorhabditis bacteriophora HP88, H. baujardi LPP7, and LPP1, H. indica Hom1, Steinernema carpocapsae All and Mexican, S. feltiae SN, S. glaseri NC, and S. riobrave 355. In petri dish assays with sterile sand at a concentration of 100 infective juveniles (IJs) of a given nematode species/strain, larval mortality ranged from 33.5 to 84.5%, with the heterorhabditids being the most virulent. In sand column assays with H. baujardi LPP7, H. indica Hom1, or S. riobrave 355 at concentrations of 100, 200, and 500 IJs, mortality was greater than the control only for H. baujardi (62.7%) and H. indica (68.3%) at the highest concentration. For H. baujardi LPP7 in a petri dish assay, the time required to kill 50 and 90% of the larvae (LT50 and LT90) for 100 IJs was 6.3 and 9.9 days, whereas the lethal concentration required to kill 50 and 90% of the larvae (LC50 and LC90) over 7 days was 52 and 122.2 IJs. In a greenhouse study with guava trees in 20-L pots, 10 weevil larvae per pot, and concentrations of 500, 1000 or 2000 IJs, H. baujardi LPP7 caused 30 and 58% mortality at the two highest concentrations. These results show that H. baujardi is virulent to fourth-instar larvae and has potential as a biological control agent in IPM programs.

Les insectes nuisibles au goyavier (Psidium guajavaL. : Myrtaceae) en Amazonie péruvienne

Introduction. The guava tree, Psidium guajava, Myrtaceae, is a native fruit tree of the neotropical area. It is very common in all the intertropical zone and used in agroin- dustry to produce juice, nectar, sorbet, etc. To inventory the pests of the guava tree, a survey was done in different localities of Peruvian Amazonia where this fruit tree develops in a rus- tic, often subspontaneous, way. Materials and methods. Insect larvae and adults were col- lected in Peru on various parts of guava trees. Caterpillars were reared on the substrate cor- responding to their feeding mode. The fruits with larvae were followed in the laboratory until the pupa formation. A specific experiment made it possible to determine the rates of infesta- tion and the number of larvae per fruit of Anastrepha striata and Conotrachelus psidii. The collected insects were identified by taxonomists. Results and discussion. A full amount of 36 species associated with the guava tree were recorded, the most harmful being the dipteran Anastrepha striata Schiner, the coleopteran Conotrachelus psidii Marshall, and the lepi- dopteran Timocratica albella Zeller. A. striata and C. psidii attack the fruit. In one of the plan- tations visited, 56.2% of the fruits were attacked by these two species. Conclusion. Several species presented in this work are mentioned for the first time in Peru and four, new to sci- ence, are in the process of being described, or giving rise to a publication. Peru / Amazonia / Psidium guajava / pest insects / collections / identification Les insectes nuisibles au goyavier (Psidium guajava L. : Myrtaceae) en Amazonie peruvienne.