Host Preferences of Telenomus podisi (Hymenoptera: Scelionidae): Parasitism on Eggs of Dichelops melacanthus, Euschistus heros, and Podisus nigrispinus (Hemiptera: Pentatomidae)
Abstract:Successful biological control requires detailed knowledge about host preferences of the released parasitoid, because the presence of alternative hosts may affect the control of the target pest. The objective of this work was therefore to evaluate host preferences of Telenomus podisi Ashmead among the eggs of three stink bug species: Dichelops melacanthus Dallas, Euschistus heros Fabricius, and Podisus nigrispinus Dallas (Heteroptera: Pentatomidae). Three independent experiments were carried out to study host p… Show more
“…Thus, the possible better nutritional qualities of E. heros eggs over D. melacanthus eggs could be a plausible explanation to the higher performance of T. urichi in E. heros eggs, which exhibited higher number of parasitized eggs, greater emergence rate, and shorter time of egg-adult development, as well as the development of larger parasitoid adults (greater body length and greater wing length and width) when compared to results from D. melacanthus eggs. Even though, better nutritional value is frequently related to host size, this might not be applied to our results since E. heros eggs (0.83 mm width × 0.91 mm length) are smaller than D. melacanthus eggs (0.82 mm width × 0.98 mm length) 25 . Therefore, it is important to mention that host quality can vary not only with egg size but also with other factors such as host species 40 .…”
Section: Discussionmentioning
confidence: 90%
“…The arenas were adapted from those previously described in literature 24 , composed of polyethylene bottles (4 cm high and 2 cm in diameter) and two plastic microtubes (12 mm diameter × 75 mm height) arranged equidistant at the bottom of the bottle and a microtube (12 mm diameter × 75 mm height) arranged at the top of the arena (Fig. 1 ) 25 . Figure 1 Arenas used in the host preference test of the parasitoid Trissolcus urichi 25 .…”
Section: Methodsmentioning
confidence: 99%
“…1 ). Four mated T. urichi females (≤ 48 h old, mated with no previous parasitism experience) were released at the top of the arena (one female to every 40 eggs), for a period of 24 h, according to the methodology described in literature 24 for evaluation of host preference of Trichogramma parasitoids and later adapted 25 for evaluation of host preference in parasitoids of the genus Telenomus . A proportion of one parasitoid female was used for each 40 host eggs.…”
Section: Methodsmentioning
confidence: 99%
“…For each parasitoid, morphometric measurements of the right anterior wing length and width, right posterior tibia length, and body length (head to the end of the abdomen) were performed, according the standardized quality control procedures established by the International Organization of Biological Control (Global IOBC Working Group: ‘Quality Control of Mass Reared Arthropods’) 26 . For the evaluation of these morphological characters, each specimen was photographed with a stereoscopic microscope (Leica Application Suite – Version 1.6.0) and the morphometry measured using Image J (Version 1.47) 25 .…”
Section: Methodsmentioning
confidence: 99%
“…Euschistus heros and D. melacanthus eggs; which have the average size of 0.83 mm width × 0.91 mm length for E. heros eggs and 0.82 mm width × 0.98 mm length for D. melacanthus eggs 25 ; were counted (40 eggs from each host) and placed on cards (1 cm × 6 cm), and introduced into each tube on opposite sides of the arena (Fig. 1).…”
Section: Trissolcus Urichi Host Preference Between Eggs Of E Heros Amentioning
Species of the genus Trissolcus are effective as egg parasitoids of Euschistus heros and can potentially be used in a multispecies pest management approach. However, in order to successfully use those biocontrol agents in the field, previous detailed knowledge about their life history are necessary. therefore, we evaluate some biological characteristics of Trissolcus urichi on Euschistus heros and Dichelops melacanthus eggs. Three independent experiments were performed: (1) T. urichi host preference between E. heros and D. melacanthus eggs. (2) T. urichi eggs-adult period (days), number of parasitized eggs in 24 h, emergence rate (%) and sex ratio of the parasitoid in E. heros and D. melacanthus eggs. (3) Morphometric characteristics of T. urichi grown on E. heros and D. melacanthus eggs. Trissolcus urichi preferred to parasitize E. heros eggs, exhibiting a higher number of parasitized eggs, higher rate of emergence (%) and faster development, as well as producing progeny of larger size than the parasitoids emerged from eggs of D. melacanthus in relation to body length, wing length and width. thus, it can be concluded that T. urichi had better performance on E. heros eggs, although the parasitoid had also acceptable parasitism capacity and development in D. melacanthus eggs. Stink bugs are one of the most important groups of insects that cause yield losses in soybean (Glycine max) production in Brazil, Argentina and Uruguay 1. Not only have they damage soybean in South America but also in Arkansas and other states in the Mid-South of the United States 2. Because these insects feed directly on the soybean pods they seriously affect both yield and bean quality 1,3. Among the recorded stink bugs from soybean fields, there have been at least 54 different species belonging to the family Pentatomidae 4. The relative economic importance of each species might vary according to each country or its region 5. However, of the many species of stink bug, the Neotropical Brown Stink Bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) is the most frequent pest of field crops, mainly in the central region of Brazil at latitudes between 0° and 23°6. In addition, more recently, the Green-Belly Stink Bug, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), has become more abundant, increasing its significance to soybean and maize (Zea mays) production in the Neotropical region, especially in Brazil 7. This increase is mostly a consequence of the adopted production system in which soybean is cropped during summer immediately followed by maize in autumn. The resulting continuous food supply to the insects throughout the year, known as green bridge, has favored D. melacanthus outbreaks 8 .
“…Thus, the possible better nutritional qualities of E. heros eggs over D. melacanthus eggs could be a plausible explanation to the higher performance of T. urichi in E. heros eggs, which exhibited higher number of parasitized eggs, greater emergence rate, and shorter time of egg-adult development, as well as the development of larger parasitoid adults (greater body length and greater wing length and width) when compared to results from D. melacanthus eggs. Even though, better nutritional value is frequently related to host size, this might not be applied to our results since E. heros eggs (0.83 mm width × 0.91 mm length) are smaller than D. melacanthus eggs (0.82 mm width × 0.98 mm length) 25 . Therefore, it is important to mention that host quality can vary not only with egg size but also with other factors such as host species 40 .…”
Section: Discussionmentioning
confidence: 90%
“…The arenas were adapted from those previously described in literature 24 , composed of polyethylene bottles (4 cm high and 2 cm in diameter) and two plastic microtubes (12 mm diameter × 75 mm height) arranged equidistant at the bottom of the bottle and a microtube (12 mm diameter × 75 mm height) arranged at the top of the arena (Fig. 1 ) 25 . Figure 1 Arenas used in the host preference test of the parasitoid Trissolcus urichi 25 .…”
Section: Methodsmentioning
confidence: 99%
“…1 ). Four mated T. urichi females (≤ 48 h old, mated with no previous parasitism experience) were released at the top of the arena (one female to every 40 eggs), for a period of 24 h, according to the methodology described in literature 24 for evaluation of host preference of Trichogramma parasitoids and later adapted 25 for evaluation of host preference in parasitoids of the genus Telenomus . A proportion of one parasitoid female was used for each 40 host eggs.…”
Section: Methodsmentioning
confidence: 99%
“…For each parasitoid, morphometric measurements of the right anterior wing length and width, right posterior tibia length, and body length (head to the end of the abdomen) were performed, according the standardized quality control procedures established by the International Organization of Biological Control (Global IOBC Working Group: ‘Quality Control of Mass Reared Arthropods’) 26 . For the evaluation of these morphological characters, each specimen was photographed with a stereoscopic microscope (Leica Application Suite – Version 1.6.0) and the morphometry measured using Image J (Version 1.47) 25 .…”
Section: Methodsmentioning
confidence: 99%
“…Euschistus heros and D. melacanthus eggs; which have the average size of 0.83 mm width × 0.91 mm length for E. heros eggs and 0.82 mm width × 0.98 mm length for D. melacanthus eggs 25 ; were counted (40 eggs from each host) and placed on cards (1 cm × 6 cm), and introduced into each tube on opposite sides of the arena (Fig. 1).…”
Section: Trissolcus Urichi Host Preference Between Eggs Of E Heros Amentioning
Species of the genus Trissolcus are effective as egg parasitoids of Euschistus heros and can potentially be used in a multispecies pest management approach. However, in order to successfully use those biocontrol agents in the field, previous detailed knowledge about their life history are necessary. therefore, we evaluate some biological characteristics of Trissolcus urichi on Euschistus heros and Dichelops melacanthus eggs. Three independent experiments were performed: (1) T. urichi host preference between E. heros and D. melacanthus eggs. (2) T. urichi eggs-adult period (days), number of parasitized eggs in 24 h, emergence rate (%) and sex ratio of the parasitoid in E. heros and D. melacanthus eggs. (3) Morphometric characteristics of T. urichi grown on E. heros and D. melacanthus eggs. Trissolcus urichi preferred to parasitize E. heros eggs, exhibiting a higher number of parasitized eggs, higher rate of emergence (%) and faster development, as well as producing progeny of larger size than the parasitoids emerged from eggs of D. melacanthus in relation to body length, wing length and width. thus, it can be concluded that T. urichi had better performance on E. heros eggs, although the parasitoid had also acceptable parasitism capacity and development in D. melacanthus eggs. Stink bugs are one of the most important groups of insects that cause yield losses in soybean (Glycine max) production in Brazil, Argentina and Uruguay 1. Not only have they damage soybean in South America but also in Arkansas and other states in the Mid-South of the United States 2. Because these insects feed directly on the soybean pods they seriously affect both yield and bean quality 1,3. Among the recorded stink bugs from soybean fields, there have been at least 54 different species belonging to the family Pentatomidae 4. The relative economic importance of each species might vary according to each country or its region 5. However, of the many species of stink bug, the Neotropical Brown Stink Bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) is the most frequent pest of field crops, mainly in the central region of Brazil at latitudes between 0° and 23°6. In addition, more recently, the Green-Belly Stink Bug, Dichelops melacanthus (Dallas) (Hemiptera: Pentatomidae), has become more abundant, increasing its significance to soybean and maize (Zea mays) production in the Neotropical region, especially in Brazil 7. This increase is mostly a consequence of the adopted production system in which soybean is cropped during summer immediately followed by maize in autumn. The resulting continuous food supply to the insects throughout the year, known as green bridge, has favored D. melacanthus outbreaks 8 .
The egg-parasitoid wasp Telenomus podisi has received attention as a biological-control agent for one of the most important soybean pests in Brazil, the stink bug Euschistus heros. As yet, no studies have conclusively established strategies for the release of T. podisi. We developed a computational model employing cellular automata to investigate release strategies for T. podisi in soybean crops, in order to optimize the use of these wasps in managing E. heros. A computational model was developed, using cellular automata in the C programming language and assuming a two-dimensional grid of cells corresponding to a soybean eld. The biological dynamics of E. heros and T. podisi were programmed. The following parameters for release strategy were investigated: release mode, number of releases, number of parasitoids per hectare per release, and spacing between release points or strips. The sensitivities of the release and movement parameters were analyzed. The release strategies capable of maintaining an E. heros population below the Economic Threshold level involved releasing a total of at least 15,000 female parasitoids per hectare, in three or four releases of 5,000 or more. A 25-m spacing between release points or strips was indicated. The theoretical results produced by the computational model are expected to guide future eld studies to improve T. podisi release plans for managing E. heros in soybeans.
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