Life table study of Rachiplusia nu (Lepidoptera: Noctuidae) on different food sources and artificial diet.

Rachiplusia nu Guenée is a polyphagous species able to develop on several cultivated and non-cultivated host plants. However, basic life history information about this pest on hosts is scarce. In this study, R. nu larvae did not survive on leaves of non-Bt corn, wheat, Bt cotton that expresses proteins Cry1Ac+Cry2Ab2 or on Intacta2 Xtend soybean that expresses the Cry1A.105/Cry2Ab2/Cry1Ac proteins. Rachiplusia nu showed a viable egg-to-adult biological cycle (54%-66.3%) on non-Bt soybean, sunflower, canola, vetch, Persian clover, alfalfa, bean, and forage turnip hosts, similar to larvae raised on the artificial diet. In addition, R. nu was unable to complete larval development on non-Bt cotton, and only 45.2% of R. nu larvae reached the pupal stage when fed leaves of intacta RR2 PRO soybean that expresses the Cry1Ac protein. Larval and pupal mass of surviving insects on Cry1Ac soybean leaves were also lower (larval: 0.104 g; pupal: 0.099 g) in relation to other food sources (larval: 0.165-0.189 g; pupal: 0.173-0.192 g). The total fecundity of R. nu on Cry1Ac soybean leaves was ≈65% lower in relation to other food sources. This fact caused ≈60% the net reproductive rate (Ro) and intrinsic rate of increase (rm) when compared to other food sources. Our findings indicate that the Cry1Ac soybean negatively affects the biological parameters of R. nu. Non-Bt soybean, sunflower, canola, vetch, Persian clover, alfalfa, bean, and forage turnip are viable food sources for the survival and development of R. nu.

Different Protein Sources of Larval Diet on the Rearing of Anastrepha fraterculus (Diptera: Tephritidae): Biological and Nutritional Analyses.

Anastrepha fraterculus (Diptera: Tephritidae) is considered an important pest in Neotropical countries. The laboratory rearing of this species should reproduce conditions in nature; thus, special attention is required to the nutritional quality of diets for larval development. Protein components (wheat germ) are costly and account for most production costs in lab insect rearing. In this sense, this work aimed to identify ingredients to replace wheat germ, without compromising diet quality for the lab rearing of A. fraterculus. We tested diets composed of whole rice flour, corn flour, and a mixture of whole wheat flour + soybean flour as substitutes for wheat germ as well as a raw wheat germ diet, considered the control. The protein sources used in the larval diet influenced the biological performance of both the larval and adult stages of A. fraterculus during six generations. The diet containing corn flour and wheat germ showed similar results in the different developmental parameters. The diet with rice flour also provided adequate biological development for A. fraterculus throughout its life cycle and was nutritionally similar to the control. As it is local product, rice flour can replace wheat germ (costly imported product) in artificial diets for A. fraterculus, reducing production costs by roughly 30% without compromising the biological and nutritional parameters of the insects. Faced with this, the rice flour can be considered suitable for the mass rearing of A. fraterculus in the laboratory.

Fasting-induced activity changes in MC3R neurons of the paraventricular nucleus of the thalamus.

The brain controls energy homeostasis by regulating food intake through signaling within the melanocortin system. Whilst we understand the role of the hypothalamus within this system, how extra-hypothalamic brain regions are involved in controlling energy balance remains unclear. Here we show that the melanocortin 3 receptor (MC3R) is expressed in the paraventricular nucleus of the thalamus (PVT). We tested whether fasting would change the activity of MC3R neurons in this region by assessing the levels of c-Fos and pCREB as neuronal activity markers. We determined that overnight fasting causes a significant reduction in pCREB levels within PVT-MC3R neurons. We then questioned whether perturbation of MC3R signaling, during fasting, would result in altered refeeding. Using chemogenetic approaches, we show that modulation of MC3R activity, during the fasting period, does not impact body weight regain or total food intake in the refeeding period. However, we did observe significant differences in the pattern of feeding-related behavior. These findings suggest that the PVT is a region where MC3R neurons respond to energy deprivation and modulate refeeding behavior.

Mating behavior and oviposition of Palpita forficifera (Lepidoptera: Crambidae).

Palpita forficifera Munroe, 1959 (Lepidoptera: Crambidae) is considered the main pest of the olive tree (Olea europaea L., Oleaceae) in Brazil and Uruguay. The aim of this work was to study the mating and oviposition behavior of P. forficifera in the field and laboratory. In the field, the sex emitting the mating pheromone was determined and in the laboratory, the rate of emergence of males and females; the age, time and duration of mating; number of copulations and oviposition time of P. forficifera were recorded. The field results showed that it was possible to capture up to five males per trap in just one night in traps with the presence of female P. forficifera. Copulation occurs between the seventh and twenty-third day of life and is most frequent during the third and sixth hours of scotophase. The average duration of the first copulation was 174 min, with 35% of couples recopulating, and there were cases of up to five copulations. Oviposition times were concentrated between 20:00 and 02:00. The results obtained provide insight into the reproductive behavior of P. forficifera and are useful for future studies aimed at identifying the sex pheromone to improve monitoring of the pest in olive orchards.

Effects of mixtures of arrestants, dislodgers, and phagostimulants with synthetic insecticides on green-belly stink bug: walking behavior assessments, physicochemical interactions, and laboratory and field trials.

The green-belly stink bug (Diceraeus melacanthus Dallas (Hemiptera: Pentatomidae)) is a key pest of corn-soybean crop systems and the management of this pest is difficult due to behavioral characteristics. However, products that alter its behavior, such as arrestants, dislodgers, and phagostimulants, have been used in an attempt to improve the effectiveness of chemical control. In this study, the effect of these products on the walking behavior of nymphs and adults of D. melacanthus was initially evaluated through computational behavioral tracking (Ethovision system). Adults of D. melacanthus exposed to the dislodgers Creolin Pearson and Quimifol S450 (sulfur) significantly increased the distance covered and the walking speed. On the other hand, the only treatment that significantly affected the walking behavior of nymphs was the treatment with soy milk (phagostimulant). The physical-chemical analyses indicated considerable changes in the pH and electrical conductivity of mixtures of such products with insecticides from different chemical groups, as well as lack of homogeneity (physical incompatibility). Nevertheless, none of the products tested improved the control efficacy of an insecticide based on imidacloprid + beta-cyfluthrin, either in laboratory tests (contact bioassay) or in tests conducted in corn crops during 2 crop harvests. Thus, the association of these products in a tank mixture does not increase the control levels of D. melacanthus in post-emergence of maize and may have an antagonistic effect in some associations.

Reproductive Biology of Trichopria anastrephae (Hymenoptera: Diapriidae), a Biological Control Agent of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae).

Hymenopteran parasitoids, like any other insect, employ strategies to ensure their reproduction. Understanding these strategies is important for ecological purposes, but also to improve mass rearing of biological control agents. Here, we describe mating strategies used by the pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae), a potential biocontrol agent, that has been considered for augmentative releases for management of the invasive pest species Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). We studied the emergence pattern of males and females of T. anastrephae and the effects of parental ae on offspring number and sex ratio. Polygamy was also studied and its effects on parasitism and offspring production were described. Adults from this species emerge in the first hours of photophase, and males emerge before females, demonstrating that T. anastrephae is a protandrous species. Parasitoid age when first mated influences the parasitism and sex ratio. Younger females result in a higher number of offspring (8.16 parasitoids/day), while older males result in a more female-biased sex ratio of offspring (64% females). Both males and females are polygamic, and the order in which a female is mated by the male affects parasitism, viability of parasitized pupae, and sex ratio of offspring, with the first female performing the highest parasitism and sex ratio (63.83 and 61% of females, respectively), but the lowest viability (92.92%). Females that are allowed to mate multiple times generate lower numbers of offspring (113.05 parasitoids) when compared to virgin or single-mated females (135.20 and 130.70 parasitoids, respectively), but the highest sex ratio (49% of females). Data present in this study and how it can be used to improve parasitoid rearing and field releases of T. anastrephae, in biological control programs for D. suzukii are discussed.

The use of toxic baits for the suppression of Mediterranean fruit fly in mango orchards.

Ceratitis capitata (Wiedemann, 1824) is an insect of major economic importance in the mango orchards of the submedium of the São Francisco River Valley, the main area of mango production and exportation in Brazil. To provide alternatives for the management of C. capitata, toxic baits based on alpha-cypermethrin (Gelsura®) and spinosad (Success® 0.02 CB) were evaluated in three commercial mango experiments during two consecutive harvests: 2016/2017 (experiment 1 - area 1) and 2017/2018 (experiment 2 -area 2 and experiment 3 - area 3). According to the results, there was a large reduction in the infestation of C. capitata after five sequential applications of the alpha-cypermethrin (6 g.ha-1) and spinosad (0.38 g.ha-1) toxic baits performed at seven-day intervals during mango fruit ripening in all experiments and years (harvest) evaluated. Compared with the untreated plots, the plots with alpha-cypermethrin and spinosad applications showed a significant reduction in the damage induced (fallen fruits and/or on trees) by C. capitata. The management of C. capitata in mango orchards can include the use of the toxic bait based on alpha-cypermethrin, which represents an alternative to rotate with spinosad toxic bait in the São Francisco River Valley.

Novel Lactone-Based Insecticides and Drosophila suzukii Management: Synthesis, Potential Action Mechanisms and Selectivity for Non-Target Parasitoids.

Drosophila suzukii, an invasive insect pest, poses a significant threat to various fruit crops. The use of broad-spectrum insecticides to control this pest can reduce the effectiveness of biological control agents, such as the parasitoid Trichopria anastrephae. Here, we evaluated the toxicity of newly synthesized lactone derivatives on D. suzukii and their selectivity towards T. anastrephae. We used in silico approaches to identify potential targets from the most promising molecules in the D. suzukii nervous system and to understand potential differences in susceptibilities between D. suzukii and its parasitoid. Of the nine molecules tested, (rac)-8 and compound 4 demonstrated efficacy against the fly. Exposure to the estimated LC90 of (rac)-8 and compound 4 resulted in a mortality rate of less than 20% for T. anastrephae without impairing the parasitoid's functional parasitism. The in silico predictions suggest that (rac)-8 and compound 4 target gamma amino butyric acid (GABA) receptors and transient receptor potential (TRP) channels of D. suzukii. However, only the reduced interaction with TRP channels in T. anastrephae demonstrated a potential reason for the selectivity of these compounds on the parasitoid. Our findings suggest the potential for integrating (rac)-8 and compound 4 into D. suzukii management practices.

Spatial and temporal dispersion of Doryctobracon areolatus (Szépligeti) (Hymenoptera: Braconidae) in orchards infested with Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae).

Doryctobracon areolatus (Szépligeti) is an endoparasitoid and promising fruit fly control agent. The objective of the study was to determine the spatial (horizontal and vertical) and temporal dispersion of D. areolatus in the field. To evaluate the horizontal and temporal dispersion, two peach orchards were selected. In each orchard, 50 points were marked at different distances from the central point, from where 4,100 couples of D. areolatus were released. Four hours after release, parasitism units (PU) (3 per point) were fixed to the trees at a height of 1.5 m from the ground. The PUs were composed of ripe apples artificially infested with second instar larvae of Anastrepha fraterculus (30 larvae/fruit). For the evaluation of vertical dispersion, in an olive orchard six points were selected (trees of ≈4 m in height). Each tree was divided into three heights in relation to the ground (1.17, 2.34, and 3.51 m). Doryctobracon areolatus was able to disperse horizontally at a distance >60 m from the release point. However, the highest parasitism rates [15-45% (area 1); 15-27% (area 2)] were observed up to 25 m. Higher percentages of parasitism and of recovered offspring occur in the first days after the release of the parasitoid (2 DAR). As for vertical dispersion, D. areolatus parasitized A. fraterculus larvae up to the highest attachment height of the evaluated PUs (3.51). The results showed the potential use of D. areolatus in the management of fruit flies in the field.

Association of growth-regulating insecticides and limonoid-based formulations: physicochemical compatibility and toxicity against Spodoptera frugiperda (Lepidoptera: Noctuidae).

The objective of this study was to evaluate the physicochemical compatibility of mixtures of synthetic and botanical limonoid-based insecticides, as well as the toxicity of these associations, in the management of Spodoptera frugiperda (J.E. Smith) under laboratory and field conditions. For this, the associations of 4 commercial botanical insecticides based on neem registered in Brazil (Azamax, Agroneem, Azact CE, and Fitoneem) were tested with synthetic insecticides from the group of growth regulators (IGRs [triflumuron, lufenuron, methoxyfenozide and tebufenozide]). When mixed, all combinations caused a significant reduction in the pH of the mixture and a significant increase in electrical conductivity. However, all tested combinations showed similar stability behavior to the negative control (distilled water), which demonstrated their physicochemical compatibility. Furthermore, in laboratory and field bioassays, mixtures of IRGs with limonoid-based formulations provided satisfactory effects in the management of S. frugiperda. However, binary mixtures of insecticide Intrepid 240 SC with Azamax or Azact CE (at LC25 previously estimated) showed the highest toxicities on S. frugiperda larvae in laboratory bioassays and damage reduction caused by S. frugiperda in a 2-yr field experiments. Therefore, mixtures of IGRs with limonoid-based botanical insecticides are promising alternatives for the management of S. frugiperda and important component of integrated pest management and insect resistance management programs.

Search hours for food attractant by Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae) adults in guava orchards.

Anastrepha fraterculus (Wiedemann, 1830) and Ceratitis capitata (Wiedemann, 1824) are considered the main pests of Brazilian fruit production. Understanding the behavior of species is of great importance for the success of management strategies. This study was to determine the period and search time by attractive food for A. fraterculus and C. capitata adults by using three commercial food attractants: BioAnastrepha™ 5%; Isca Samaritá Tradicional™ 5% and Ceratrap™ 1.5%. The largest catches of A. fraterculus and C. capitata adults in McPhail traps occurred during the day between 6:30 am and 6:30 pm for both species. The BioAnastrepha™ food attractant provided the largest catches compared to Isca Samaritá Tradicional™ and Ceratrap™. In addition, there was a higher prevalence of capturing females than males, for both flies' species. The period of largest search activity for food attractant was observed from 12h:31 pm to 04:30 pm for A. fraterculus and C. capitata, time of greatest temperature on the day. The definition of the period of largest activity of A. fraterculus and C. capitata adults in the field helps in the elaboration of management strategies to be adopted.

Lethal and sublethal effects of toxic bait formulations on Doryctobracon areolatus (Hymenoptera: Braconidae) and implications for integrated fruit fly management.

The use of toxic baits has become one of the main methods of management of fruit flies in Brazil. The application of toxic baits may cause side effects on the native parasitoid Doryctobracon areolatus (Hymenoptera: Braconidae). Based on the results, formulations made from the food attractants 3% Biofruit, 1.5% Ceratrap, 1.25% Flyral, 3% Isca Samaritá, 3% Isca Samaritá Tradicional, and 7% sugarcane molasses associated with the Malathion 1000 EC and the ready-to-use toxic bait Gelsura (containing the active ingredient alpha-cypermethrin) were classified as harmful (class 4) to D. areolatus (mortality > 85% at 96 HAE). In contrast, for toxic baits formulated with insecticide phosmet, the mortality ranged from 38% to 72%, classified as slightly harmful or moderately harmful. However, when phosmet was added to the 3% Samaritá Tradicional bait, the mortality was only 3.9% (class 1-harmless), similar to the toxicity observed for the Success 0.02 CB ready-to-use bait (0.24 g a.i. spinosad/l) (<5% mortality). Although toxic baits were formulated with spinosyn-based insecticides, all toxic bait formulations were classified as harmless or slightly harmful (<50% mortality) to D. areolatus, with the exception of 1.5% Ceratrap + spinetoram and 7% Sugarcane molasses + spinosad (≈ 60% mortality-moderately harmful). In addition, these formulations did not show sublethal effects in reducing the parasitism and emergence rate of the F1 generation of D. areolatus in A. fraterculus larvae. The results serve as a basis for the correct use of toxic food baits without affecting the biological control.

Differential response to the South American rice water weevil (Coleoptera: Curculionidae) damage of rice cultivars with contrasting levels of resistance: implications for field management.

BACKGROUND: Oryzophagus oryzae (Costa Lima) (Coleoptera: Curculionidae) is a major pest of flooded rice paddies throughout South America, and species with very similar life histories are present in many rice-producing regions of the world (collectively rice water weevils, RWWs). The damage caused by RWW larvae on rice cultivars with contrasting levels of resistance ('BRS Pampa CL'= 'Pamp': susceptible, 'BRS Atalanta' = 'Atal': resistant-antibiosis) was evaluated in two consecutive years in the field under seven infestation levels: 0, 2, 4, 6, 8, 10 and 20 adult couples per cage with plants. RESULTS: Higher densities of adults increased the number of leaf-feeding scars and larvae on roots, respectively, at the rate ≤2.14 and 2.75 in Pamp and 2.23 and 2.48 in Atal, with the total number of larvae generated being lower in Atal. Grain yield was negatively impacted with increasing larval density on the roots, mainly by decreasing root volume and the number of grains per panicle. Root injury intensity and yield loss showed a nonlinear relationship. It was found that significant yield losses occurred with 8.37 larvae per plant in Pamp and 9.80 larvae per plant in Atal CONCLUSION: The results provided the first evidence of a tolerance limit for RWW larval damage that, even though similar between cultivars of contrasting resistance, corresponds to twice the current conventional level for larval control in Brazil. We also discuss here the potential of applying tolerance limits to manage the RWW adult population in rice fields. © 2022 Society of Chemical Industry.

Selection of Strains of Trichogramma foersteri and Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) for the Control of Palpita forficifera (Lepidoptera: Crambidae).

Palpita forficifera Munroe 1959 is a lepidopteran pest native to the Neotropical region and has been causing damage to olive tree crops in Brazil and Uruguay. The use of egg parasitoids of the genus Trichogramma may be a viable and sustainable alternative to pest management. The objective of the present work was to select species and/or strains of Trichogramma as possible agents of control for P. forficifera. Selections were made from five strains of Trichogramma foersteri Takahashi (R1, R2, R3, R4, and R5) collected in olive orchards of southern Brazil and four strains of Trichogramma pretiosum Riley (AC, PR, MJU, and RVI) from laboratory rearings. The strains of T. foersteri presented the longest periods from egg to adult (≈ 11.5 days) when compared to T. pretiosum (≈ 9.5 days). However, T. foersteri provided, in general, the highest daily percentage of parasitized P. forficifera eggs and, consequently, a higher rate of parasitism (between 50 and 69%) in relation to those of T. pretiosum (variation from 7 to 20%). In addition, T. foersteri provided a higher emergence rate (above 90%), with a sex ratio close to 1.0. However, all strains of T. pretiosum were longer-lived compared to adults of T. foersteri. From the biological parameters evaluated, two distinct groups were formed between T. foersteri and T. pretiosum. In general, T. foersteri has better potential for controlling P. forficifera, demonstrating its potential for use in field multiplication and release programs for the management of the olive larvae.

Sublethal effects of growth-regulating insecticides of synthetic and botanical origins on the biological parameters of Spodoptera frugiperda (Lepidoptera: Noctuidae).

The objective of this study was to evaluate the effects of growth-regulating insecticides of synthetic (e.g., Certero 480 SC, Intrepid 240 SC, Match EC and Mimic 240 SC) and botanical origins (e.g., Azamax 1.2 EC, Agroneem 850 EC, Azact 2.4 EC and Fitoneem 850 EC) on the biological parameters and fertility life table of Spodoptera frugiperda (J.E. Smith) under laboratory conditions. Larvae were fed insecticides that were incorporated into artificial diets. To develop the fertility life table, the following biological parameters were evaluated: survival at 7 days after infestation (d.a.i) and survivorship at adult eclosion, duration of the neonate-to-adult eclosion period, larval and pupal weights and total fecundity (number of total eggs per female). The results indicated that S. frugiperda neonates surviving LC25 or LC50 concentrations of the evaluated insecticides showed longer larval and egg-to-adult periods, lower larval and pupal weights and reduced fecundity, when compared to the control treatment. Larvae exposed to Azamax at LC25 or LC50 concentrations showed the greatest increase in generation duration (75 d). In addition, S. frugiperda adults emerged from pupae when larvae reared on an artificial diet containing growth regulating insecticides of synthetic and botanical origins produced fewer females per female per generation (Ro). As well as, lower rates of natural population increase per day (rm) compared to insects fed the control diet. Our findings indicated that, neem-derived products and growth-regulating insecticides of synthetic origin may be employed within integrated management strategies that aim to keep populations of S. frugiperda below levels that cause economic damage. Similarly, they offer alternatives for insecticide resistance management programs.

Toxicity of Bacillus sp. (Bacillales: Bacillaceae) on the fungus gnats, Bradysia aff. ocellaris larvae (Diptera: Sciaridae)

Bacillus thuringiensis (Bt) Berliner has potential for use in insect management. Its use can be an alternative for the management of Bradysia aff. ocellaris (Comstock), considered one of the main strawberry pests in a soilless system. Therefore, the objective of this work was to evaluate the toxicity of different bacteria on B. aff. ocellaris in laboratory and greenhouse bioassays. The following isolates were used in the experiments: Bacillus circulans (Bc), B. thuringiensis var. oswaldo cruzi (Bto) or B. thuringiensis var. israelensis (Bti) and B. thuringiensis var. kurstaki (Btk) In the laboratory, B. aff. ocellaris larvae showed high susceptibility to Bti isolate (92 % mortality) 14 days after treatment exposure (DAET). In contrast, the isolates Bc, Bto, and Btk showed less than 32 % mortality, not differing from the control treatment (water ­ 22 % mortality). According to the concentration-response curves the values of lethal concentration LC50 and LC90 were 4 x 106 CFU.mL-1 and 4 x 1015 CFU.mL-1. By applying Bti (4 × 1012 CFU.mL-1) at the base of strawberry plants growing in plastic pots containing commercial plant substrate, a reduction of 26 % in the emergence of B. aff. ocellaris was observed. According to these results, the Bti isolate is considered promising for the formulation of bioinsecticides based on Bt for the management of B. aff. ocellaris in strawberry culture.

Essential Oils as a Source of Ecofriendly Insecticides for Drosophila suzukii (Diptera: Drosophilidae) and Their Potential Non-Target Effects.

The spotted wing drosophila (Drosophila suzukii) is one of the main invasive pests of small fruits in the world. Thus, 19 essential oils (EOs) were selected to analyze the effects through toxicity and repellency on oviposition and D. suzukii adults. In addition, their lethal and sublethal effects on the pupal endoparasitoid Trichopria anastrephae were evaluated. The EOs of C. flexuosus and Mentha spp. had the highest toxicity observed in the topical application bioassay for D. suzukii. In contrast, the EOs of C. verum, C. citratus QT citratus, and C. winterianus showed the highest toxicity in the ingestion bioassay for D. suzukii. The dry residues of C. verum and C. citratus QT citratus reduced the oviposition of D. suzukii. In the repellency bioassays, the 19 EOs analyzed repelled ≅ 90% of the D. suzukii females. All EOs evaluated using the LC90 values of the products provided mortality of less than 20% of T. anastrephae adults and did not cause a reduction in the parasitism of surviving T. anastrephae females. We conclude that the EOs evaluated have the potential to be used in the management of D. suzukii. They can also serve as selective active ingredients for the formulation and synthesis of new biopesticides.

Biological Activity of Insecticides Against Bradysia ocellaris Larvae (Diptera: Sciaridae): A New Pest of Strawberry Crops.

Black fungus gnat larvae are one of the primary insect pests in greenhouse and nursery crops, and Bradysia ocellaris (Comstock) (Diptera: Sciaridae) is one common pest species. This pest is difficult to control in Brazil because of the absence of registered insecticides. The aim of this work was to evaluate the effects of some insecticides on B. ocellaris larvae. We also verified that the insect growth regulator novaluron caused the deformation of B. ocellaris. Of the insecticides evaluated, malationa, and thiamethoxam showed high mortality rate (96 and 86 % respectively). Further, bioassays with acetamiprid (78 %) and novaluron (44 %) showed that the lethal concentrations (LC50) were 19.18 mg a.i.L-1 at 48h to acetamiprid and 1.24 mg a.i.L-1 at 120 h to novaluron. When larvae were fed on potato pieces treated with novaluron, independently of the dose, the mortality rate was 100 %, since no larvae could complete the development cycle. Among all evaluated insecticides, only acetamiprid and novaluron were considered effective tools for control of B. ocellaris larvae under laboratory conditions.

Population Dynamics of Heliothrips haemorrhoidalis (Thysanoptera: Thripidae) in Strawberry Cultivars in Southern Brazil.

Heliothrips haemorrhoidalis is a polyphagous thrips species that has been reported as a potential pest in strawberry cultivation in Brazil. Since it has only recently emerged as a pest species in production areas, understanding seasonal trends in the species' activity is particularly important for designing management strategies. Therefore, this study aims to investigate the influence of climate factors (temperature and relative humidity) and six strawberry cultivars ('Albion', 'Aromas', 'Camino Real', 'Monterey', 'Portola', and 'San Andreas') on the population dynamics of H. haemorrhoidalis during the 2018-2019 and 2019-2020 growing seasons in southern Brazil. The greatest peak in thrips populations in the cultivars assessed occurred between January and March (summer) in both growing seasons. The relationship between the incidence of H. haemorrhoidalis and temperature was observed to be negative during the autumn, spring, and summer months but positive during winter. Relative humidity levels above 70% had a negative influence on the abundance of insects. Populations of H. haemorrhoidalis varied between the cultivars as follows: 'Aromas' > 'Monterey' > 'San Andreas' > 'Albion' > 'Camino Real' > 'Portola'. Cross-sections of strawberry leaves showed that 'Monterey' had the highest density of nonglandular trichomes/mm2 (7.26), while 'Portola' cultivar, the greatest predominance of glandular trichomes/mm2 (12.67), which may have contributed to the incidence of H. haemorrhoidalis. The demographic information presented on H. haemorrhoidalis in strawberry cultivars provides a starting point to better understand the insect's population dynamics. These results also indicate that climatic conditions are a limiting factor for the development of H. haemorrhoidalis.

Field Assessment of Oryzophagus oryzae (Coleoptera: Curculionidae) Preference and Performance on Selected Rice Cultivars.

Plant resistance is a key strategy for the management of Oryzophagus oryzae (Costa Lima) (Coleoptera: Curculionidae), an important pest in South American rice paddies. The present study investigated the resistance of rice cultivars in terms of feeding and oviposition preference, growth, development, and biological performance of O. oryzae under natural conditions of field infestation during two consecutive rice seasons. There were no effects of the six cultivars on the feeding and oviposition preferences of O. oryzae as evaluated 5, 8, and 11 d After Flooding (DAF) of the plots, indicating the absence of antixenosis. Cultivars did not differ in terms of egg viability and larval density of first instars on the roots at 15 DAF. Significant differences were found 25 and 35 DAF when larval density per sample was high on 'BRS Pampa CL' (up to 24.5), intermediate on 'BRS Querência' and 'BRS Ligeirinho' (up to 16.1), and low on 'BRS Atalanta', 'BRS Firmeza', and 'Dawn' (up to 8.8). The cultivars 'BRS Atalanta', 'BRS Firmeza', and 'Dawn' caused malnutrition and inhibition of larval growth. These effects, typical of antibiosis, resulted in delayed pupation and emergence of adults; in addition, emerged females had body weight decreased strongly. The cultivars BRS Pampa CL, BRS Querência, and BRS Ligeirinho are susceptible, resulting in high larval populations and more suitable development of O. oryzae; antibiosis, as indicated for 'BRS Atalanta', 'BRS Firmeza', and 'Dawn', probably is the key mechanism of rice resistance to O. oryzae.