Insecticidal activity of extracts of handroanthus impetiginosus on Plutella xylostella (Lepidoptera: plutellidae) larvae.

Plutella xylostella is considered the main pest of cabbage in Brazil and the world, causing damage of up to 100%. Thus, this study evaluated the insecticidal activity of extracts obtained from the fruits, seeds, bark, leaves, and flowers of Handroanthus impetiginosus against the diamondback moth, P. xylostella larvae. The seed extract showed the highest mortality (97.0%) compared to the control treatment. The LC50 values indicated that the seed and flower extracts (0.01003 and 0.01288 mg/L respectively) assumed the highest toxicity to P. xylostella larvae after 24 h of exposure. The results of this study indicated that the seeds extract is the most promising toxic extract, with measured mortality of approximately 97.0% for P. xylostella larvae after 144 h of exposure in kale plants. Seed extract showed the best insecticidal activity. Thus, this extract can be applied to develop an insecticide based on H. impetiginosus seed.

Functional response of 3 green lacewing species (Neuroptera: Chrysopidae) to Leucoptera coffeella (Lepidoptera: Lyonetiidae).

Green lacewings (Neuroptera: Chrysopidae) are predators commonly found in coffee plantations in Brazil that can serve as important biological control agents against insect pests such as the coffee leaf miner, Leucoptera coffeella (Lepidoptera: Lyonetiidae). However, the efficacy of different lacewing species in controlling L. coffeella needs to be evaluated before they are used in augmentative biological control programs. Here, laboratory experiments were conducted to investigate the effects of the L. coffeella developmental stage on the functional response of 3 species of green lacewings: Chrysoperla externa, Ceraeochrysa cincta, and Ceraeochrysa cornuta. The attack rate, handling time, and the number of prey attacked during 24 h with different densities (1, 2, 4, 8, 16, 32, and 64 individuals) of either L. coffeella larvae or pupae were recorded for each of the 3 lacewing species. Based on logistic regression models, all 3 predators showed a Type II functional response when consuming both larvae and pupae of L. coffeella. All 3 species also had similar attack rates (0.0091 larva/h and 0.0095 pupa/h), handling times (3.5 and 3.7 h for larvae and pupae, respectively), and estimated number of prey attacked during the observation period (6.9 larvae and 6.6 pupae) for L. coffeella larvae and pupae. Therefore, our laboratory studies show that the 3 green lacewings Ch. externa, Ce. cincta, and Ce. cornuta have potential for the biological control of L. coffeella, although these results need to be confirmed under field conditions. These findings have implications for the selection of lacewings for augmentative L. coffeella biocontrol.

Within-Canopy Distribution of Stenoma catenifer (Lepidoptera: Elachistidae) Infestation in Avocado Orchards.

Native to the neotropics, the avocado seed moth Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) is a specialist pest of the family Lauraceae and considered one of the most important pests of avocados worldwide. However, little is known regarding its spatial distribution within a single tree. Therefore, we designed a study to evaluate the effects of canopy height and aspect (i.e., side of the tree) on fruit infestation by S. catenifer larvae in avocados. The study was conducted in three commercial organic avocado orchards located in São Paulo, Brazil. At each orchard, 40 fruit from 30 random trees were sampled weekly from October 2017 through February 2018, evaluating the number of fruits infested by S. catenifer larvae at three tree heights (bottom, middle, and top). In addition, fruits on the ground were also sampled. We also evaluated the effect of the side of the tree where the fruits were collected, i.e., whether they were on the side facing the east (sunrise) or the west (sunset). Within the avocado canopy, the level of fruit infestation by S. catenifer larvae was significantly higher at the top of the trees than in the middle and bottom. Fruit on the ground had lower levels of infestation than those on the tree canopy. The level of fruit infestation was also higher on the side of avocado trees facing the east (sunrise). Understanding the within-tree distribution of S. catenifer will help to better target monitoring and control activities against this pest in avocados.

Acute and Chronic Toxicity of Indoxacarb in Two Populations of Plutella xylostella (Lepidoptera: Plutellidae).

The diamondback moth, Plutella xylostella (Linnaeus, 1758), is one of the main pests of brassicas, and various insecticides, such as indoxacarb, are used to control it. However, frequent insecticide applications favor the selection of resistant individuals. Thus, the residual and sublethal effects of indoxacarb in two populations of P. xylostella, one collected in the field (FP) and one from the laboratory (LP), were evaluated and compared. The objective of this research was to investigate the toxicity of indoxacarb at residual and sublethal levels in a field population of P. xylostella from Brazil and a population from the laboratory. Leaf-dip bioassays showed high toxicity, with LC50 values after 48 h of 3.7 and 6.9 mg/liter for the LP and FP, respectively. Sublethal effects were indicated by significant reduction in the survival of larvae, pupae, and offspring. There was an increase in foliar consumption and a decrease in adult survival in the LP, and a decrease in fecundity in the FP. For the LP and FP population, the mean values for R0, rm, and λ for the control treatment were significantly higher than for the treatment groups (CL15 and CL25). Exposure of larvae to sublethal indoxacarb concentrations significantly reduced larval and pupal survival. Larval and pupal survival decreased as the indoxacarb concentration increased. Fecundity was significantly lower for the FP at LC15 (96.2 eggs per female) and LC25 (69.2 eggs per female) concentrations compared with the other treatments.

Cost of Production of Telenomus remus (Hymenoptera: Platygastridae) Grown in Natural and Alternative Hosts.

The study of the technical and economic aspects of rearing natural enemies is essential for its effective use as a biological control agent in the field. The aim of this study was to determine the cost of production of the parasitoid, Telenomus remus (Nixon; Hymenoptera: Platygastridae), reared in eggs of its natural host, Spodoptera frugiperda (J. E. Smith; Lepidoptera: Noctuidae), and the alternative host, Corcyra cephalonica (Stainton; Lepidoptera: Pyralidae). The insects were reared in accordance with their respective methodologies of laboratory rearing. The cost of production of this biocontrol agent is US$ 0.0004 when reared with S. frugiperda eggs and US$ 0.0002 with C. cephalonica eggs.

Quality of the Exotic Parasitoid Cotesia flavipes (Hymenoptera: Braconidae) Does Not Show Deleterious Effects after Inbreeding for 10 Generations.

Although the parasitoid Cotesia flavipes (Cameron) has proven effective in controlling sugarcane borer Diatraea saccharalis (Fabricius) for many years, concern has arisen over the quality of individuals produced at large scales. The parasitoid has been reared in laboratories in Brazil for more than 40 years, with no new introductions of new populations during that period. Since the quality of the parasitoids was not verified at the time of the species' introduction in Brazil, we do not know if there has been any reduction in quality so far. However, it is possible to determine whether the parasitoid could reduce in quality in future generations. Thus, the objective of this research was to assess the quality of these insects over 10 generations and look for evidence of any loss in quality. We used two populations: one from a biofactory that has been maintained in the laboratory for over 40 years, and an inbred laboratory population. Both were bred, and compared for 10 generations. We wanted to determine what happened to the quality of the parasitoid after 10 generations in an extreme inbreeding situation. To assure inbreeding, newly emerged females were forced to mate with a sibling. Individual females were then allowed to parasitize larvae of D. saccharalis. We performed evaluations for each generation until the tenth generation, and recorded the sex ratio, percentage emergence, number of offspring/females, and longevity of both males and females. Results of the measurements of biological characteristics demonstrated random significant differences between populations; best results were obtained intermittently for both the biofactory population and the inbred population. No significant differences across generations for the same population were observed. Thus, rearing of a C. flavipes population subjected to inbreeding for 10 generations was not sufficient to reveal any deleterious effects of inbreeding.

Development of a New Container for Storage and Release of the Parasitoid Cotesia flavipes (Hymenoptera: Braconidae).

In Brazil, the parasitoid Cotesia flavipes (Cameron) has been used as a biological control agent against Diatraea saccharalis (F.) since 1976, because of its effectiveness in reducing populations of this pest. Three million plastic cups are used annually to release C. flavipes, which remain in the environment. This study aimed to develop fully biodegradable packaging, so that releases occur without damaging the environment. The biological characteristics of C. flavipes were studied for five generations in the packaging developed (biodegradable boxes) and in the packaging currently used (non-biodegradable plastic cups and biodegradable cups), as were the costs. The results demonstrated the feasibility of using completely biodegradable and inexpensive packaging for the rearing, transport, and release of adult C. flavipes in the field.

Insecticide selectivity to two species of Trichogramma in three different hosts, as determined by IOBC/WPRS methodology.

BACKGROUND: The use of Trichogramma species is a potential key strategy in integrated pest management. However, its effectiveness depends on the use of chemicals that do not interfere with parasitism and parasite population growth. Here, a study was made of the effects of synthetic insecticides on Trichogramma pretiosum and Trichogramma exiguum in different hosts (Ephestia kuehniella, Plutella xylostella and Spodoptera frugiperda) and the influence of International Organisation for Biological Control (IOBC/WPRS) methodology in selectivity studies using different Trichogramma species. The insecticides used were commercial formulations (triflumuron at a concentration of 0.2 mL L(-1) water, etofenprox at a concentration of 0.47 mL L(-1) water and endosulfan at a concentration of 7.5 mL L(-1) water); the control treatment consisted of distilled water. Eggs attached to cardboard cards were offered to parasitoids inside glass cages. Parasitised eggs, parasitism and adult emergence rates and parasitism reduction were evaluated. RESULTS: Endosulfan and etofenprox, classified as class-4 toxic products, were extremely toxic to the parasitoids. Triflumuron, classified as a non-toxic product, was selective to the parasitoids in eggs of all hosts. CONCLUSIONS: The methodology recommended by IOBC/WPRS influenced results regarding the use of different species of parasitoids, and the use of a single parasitoid species in their experiment is questionable.