José Eudes de Morais Oliveira

Olfactory response of predatory mites to vegetative and reproductive parts of coconut palm infested by Aceria guerreronis.

The phytophagous mite Aceria guerreronis Keifer is an important pest of coconut worldwide. A promising method of control for this pest is the use of predatory mites. Neoseiulus baraki (Athias-Henriot) and Proctolaelaps bickleyi Bram are predatory mites found in association with A. guerreronis in the field. To understand how these predators respond to olfactory cues from A. guerreronis and its host plant, the foraging behavior of the predatory mites was investigated in a Y-tube olfactometer and on T-shaped arenas. The predators were subjected to choose in an olfactometer: (1) isolated parts (leaflet, spikelet or fruit) of infested coconut plant or clean air stream; (2) isolated parts of non-infested or infested coconut plant; and (3) two different plant parts previously shown to be attractive. Using T-shaped arenas the predators were offered all possible binary combinations of discs of coconut fruit epidermis infested with A. guerreronis, non-infested discs or coconut pollen. The results showed that both predators were preferred (the volatile cues from) the infested plant parts over clean air. When subjected to odours from different infested or non-infested plant parts, predators preferred the infested parts. Among the infested plant parts, the spikelets induced the greatest attraction to predators. On the arenas, both predators preferred discs of coconut fruits infested with A. guerreronis over every other alternative. The results show that both predators are able to locate A. guerreronis by olfactory stimuli. Foraging strategies and implications for biological control are discussed.

Suitability of Two Prey Species for Development, Reproduction, and Survival of Tenuisvalvae notata (Coleoptera: Coccinellidae)

ABSTRACT The coccinellid Tenuisvalvae notata (Mulsant) (Coleoptera: Coccinellidae) has been observed recently in association with the striped mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae) and the false cochineal scale Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae) in the semiarid region of Pernambuco, Brazil. The latter species are important pests of cotton and prickly pear, respectively. In this study, we tested the two scale insects as prey for T. notata. In addition, eggs of Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) were tested as possible alternative prey for rearing T. notata. In this work, the survivorship, reproduction, and predation of T. notata were investigated. The coccinellid T. notata was able to complete development only on F. virgata with 83% larval and pupal viability. Females of T. notata fed F. virgata produced 7.6 eggs a day with an eclosion rate of 61.9%. No oviposition occurred while feeding on A. kuehniella eggs. The highest consumption rate of F. virgata occurred during the last larval instar. Our results support the use of T. notata as an agent for the biological control of F. virgata, a highly polyphagous pest worldwide.

Dietary effects upon biological performance and lambda-cyhalothrin susceptibility in the multicolored Asian lady beetle, Harmonia axyridis

Considered a generalist species among the coccinellids, the multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) feeds upon small arthropods and non-prey plant products, a practice which might enhance its ability to colonize various ecosystems but carries the potential to expose it to prey quality variation and insecticide use. Thus, we examined the effect of four different diets on the development, reproduction, and response to the insecticide lambda-cyhalothrin in this species. Three groups of larvae received laboratory-reared diets: (i) eggs of Anagasta kuehniella (Zeller) (Ak); (ii) eggs of Sitotroga cerealella (Olivier) (Sc); and (iii) eggs of A. kuehniella + S. cerealella at the proportion 1:1; and one group received wild-caught cotton aphids, Aphis gossypii Glover (Ag). Notwithstanding the generalist feeding behavior of H. axyridis, development and reproduction results were superior with diets of Ag or Ak compared with the diet combining 1:1 Ak + Sc or the diet of Sc eggs only. Furthermore, the Sc diet did not result in satisfactory development and reproduction. Despite this significant variation in biological responses, insecticide susceptibility studies using adults that had been reared on these diets showed no statistically significant differences in susceptibility to the lambda-cyhalothrin.

Acaricide-impaired functional predation response of the phytoseiid mite Neoseiulus baraki to the coconut mite Aceria guerreronis

Acaricides may interfere with a myriad of interactions among arthropods, particularly predator–prey interactions. The coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), and its phytoseiid predator, Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae), provide an opportunity to explore such interference because the former is a key coconut pest species that requires both predation and acaricide application for its management. The objective of the present study was to assess the effect of the acaricides abamectin, azadirachtin and fenpyroximate on the functional response of N. baraki to A. guerreronis densities. The following prey densities were tested: 5, 10, 20, 40 and 80 preys. The type of functional response and prey handling time (Th) were not altered by the acaricides. However, the attack rate (a′) was modified by abamectin and fenpyroximate, and the consumption peak was reduced by abamectin. All of the acaricides allowed for the maintenance of the predator in the field, but exposure to abamectin and fenpyroximate compromised prey consumption.

Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae) on cotton

Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae) on cotton. The striped mealybug, Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae), is a widely distributed and polyphagous pest species, which naturally occurs on cotton plants in Brazil. This study evaluated the establishment and population growth as well as the within-plant distribution of F. virgata on four cotton cultivars: CNPA 7H (white fibers), BRS Verde, BRS Safira, and BRS Rubi (colored fibers). The experiment was conducted in a complete randomized design with four treatments (cultivars) and 18 replications of each. Thus, cotton plants of each cultivar were infested with 100 newly hatched nymphs of F. virgata. The number of adult female mealybugs and the total number of mealybugs per plant were quantified, respectively, at 25 and 50 days after infestation. The developmental and pre-reproductive periods were also determined. Furthermore, we verified the distribution of F. virgata on the plant parts at 25 and 50 days after infestation. Ferrisia virgata showed similar growth of 412-fold in the four cotton cultivars studied. Also, the nymphs were spread on infested leaves; the secondgeneration nymphs were spread and established in all plant parts. Our results characterize F. virgata as having much potential as an important cotton pest in Brazil.

Population-level effects of abamectin, azadirachtin and fenpyroximate on the predatory mite Neoseiulus baraki

The coconut production system, in which the coconut mite Aceria guerreronis is considered a key pest, provides an interesting model for integration of biological and chemical control. In Brazil, the most promising biological control agent for the coconut mite is the phytoseiid predator Neoseiulus baraki. However, acaricides are widely used to control the coconut mite, although they frequently produce unsatisfactory results. In this study, we evaluated the simultaneous direct effect of dry residue contact and contaminated prey ingestion of the main acaricides used on coconut palms (i.e., abamectin, azadirachtin and fenpyroximate) on life-history traits of N. baraki and their offspring. These acaricides are registered, recommended and widely used against A. guerreronis in Brazil, and they were tested at their label rates. The offspring of the exposed predators was also evaluated by estimating the instantaneous rate of population increase (ri). Abamectin compromised female performance, whereas fenpyroximate did not affect the exposed females (F0). Nonetheless, fenpyroximate strongly compromised the offspring (F1) net reproductive rate (R0), intrinsic rate of population growth (ri), and doubling time (DT). In contrast, fenpyroximate did not have such effects on the 2nd generation (F2) of predators with acaricide-exposed grandparents. Azadirachtin did not affect the predators, suggesting that this acaricide can be used in association with biological control by this predatory species. In contrast, the use of abamectin and fenpyroximate is likely to lead to adverse consequences in the biological control of A. guerreronis using N. baraki.

Mites on grapevines in northeast Brazil: occurrence, population dynamics and within-plant distribution

Mite pests are some of the major limiting factors affecting grape production in the world. Despite the economic importance of the grapevines and the damage to them caused by some of the phytophagous mites in northeast Brazil, little is known about the mite fauna associated with this crop. The present study aimed to identify the mite fauna associated with grapevine, to evaluate the fluctuation of the populations of the most frequent species of phytophagous mites and their associated predators over a 12-month period as well as their within-plant distribution. Considering all varieties sampled, Tetranychus urticae Koch and Oligonychus mangiferus (Rahman & Sapra) comprised 74% of phytophagous mites. Euseius citrifolius Denmark & Muma and Neoseiulus idaeus Denmark & Muma comprised more than 80% of Phytoseiidae mites. The population dynamics study was conducted in a vineyard of Sugraone and a vineyard of Itália Muscat varieties. In these fields, E. citrifolius occurred at low population levels throughout the year, whereas N. idaeus was found only when high densities of T. urticae were observed. Tetranychidae and Phytoseiidae showed the same pattern of within-plant distribution, being found in higher densities on basal and median leaves and rarely they were found on apical leaves.