Francisca Nemaura Pedrosa Haji

Biologia, exigências térmicas e tabela de vida de fertilidade do ácaro-branco Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) em videira (Vitis vinifera L.) cv. Itália

The mite Polyphagotarsonemus latus (Banks) constitutes one of the main pest of grape crop at the Submedio Sao Francisco Valley. The objective of this work was to study the biology of the broad mite Polyphagotarsonemus latus (Banks), to determine its thermal requirements and its fertility life table in grape (Vitis vinifera L.) cv. Italy. Acclimatized chambers (BOD) were used, adjusted to the temperatures of 18, 22, 25, 28 and 32°C, relative humidity of 65 ± 10% and alternated light of 12h. Egg-adult period was 3.4 and 6.8 days for males and 3.5 and 7.4 days for females, respectively at 32oC and 18oC. At the temperatures of 18, 25 and 32oC, each female deposited, respectively, 16.5, 44.3 and 13.3 eggs. The stages of egg, larva and pupa and egg-adult period presented, respectively, thermal thresholds of 11.23, 9.45, 12.19, and 9.71°C and thermal constant of 28.51, 14.59, 8.33, and 62.73 degrees-day. The mean duration of one generation (T) was 25.6, 10.8 and 8.2 days, respectively, at the temperatures of 18, 25 and 32°C. The net reproductive rate (R0) at the temperature of 25°C was the highest, corresponding to an increase of 30.12 times at each generation. The intrinsic rate of population increase (rm) was 0.10 (18°C), 0.31 (25°C) and 0.12 (32°C) and the finite ratio of population increase (l) was 1.10 (18°C), 1.36 (25°C) and 1.13 (32°C). According to the mean temperature values, P. latus can have 95 and 99 generations/year, respectively, for the municipal districts of Petrolina, PE and Juazeiro, BA.

Floral visitors of weed plants of irrigated orchard areas

Weeds can impair yield of irrigated fruit crops, studies about their ecology being needed, especially ways of reproduction and association with insects. This work was carried out in Petrolina, PE, Brazil with the objective of identifying the floral visitors of weeds, and classifying them as pollinators and pollen and/or nectar thieves, according to their behavior. The observations were made between May and October of 1998, in 26 not consecutive days, between 7:00 am and 4:00 pm. The weeds were classified in nectariferous and polliniferous when these were visited exclusively for collection of nectar or pollen, and mixed when these were visited to collect both. A grade system was adopted for the frequency evaluation: a- number of visits >30, b - between 10 to 30, c - <10. Among the 24 weeds observed, 14 were classified as nectariferous, six as polliniferous and four were considered mixed. Among the floral visitors, the following bees were registered (Xylocopa grisescens, X. frontalis, Centris aff. perforator, Ptilotrix aff. plumata, Diadasina riparia, Apis mellifera, Trigona spinipes, Eulaema nigrita), butterflies (Ascia monuste, Papilio thoas brasiliensis, Agraulis vanillae) and hummingbirds (Phaethornis sp., Chlorostilbon aureoventris). The bees were predominant in number of species (61.5%) as well as in the frequency of visits. They acted as pollinator agents in 83% of weeds visited. The butterflies were considered nectar thieves, and they acted as pollinator agents only in the case of the species of Emilia. The hummingbirds acted as pollinators for all visited species.

Nível de dano, plantas invasoras hospedeiras, inimigos naturais e controle do psilídeo da goiabeira (Triozoida sp.) no submédio São Francisco

This study was conducted to increment the integrated management of Triozoida sp. (Hemiptera, Psylliidae) in guava plants at the Sao Francisco River Valley. The damage level, weed hosts, selectivity and effect of the thiamethoxam 10GR and 250WG in the control of psylliidae were evaluated. The experiment was carried out in an irrigated area, at Petrolina, Pernambuco, in a randomized block design with four replications. Treatments consisted of: 1) thiamethoxam 10GR applied on soil; 2) thiamethoxam 250WG sprayed weekly; 3) thiamethoxam 10GR applied on soil + thiamethoxam 250WG sprayed weekly; 4; 5; 6) thiamethoxam 250WG sprayed when 10, 20 and 30% of infested branches were reached, respectively; 7; 8; 9) thiamethoxam 10GR applied on soil + thiamethoxam 250WG sprayed when 10, 20 and 30% of infested branches were reached, respectively; and 10) control (no insecticide). The percentage of infested branches in the control treatment differed significantly from the treatments 2 (2.8%), 3 (4.3%), 4 (19.7%), 7 (13.4%), 8 (14.5%) and 9 (15.0%). When thiamethoxam was used, the population reduction of natural enemies ranged from 12.5 to 39.6%, corresponding, in the selective scale, to grades (1 = non offensive (< 25%), 2 = not very toxic (25-50%). Number and weight of fruits were similar in all the treatments. Fifty one weed species and no host of Triozoida sp. were found.

Efeito de diferentes níveis de NPK na infestação de Aculops lycopersici (Massee) (Acari: Eriophyidae), em tomateiro no Submédio do Vale do São Francisco

The effect of different levels of NPK on the infestation of Aculops lycopersici (Massee) (Acari: Eriophyidae) on tomato (Lycopersicon esculentum Mill), cultivar IPA 5, under field conditions was studied. The experimental design of randomized blocks with a factorial arrangement was used, including four blocks and utilizing four levels of N (0, 60, 120, and 180 kg/ha), three levels of P (0, 80, and 160 kg/ha), and two levels of K (0 and 120 kg/ha). The active forms of A. lycopersici were sampled weekly, 53 to 113 days after the tomato plants were sowed. Twenty five leaflets were collected from the intermediate part of the plants and an area of 1,76 cm2 of the under side of these leaflets with bigger colonies was examined. The plants fertilized with 120 kg/ha of K were more infested by A. lycopersici. There was a direct relationship between mite infestation and the levels of P applied to the soil; At a K level of 120 kg/ha the infestation increased with P levels. At N levels of 60 and 180 kg/ha the infestation increased, whereas at 120 kg/ha it was reduced. However the NP interaction presented a low effect on the infestation at higher levels of N. The levels of N and P applied to the soil were positive and significantly correlated to the content found in the tomato leaves. No significat correlation was observed with regard to K.

EFEITO DO CONTROLE CULTURAL E QUÍMICO SOBRE O ÁCARO DA NECROSE DO COQUEIRO, EM COCO-ANÃO IRRIGADO

One of the most harmful pests of coconut tree crop is the mite Aceria guerreronis. This pest damage the coconut fruits in the first development stage, causing partial or total losses in fruit production. The objective of this work was to evaluate the effect of chemical products and crop management in the control of A. guerreronis, aiming to use them in a management program for this pest. The research was carried out in Petrolina-PE from August to December, 1999. A complete randomized block design, with four treatments and four replications, was used. Each replication consisted of two plants of green dwarf coconut tree variety. Treatments were: A ¾ Cleaned plants without chemical control; B ¾ Cleaned plants with chemical control; C ¾ Plants not cleaned and with chemical control; D ¾ Plants not cleaned and without chemical control. All fruits damaged by mite were taken out from plants in the treatments with cleaned plants for three times. Fenpyroxymate, tetradifon and adhesive, at the levels 200ml, 300ml and 15ml for 100 l water, respectively, were mixed and applied for three times. Results showed that the individual uses of chemical products and crop management had efficiency of 26-87% and 64-89%, respectively, on mite control. However, the association of these two control managements showed a synergic effect on mite control with efficiency of 87-96%.