Adalberto Hipólito de Sousa

Ozone Toxicity and Walking Response of Populations of Sitophilus zeamais (Coleoptera: Curculionidae)

ABSTRACT n Ozone is a recognized alternative to the fumigants methyl bromide and phosphine for the control of stored product insects. However, as with fumigants in general, the potential sublethal effects of ozone on targeted insect species may compromise its efficacy and has yet to be investigated. Here, we determined ozone toxicity of 30 field-collected populations of the maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae), and assessed the walking response of adult insects from these populations to sublethal ozone exposure. Time-mortality toxicity to ozone at 50 ppm concentration in a continuous 2 liter/min flow indicated uniform susceptibility among the populations studied without any indication of ozone resistance (toxicity ratios [at LT50] > two-fold). In contrast, there was significant variation in walking activity among the maize weevil populations, which was not correlated with ozone susceptibility. This was not surprising because of the relatively uniform susceptibility to ozone among the maize weevil populations. Respiration rate affected ozone toxicity but not walking activity, whereas body mass was negatively correlated with walking activity but was not correlated with ozone toxicity. Based on our data, lower respiration rates may potentially lead to reduced ozone uptake whereas larger body mass limits walking activity. Ozone seems a promising alternative fumigant with low short-term risk of resistance development because of the high susceptibility and low variability of response to this compound. Furthermore, ozone reduces walking activity of S. zeamais that implies it likely reduces the chances of insects escaping exposure at the early stages of fumigation.

Cristalização de melão pelo processo lento de açucaramento

The experiment was carried out in the Food Technology Laboratory of the Escola Superior de Agricultura de Mossoro (ESAM), Mossoro-RN, Brazil to evaluate the possibility of processing the melon pulp as a crystallized fruit by using the us following melon varieties: Galia, Pele de Sapo, and Orange Flesh, utilizing the slow sugary process. The pulps were withdrawn in little ball form and put successively into sucrose solutions at 20, 30, 40, 50, 60 and 70°Brix, until boiling, keeping them in inactivity for 24 hours in each solution. After that, the fruits were placed in a stove at 50°C during 6 hours, reaching final humidity between 26.16 and 27.53%. Evaluations for humidity content, pH and total soluble solids were made. In addition a sensorial analysis was made. It was observed that the melon crystallization was technically feasible. Pele de Sapo melon was the best in comparison to the other types. Changing in the melon pulp colouring was not observed.

Population Development of Zabrotes subfasciatus (Coleoptera: Chrysomelidae) in Landrace Bean Varieties Occurring in Southwestern Amazonia

Abstract The common bean, Phaseolus vulgaris (L.), is one of the most important sources of protein worldwide, and Latin America is one of the recognized centers of diversity of this species. However, storage of this product after harvest is not feasible because of bruchid attacks. This study determined the accumulated normalized rate of emergence and the daily emergence rate of Zabrotes subfasciatus (Boheman) (Coleoptera: Chrysomelidae: Bruchinae) in five landrace varieties of common bean (BRL 01, SNA 01, RDR 01, RBC 01, and RBC 13) that occur in southwestern Amazonia. These varieties were selected for this study because they are well-distributed throughout the Amazonian communities. Beans of each variety were infested with 50 unsexed adults, and the insects were removed 13 d after beginning the bioassays. The adult progeny obtained from the feeding substrate were counted and removed every other day after the first emergence, until the end of the emergence period. Differences were observed in the calculated rates of development; however, the time required for development and emergence of the insects was independent. Of the five varieties of bean investigated, we observed that the RDR 01, BRL 01, and SNA 01 cultivars are resistant to Z. subfasciatus; the results indicate that the use of these three varieties can reduce problems associated with bruchid attacks and enable storage of the product after harvesting.

Aqueous extracts and oil of neem combined with neonicotinoid insecticides against Bemisia tabaci biotype B in melon

This research was aimed at evaluating nymph population density of whitefly (Bemisia tabaci biotype B) in melon plants after treatment with neem-dry-leaf aqueous extracts and neem-oil ( A. Juss.) applied alternately with neonicotinoid insecticides under field conditions. The experimental design was a randomized block, with 6 treatments and 4 replications. The treatments were control (only water); neem-dry-leaf extract at 5% (neem-dry-leaf powder 50g L-1 of water); neem oil (5.0mL L-1 water); chemicals insecticides imidacloprid (30g 25L-1 of water) and acetamiprid (5g 20L-1 of water); neem-dry-leaf extract at 5% weekly alternated with imidacloprid (30g 25L-1 of water) and acetamiprid (5g 20L-1 of water); neem oil (5.0mL L-1 of water) weekly alternated with imidacloprid (30g 25L-1 of water) and acetamiprid (5g20 L-1 of water). The efficiency of treatments was compared through of the number of nymphs recorded in leaves of melon with 35, and 50 days after planting. The less number of nymphs was registered when the neem oil was applied alternatively with the chemical treatment with efficiency of 28.58 and 7.85% in the first and second evaluations, respectively. However, the nymphs incidence was higher when the neem oil and the chemical treatment were applied separately.

FIRST RECORD FOR CATHARTUS QUADRICOLLIS AND CALLOSOBRUCHUS MACULATUS CULTURES ATTACKED BY THE MITE PYEMOTES TRITICI

Se registra la ocurrencia de Pyemotes tritici (Lagreze-Fossat & Montagne) sobre Cathartus quadricollis (Guerin-Meneville) y Callosobruchus maculatus (Fabricius), reduciendo las poblaciones de estes insectos bajo condiciones de laboratorio. Este acaro fue observado alimentandose sobre larvas y ninfas de C. quadricollis, y de adultos de C. maculatus. La toxina del acaro paraliza totalmente las larvas y los adultos atacados. El acaro P. tritici es un problema letal para produccion masal de insectos, y su erradicacion efectiva depende de una supervision periodica de las colonias de insectos. De acuerdo con los resultados, el acaro P. tritici puede ser una nueva alternativa para el control biologico de C. quadricollis y de C. maculatus en productos almacenados. Sin embargo, esta posibilidad necesita de estudios adicionales para posterior recomendacion, visto que varias especies de Pyemotes tambien pueden causar dermatitis en seres humanos.