ABSTRACT. The sugarcane borer Diatraea saccharalis is widely known as the main pest of sugarcane crop, causing increased damage to the entire fields. Measures to control this pest involve the use of chemicals and biological control with Cotesia flavipes wasps. In this study, we evaluated the insecticides fipronil (Frontline; 0.0025%), malathion (Malatol Bio Carb; 0.4%), cipermetrina (Galgotrin; 10%), and neem oil (Natuneem; 100%) and the herbicide nicosulfuron (Sanson 40 SC; 100%) in the posterior region silk glands of 3rd-and 5th-instar D. saccharalis by studying the variation in the critical electrolyte concentration (CEC). Observations of 3rd-instar larvae indicated that malathion, cipermetrina, and neem oil induced increased chromatin condensation that may consequently disable genes. Tests with fipronil showed no alteration in chromatin condensation. With the use of nicosulfuron, there was chromatin and probable gene decompaction. In the 5th-instar larvae, the larval CEC values indicated that malathion and neem oil induced increased chromatin condensation. The CEC values for 5th-instar larvae using cipermetrina, fipronil, and nicosulfuron Agrochemical-induced CEC in sugarcane borer indicated chromatin unpacking. These observations led us to conclude that the quantity of the pesticide does not affect the mortality of these pests, can change the conformation of complexes of DNA, RNA, and protein from the posterior region of silk gland cells of D. saccharalis, activating or repressing the expression of genes related to the defense mechanism of the insect and contributing to the selection and survival of resistant individuals.

Modern farming techniques have increased the crop yield, but natural habitats of the pollinator were destroyed, affecting their populations compared to native vegetation. A simple, low-cost, and efficient way to determine the presence of insecticide residues from farming is the honeybee as a bioindicator. However in Brazil, there is another species of bee, the stingless bees. The insecticide toxicity analyses the beneficial insect species as pollinators which are performed to the Apis mellifera. Stingless bees are native to tropical and subtropical zones, and they are more sensitive to pesticides than honeybees. We present some results of contamination in these bees compared to Africanized honeybees, and pose an important question Why does the pesticide industry not make assays with stingless bees too? When insecticides were in larger concentrations, bees did not feed. When the concentration of the insecticide was smaller, Africanized honeybees consumed the polluted honey, resulting in the death of some. Finally, we report several experiments concerning honeybees, and mainly stingless bees, and the effect of pesticides in them results show stingless bees are more sensitive than honeybees. Our Bee Research Group studied this point, and we hope to contribute for understanding this relation between bee, pesticide, and environment.

-Diatraea saccharalis (Fabricius) has cryptonephridial type Malphigian tubules (MT).This type of MT is characterized by the penetration of the distal part of the MT into the external walls of the rectum, which is usually lined with a perinephral membrane. The MT is divided into three differentiated regions: proximal, middle and distal. In this study, our objective was to compare the nuclear activities of each one of the three regions of the D. saccharalis MT by using a nuclear basophilic technique and critical electrolyte concentration with a toluidine blue stain at pH 4.0. This method allows differentiation of DNA/protein complexes in in situ and in vitro chromatin. MT chromatin structure in D. saccharalis is variable. Fifth instars have a more decondensed chromatin than fourth instars. The distal tubule region was the most decondensed region of the MT. Our data show an elevated genetic activity of the MT in the pre-metamorphosis period. The distal region of the MT has the highest observed activity, which may be associated with the re-absorption of useful components and the excretion of waste materials.

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