This study investigated the effects of six weeds [Amaranthus hybridus L., Desmodium tortuosum (Sw.), Euphorbia heterophylla L., Ageratum conyzoides L., Bidens pilosa L., Ricinus communis L.] and the cotton plant Gossypium hirsutum L. CNPA Precocious 1 on Podisus nigrispinus (Dallas) life history characteristics and oviposition behavior. The study begun with P. nigrispinus eggs placed on plants and caged throughout up to female death. Egg production and selected plant for oviposition by P. nigrispinus were investigated caging mated females on weeds and cotton plants simultaneously. Nymphal development of P. nigrispinus was shorter on D. tortuosum and longer on A. hybridus. Nymphal viability was not affected by any species of plant studied. Nymphs reared on R. communis produced females weighting less compared to the other plant species. The weed A. conyzoides promoted higher female fecundity compared to those females reared on D. tortuosum, E. heterophylla and R. communis. The demographic parameters net reproductive rate (R o) and mean generation time (T) of P. nigrispinus were higher for females reared on A. conyzoides, while the intrinsic rate of population increase (r m) and finite rate of increase (λ) suggest that better performance of the predator will be yielded on B. pilosa. The weed plants A. hybridus and B. pilosa were significantly preferred by P. nigrispinus females to lay eggs. These results suggest that the weeds A. conyzoides, B. pilosa and A. hybridus can benefit the colonization and maintenance of P. nigrispinus in the cotton ecosystem by phytophagy.

-The activity of Metarhizium anisopliae and Beauveria bassiana towards eggs and larvae of Tuta absoluta (Meyrick) was evaluated. Our data showed that the isolates were pathogenic to both developmental stages tested and the eggs were more susceptible than the 1 st instars. The isolates URPE-6 and URPE-19 of M. anisopliae were more pathogenic to eggs and larvae, respectively. The compatibility of these two isolates with the insecticides chlorfenapyr, spinosad, indoxacarb, abamectin, and neem were evaluated. Spinosad and indoxacarb were compatible with the two M. anisopliae isolates in all tested concentrations. At the average recommended concentration, chlorfenapyr was compatible to URPE-6 and abamectin to UFPE-19. The use of entomopathogenic fungi associated with compatible insecticides may be a useful alternative to control T. absoluta.

The combination of chemical and biological controls is a historic goal of integrated pest management, but has rarely been achieved due to lethal and sublethal impact of insecticides on natural enemies altering their performance. In this context, the susceptibility of the yellow sugarcane borer, Diatraea flavipennella (Lepidoptera: Crambidae), to the insect growth regulator lufenuron and the consequent effects upon its endoparasitoid Cotesia flavipes (Hymenoptera: Braconidae) encountering exposed but surviving larvae were studied. Neonate and 10-day-old larvae were subjected to one of seven concentrations of lufenuron (1.56, 3.12, 6.25, 12.5, 25.0, 50.0 and 100 mg a.i./L). Further, effects of lufenuron to the host larvae and to the parasitoid were assessed using low lethal LC20 and LC50. Lufenuron at concentrations up to 12.5 mg a.i./L allowed partial survival of borer larvae; and concentrations over 12.5 mg a.i./L caused 100 % larval mortality before pupation in both ages. Neonate larvae exhibited lower pupal weights only at concentrations 12.5 mg a.i./L; while 10-day-old larvae treated with the LC50 exhibited delayed development. Egg viability was reduced for adult borers from surviving larvae of both ages treated with low lethal concentrations. The parasitoid C. flavipes successfully parasitized surviving low lethal treated larvae. Among the studied life history characteristics of C. flavipes, only a delayed development was observed. The results showed that lufenuron can be effective against D. flavipennella at concentrations over 25 mg a.i./L, and that surviving larvae can be successfully parasitized by C. flavipes. The insecticide lufenuron and the parasitoid C. flavipes seem to be compatible for sugarcane borer control.

Resumo -O objetivo deste trabalho foi avaliar o efeito de seis plantas daninhas e do algodoeiro no desenvolvimento, reprodução e sobrevivência do percevejo predador Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) sob escassez parcial de presas, alimentação em intervalos de três dias, e ausência total de presas. Phytophagy by Podisus nigrispinus on cotton plants and weedsAbstract -This work evaluated the effect of six weeds and cotton plants on predatory stinkbug Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) development, reproduction and survival under partial prey scarcity, three days feeding intervals, and total absence of prey. Nymphal developmental periods under partial prey scarceness with three days of feeding intervals were higher on Ricinus communis and lower on Bidens pilosa. Partial prey scarcity did not affect nymphal viability, adult female weight and reproductive characteristics, but male weight and female longevity were reduced in Desmodium tortuosum and R. communis, respectively. Podisus nigrispinus showed better performance on Amaranthus hybridus, D. tortuosum and R. communis based on the life table parameters. Nymphs reared under total absence of prey lived longer on Ageratum conyzoides, B. pilosa, D. tortuosum and Euphorbia heterophylla; however, they did not live beyond the third ínstar. Longevity of P. nigrispinus females was improved depending on the plant available ranging from 15.7 days on Gossypium hirsutum to 29.8 days on A. conyzoides. The plant availability under total absence of prey, however, was not sufficient to endure female sexual maturation and egg production.

No abstract

A utilização de inseticidas botânicos e bioinseticidas constitui uma alternativa promissora para o manejo de Spodoptera frugiperda (J.E. Smith, 1797), na cultura do milho. No presente trabalho, objetivou-se avaliar o efeito de formulações comerciais de nim e de Bacillus thuringiensis subsp. aizawai - Bta sobre esta praga em laboratório. Lagartas de S. frugiperda com 10 dias de idade foram alimentadas com folhas de milho submersas na calda dos inseticidas Neemseto®, Natuneem® e Xentari® (B. thuringiensis subsp. aizawai Bta) nas concentrações 2,5; 5,0; 7,5; 10 mL ou g/L e testemunha (água). Os efeitos dos inseticidas dependeram da concentração utilizada, pois provocaram mortalidade crescente das lagartas, alongaram o período larval e reduziram o peso larval. Em alguns casos, também, reduziram o peso das pupas, a viabilidade pupal e a longevidade de adultos. Lagartas com 0-24 h de idade foram mais susceptíveis às concentrações de Neemseto® e Xentari® a 5 e 10 mL ou g/L, em relação às com 10 dias de idade. Com o aumento da concentração, os efeitos sobre o peso das pupas e viabilidade pupal foram, também, maiores em lagartas com 0-24 h de idade.

The present research aimed to elucidate which aspects of immune responses in Diatraea flavipennella are suppressed by the parasitoid Cotesia flavipes, thus, ensuring parasitism success. We investigated the presence of apoptosis in fat body cells through the TUNEL technique. According to the results, reduced levels of nitric oxide and phenoloxidase activity were observed in larvae parasitized for three days, and reduced total number of hemocytes, after three and seven days. An increase in plasmatocytes and decrease in spherulocytes numbers were observed in the differential count on the third day of parasitism. The number of melanized microspheres in parasitized larvae was low and indicated less intense melanization. The ultrastructural analysis confirmed the immunosuppressive effect of C. flavipes on the encapsulation response of D. flavipennella because only the formation of hemocytes capsules, adhered to the microspheres' surface, was evidenced in non-parasitized caterpillars. The effect of parasitism was also recorded on the third day with the presence of hemocytes and apoptosis in fat body cells, including aspects of degeneration in the latter. We concluded that C. flavipes suppresses cellular and humoral immunological responses in D. flavipennella and drastically affects the host's fat tissue.

The green mite, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae), is considered to be one of the key pests in cassava, Manihot esculenta Crants, leading to considerable field losses. In this study, ten Beauveria bassiana (Bals.) Vuill. and ten Metarhizium anisopliae (Metsch.) Sorok. isolates were evaluated with regard to their potential as biological control agents against adult M. tanajoa females. The total mortality percentage of M. tanajoa caused by B. bassiana ranged from 13.0 to 97.0%, with confirmed mortality rates extending from 9.0 to 91.0% and LT 50 varying from 4.2 to 17.0 days. The M. anisopliae isolates showed total mortality percentages ranging from 12.0 to 45.0% with confirmed mortality rates extending from 8.0 to 45.0%, and LT 50 varying from 8.