The carmine cochineal (Dactylopius opuntiae) is an insect-plague of Opuntia ficus-indica palm crops, causing losses in the production of the vegetable used as forage for the Brazilian semiarid animals. The objective of this work was to analyze the efficacy of plant extracts, insecticides and their combination in the control of D. opuntiae. Leaf and pod extracts of Libidibia ferrea var. ferrea, Agave sisalana leaf at concentrations 10, 25, 50, 100 and 200 mg/mL, and insecticides (chlorpyrifos, acetamiprid, thiamethoxam and lamba-cyhalothrin) at concentrations minimum, median and maximum; were applied on cladodes infested by D. opuntiae. After 10 days of treatment, the percentages of mortality and LC 50 (concentration to kill 50% of cochineal) were obtained on the stages of nymphs II and adult females. The association between the LC 50 of the plant extracts with the insecticides on the cochineal it was tested. The results showed that L. ferrea extracts were more effective against cochineal, causing the 81% of nymphal II mortality (LC 50 : 20 to 160 mg/mL) and 97% of adult females (LC 50 : 43 to 50 mg/mL), whereas the extracts of A. sisalana only controlled adult females, causing the mortality from 51 to 97% (LC 50 : 17 to 46 mg/mL). The insecticide chlorpyrifos was the most efficient on nymphs and adult females cochineal (LC 50 : 0,084 mL/L). The combination of this insecticide with the extracts promoted a percentage of mortality above 90%. The extracts presented insecticidal potential on D. opuntiae and can be tested isolated or in combination with insecticides in control of cochineal.

Opuntia ficus-indica is a cactus used as fodder for animals in arid areas worldwide. However, the palm is parasitized by the carmine cochineal scale insect (Dactylopius opuntiae) causing great damage to cactus plantations in the semi-arid region of Brazil. Leaf extracts aqueous and hydro-ethanolic of neem and citronella at concentrations of 50, 100 and 200 mg/mL, and strains suspensions of Beauveria bassiana (1 × 108 conidia/mL); were applied on cladodes infested by D. opuntiae, in the laboratory. After 10 days of treatment, the percentages of mortality were obtained on the adult females. Then, the most efficient extracts were selected in the laboratory tests for control tests in palm plantation, where 100 mL of the extracts were applied in the 100 mg/mL concentration on cladodes of palms. The results show that B. bassiana strains were not pathogenic to D. opuntiae. Only the aqueous and hydro-ethanolic neem extracts were effective in controlling the cochineal. We conclude that neem extracts are effective against D. opuntiae and can be used to control carmine scale in Opuntia ficus-indica in the field.

Lichens (Algal-Fungal association) synthesize unique chemical substances with different biological activities. Three pure lichen compounds were assayed to evaluate their potential insecticidal activity against the termite Nasutitermes corniger on Petri dishes. Usnic, fumarprotocetraric and barbatic acids were isolated and purified from the lichens Cladonia substellata, C. verticillaris and Cladia aggregata, respectively, using thin-layer and high-performance liquid chromatography for attesting their purity. Nuclear proton magnetic resonance and infrared spectrophotometry was used for their chemical characterization. After exposure, mortality of termites (workers and soldiers) was determined during 11 days period. The termiticidal effect was influenced by the exposure time and the type of member colony. The results showed that lichen substances, tested at 5, 7 and 10 mg mL-1, have a termiticidal activity (~100%) on worker termites after 8th days of treatment, in comparison with controls. However, no significant effect on soldiers was found. These findings indicate that usnic, fumarprotocetraric and barbatic acids are potential compounds for use in the control of this urban pest.

Nasutitermes corniger (Motschulsky) is an urban termite pest that is controlled by chemical applications. We investigated the effect of the association of Isaria farinosa (Holm: Fries) Fries, I. fumosorosea (Wize) Brown & Smith, and I. javanica (Frieder & Bally) Samson & Hywell-Jones with the extracts of Libidibia ferrea var. ferrea (Mart. Ex Tul.) L. P. Queiroz in the control of N. corniger. The following experiments were performed: the toxicity of aqueous and methanolic extracts on the biological aspects of fungi, action of extracts on workers and soldiers, and fungus-extract combination on workers of termite. The aqueous extracts of the leaves and pods of L. ferrea var. ferrrea were more efficient than the methanol extracts, demonstrating termiticide activity at 10, 25, 50, 100, and 200 mg mL-1, with 100% worker mortality after the third and fourth days and 100% soldier mortality by the third through sixth day. Lethal concentrations (LC50) varied from 0.624 to 0.710 mg mL-1 for workers and from 0.146 to 1.410 mg mL-1 for soldiers. The extracts were compatible with the fungal strains at the lowest concentrations. Associations of the extracts with I. farinosa ESALQ1355 demonstrated efficient control of termite workers. The results demonstrate that L. ferrea var. ferrrea extracts, either alone or in association with I. farinosa ESALQ1355, functioned in the in vitro control of N. corniger, representing a viable alternative to be further tested in controlling those termites in urban areas.