Cléber Antonio Baronio

Toxicities and effects of insecticidal toxic baits to control Drosophila suzukii and Zaprionus indianus (Diptera: Drosophilidae)

BACKGROUND Drosophila suzukii is a primary insect pest that causes direct damage to fruits with a thin epidermis such as strawberries, cherries and blueberries. In strawberry fields, the co-occurrence of D. suzukii and Zaprionus indianus has increased production losses. This study evaluated the toxicities and effects of insecticidal baits to control adults and larvae of both D. suzukii and Z. indianus. RESULTS Organophosphate (dimethoate and malathion), spinosyn (spinosad and spinetoram), pyrethroid (lambda-cyhalothrin) and diamide (cyantraniliprole) insecticides exhibited high toxicity to both adults and larvae of D. suzukii and Z. indianus (mortality >80%) in topical and dip bioassays. However, when the insecticides were mixed with a feeding attractant, a positive effect was observed only for adults of D. suzukii. Insecticides containing neonicotinoids (acetamiprid and thiamethoxam) and pyrolle (chlorfenapyr) caused intermediate mortality to adults of D. suzukii (40-60%) and low mortality for Z. indianus (mortality <23%); however, these compounds reduced the larval infestation of the two species by 55-86%. Botanical (azadirachtin) and sulphur insecticides exhibited low toxicity (mortality <40%) on adults and larvae of both species. CONCLUSION Dimethoate, malathion, spinosad, spinetoram, lambda-cyhalothrin and cyantraniliprole are highly toxic to both larvae and adults of D. suzukii and Z. indianus. The use of toxic baits for adults of D. suzukii could be an alternative in management of this species.

Susceptibility and Interactions of Drosophila suzukii and Zaprionus indianus (Diptera: Drosophilidae) in Damaging Strawberry.

Drosophila suzukii (Matsumura) has been recently detected causing damage to strawberries in Brazil. Infestation in strawberry culture has often been observed jointly with the presence of Zaprionus indianus Gupta. This study investigated the susceptibility of strawberries at three ripening stages to infestation of D. suzukii and Z. indianus and their interaction. In the laboratory, strawberries cv. Albion at different ripening stages (green, semi-ripe and ripe) were exposed to D. suzukii and Z. indianus for 24 h in choice and no-choice bioassays. Additionally, we evaluated the effects of mechanical damage incurred artificially or by D. suzukii oviposition on Z. indianus infestation. In no-choice bioassay, there were no significant differences in fruit susceptibility to D. suzukii infestation at different ripening stages. However, in choice bioassay, D. suzukii adults preferred to oviposit on R fruit. The presence of mechanical damage did not increase susceptibility of fruit to D. suzukii oviposition. For Z. indianus, there was greater susceptibility of R fruit in relation to SR and G fruit in both the choice and no-choice bioassays. There was a significant and positive interaction of mechanical damage and damage caused by D. suzukii to R fruit and infestation by Z. indianus, which was not observed in SR and G fruit. Although infestation of Z. indianus is related to attack damaged or decaying fruit, this work shows that this species has the ability to oviposit and develop in healthy strawberry fruit with and increased infestation level when the fruit has damage to its epidermis.

Efeito de inseticidas em diferentes fases de desenvolvimento de Grapholita molesta (Busck, 1916) (Lepidoptera: Tortricidae) e estruturas vegetais da macieira e do pessegueiro

The oriental fruit moth Grapholita molesta is one of the main pests of apple and peach trees. In this study, the mortality caused by insecticides when applied on different stages of development of G. molesta and about fruits and tops of apple and peach trees was evaluated. The insecticides acetamiprid (8g 100L -1), phosmet (100 g 100L -1), spinetoram (3.75 g 100L -1) and novalurom (4.0 g 100L -1) reduced hatching in levels above 80%, regardless of whether the application is performed before or after oviposition. The etofenprox (15 g 100L -1) was the most effective when applied after oviposition. In apple and peach tops, the insecticides acetamiprid, chlorantraniliprole (4.9 g 100 L-1), etofenproxi, phosmet, novaluron and spinetoram caused mortality of larvae over 90%. In apple fruits, the insecticides acetamiprid, chlorantraniliprole, etofenprox, phosmet, and spinetoram, caused 100, 79, 76, 97 and 100% mortality, respectively, whereas in peach fruits this control was over 85%. The insecticide novaluron caused lower mortality of larvaes when applied on fruits, compared to the application on tops. In adults, only the insecticides etofenprox and phosmet were toxic both to females (59% and 39%) and males (79% and 80%), while spinetoram was effective only in males (78%). It is concluded that insecticides etofenprox, phosmet and spinetoram were efficient in the control of G. molesta in all stages of development.

Seasonal Life Cycle of Linepithema micans (Forel) (Hymenoptera: Formicidae) in Vineyards.

Linepithema micans (Forel) is considered to be the main ant species responsible for the spread of Eurhizococcus brasiliensis (Wille), a soil scale that damages vine plants in southern Brazil. In this work, the seasonal life cycle of L. micans was evaluated in vineyards to define the most appropriate time for the application of toxic baits for control. Ant nests were transported to the laboratory in plastic bags, and individual ants were separated into groups of eggs, larvae, pupae, workers, males, and queens, recording the number of individuals per colony. The seasonal life cycle of L. micans in the vineyards began in spring with the deposition of eggs by queens. During the warm months of the year (spring and summer), it was possible to observe nests consisting primarily of eggs and pupae. During the autumn and winter months, the colonies were composed predominantly of larvae and a reduction in eggs was observed. Because the main control strategy targets the larval stage of the insect, the application of toxic baits for the control of L. micans must be performed during the winter.