Survival and behavioural responses of the predatory ladybird beetle,Eriopis connexapopulations susceptible and resistant to a pyrethroid insecticide

Abstract

The ladybird beetle, Eriopis connexa (Germar) (Coleoptera: Coccinellidae), is one of the commonest predators of aphids (Hemiptera: Aphididae) in the cotton agroecosystem and in many other row and fruit crops in Brazil, and has been introduced into other countries such as the USA for purposes of aphid control. In addition, the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the most serious cotton pest where it occurs, including Brazil. Controlling boll weevils and other pests such as cotton defoliators still tends to involve the intense application of insecticides to secure cotton production. The pyrethroid insecticide lambda-cyhalothrin (LCT) is commonly used, but this compound is not effective against aphids; hence, a desirable strategy would be to maintain E. connexa populations in cotton fields where LCT is applied. Using populations of E. connexa resistant (Res) and susceptible (Sus) to LCT, we compared behavioural responses on treated cotton plants and under confinement on partially and fully treated surfaces, and assessed the insects' survival on treated plants compared with that of the boll weevil. The E. connexa resistant population caged on treated plants with 15 and 75 g a.i. ha-1 exhibited ≫82% survival for both insecticide concentrations compared with ≪3% and ≪17% survival for susceptible E. connexa populations and boll weevils, respectively. The response of E. connexa Res and Sus populations when released, either on the soil or on the plant canopy, indicated avoidance towards treated plants, as measured by elapsed time to assess the plant. When compared with susceptible individuals, resistant ones took longer time to suffer insecticide knockdown, had a higher recovery rate after suffering knockdown, and spent more time in the plant canopy. Based on behavioural parameters evaluated in treated arenas, no ladybird beetles exhibited repellency. However, irritability was evident, with the susceptible population exhibiting greater irritability compared with the resistant population and a subgroup comprising resistant individuals that had recovered from knockdown. The outcomes for the E. connexa Res population indicate a promising strategy for its maintenance when using the insecticide LCT in integrated pest management schemes to control boll weevil or other non-target pest of ladybird beetles in cotton fields.

High level of resistance in Anopheles arabiensis mosquito to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

“…arabiensis) resistant to pyrethroids [22]. The resistance is mediated through knockdown resistance (kdr) mutations, enhanced detoxi cation of pyrethroids by the mosquito enzymes (esterases, monooxygenases and glutathione S-transferases [23,24] and probably other unknown mechanisms such as behavioral and penetration [25,26] known to occur in other vectors [27,28] to 63.5% Human Poverty Indices (HPI) compared to 37.5 % Uganda national average [30]. Most of the populations are nomadic pastoralist.…”

Susceptibility of boll weevil to ready-to-use insecticide mixtures

“…The synergistic outcome found seems to be related to the reduction in the amount of chlorantraniliprole in the mixture, compared to the single formulation. Despite the reduction in the amount of active ingredients in the mixture, the similar toxicity to boll weevil may be related to the high susceptibility of the tested boll weevil population to lambda-cyhalothrin (SPÍNDOLA et al, 2013;RODRIGUES et al, 2013). Despite the significant reduction in chlorantraniliprole, based on LC 50 , the toxicity to boll weevil yielded by mixture with thiamethoxam was not as great as that yielded in the mixture with lambda-cyhalothrin.…”

“…Emerging adults were collected daily from field collected material, and reared in plastic 1 L pots, fed with cotton buds and young tips of cotton plants prior exposure to the insecticides. Recent studies with other objectives have determined that individuals from this area are susceptible to organophosphate, pyrethroid, and spinosyns (SPÍNDOLA et al, 2013;ROLIM, 2018).…”

High level of resistance in the mosquito Anopheles arabiensis to pyrethroid insecticides from low malaria transmission zone of Moroto district, Karamoja region, Uganda: Implication for malaria vector control

“…arabiensis) resistant to pyrethroids (Mnzava et al, 2015) [17]. The resistance is mediated through knockdown resistance (kdr) mutations, enhanced detoxification of pyrethroids by the mosquito enzymes (esterases, monooxygenases and glutathione S-transferases [3,18] and probably other unknown mechanisms such as behavioral and penetration [19,20] known to occur in other vectors [21,22]. This present study was initiated to establish distribution of major malaria vectors and their resistance status to deltamethrin, permethrin (pyrethroids) and pirirmiphos-methyl (organophosphate) insecticides in Karamoja region of Uganda.…”