Differential Impact of Temperature, Release Rate, Prey Density, and Pesticides on Hyperaspis trifurcata (Coleoptera: Coccinellidae) to Optimize Integrated Management of Dactylopius opuntiae (Hemiptera: Dactylopiidae)

The current work aims to establish an integrated pest management strategy using Hyperaspis trifurcata Schaeffer (Coleoptera: Coccinellidae) to control Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae) and to assess the side effects of pesticides commonly used on this predator. The first part of this study was performed under controlled conditions at two temperatures with three prey densities and two release rates for 83 days. Under field conditions, a survival time test was conducted in a screen house (1.2 ha), where a total of 5700 predators were released on 1425 cactus plants and then monitored for a period of 23 weeks. Furthermore, eight pesticides were tested on H. trifurcata in laboratory conditions at five rates in order to define the lethal doses. Under controlled conditions, the effect of temperature on predation was not significant until 27 days after release. However, the prey density significantly impacted the predation rates from the 10th to 27th day after release (p < 0.001). The predator release rate significantly affected predation starting from the 15th day after release. The lowest median survival time based on Kaplan–Meier tests was obtained at 30 °C (the high temperature) for eight predators/cladode (27 days), but the highest was at 26 °C (the low temperature) for four predators/cladode (63 days). Depending on cochineal infestation, the effect of temperature significantly increased the predation rate from the 10th to 49th day after release, but only at a high density (50 colonies/cladode). Under field conditions, the effect of the infestation level on the survival function was significant (Log-Rank p < 0.05), and the median times were 111 and 130 days after release for low and high densities, respectively. Acetamiprid, Vaseline oil, black soap, copper oxychloride, and paraffin oil were highly toxic to H. trifurcata (>84% of mortality), and the LD₅₀ values ranged from 2.3 to 69.6% of the recommended rate. For Mancozeb at the recommended dose, the mortality rate was low (<2%). The large-scale release of H. trifurcata would be successful in the Near East and North Africa (NENA) region, provided that the use of the mentioned pesticides is avoided or at least reduced.