Experimental preparations (alginate granules and mycelial mats) of the entomopathogenic Erynia neoaphidis were assessed for their capacity to cause infections in populations of Macrosiphum euphorbiae on pepper plants, in a greenhouse trial performed over 14 d. The dried preparations contained hyphal cells, which upon rehydration produced conidiophores and ejected ballistospores. Applications of alginate granules and mycelial mats on soil were more rapid in causing infections in the host population compared with foliar applications. On the last sample date, infection rates of 10–14% were obtained with foliar applications of E. neoaphidis as alginate granules and mycelial mats, respectively. With soil applications of E. neoaphidis granules and mats, infections were 23–36% after 14 d. From all sample dates, 183 cadavers were found on pepper plants treated with E. neoaphidis and 37 (= 20%) exhibited external sporulation after overnight incubation.

Comparisons were also made with single foliar sprays of Beauveria bassiana (Mycotrol WP®) and the systemic insecticide pymetrozine (Chess WP®), the latter being the only treatment to significantly reduce aphid numbers during the trial period. Treatment with B. bassiana resulted in good initial infection rates (50–60%) which declined over the period and reached the same infection level as E. neoaphidis treatments at the end of the trial. With B. bassiana, a total of 81 cadavers were found, of which 62 (= 77%) sporulated.