Abstract
Larval and adult populations of the Egyptian alfalfa weevil (EAW) Hypera brunneipennis (Boheman) (Coleoptera: Curculionidae) was monitored after application of the entomopathogenic fungus Beauveria bassiana in the alfalfa field (Medicago sativa L.) in two successive seasons 2014/2015 and 2015/2016. The second and last generation of the weevil on April 10, 2016, was controlled by only one application with the conidiospores of the entomopathogenic fungus B. bassiana (3 × 108 spores/ml). Accordingly, the larval population decreased from 16.07 ± 1.09 in season 2015/2016 to 7.37 ± 0.05 individuals/50 sweep net double strokes in season 2016/2017. Also, the adult weevil’s population decreased from 5.66 ± 0.8 to 2.55 ± 0.6 individuals/50 sweep net double strokes in the two seasons, respectively. 39.66% mortality rate was recorded in the Hypera brunneipennis adults aestivated under loose bark of the surrounding eucalyptus trees, which received the application of B. bassiana in the field. Another application with the fungus, targeting the second generation of the pest adults in alfalfa each season, will undoubtedly lead to a further decrease in the pest population.
Highlights
The Egyptian alfalfa weevil (EAW), Hypera brunneipennis (Boheman) (Col.: Curculionidae), is considered one of the most damaging economic insect pests attacking the Egyptian clover, Trifolium alexandrinum L., and alfalfa, Medicago sativa L., in Egypt
Larval abundance of EAW In both seasons, 2015/2016 and 2016/2017, the population abundance of H. brunneipennis larvae started from late December (December 23) to early May (May 3) recording 6 and 1 larvae, respectively (Fig. 1)
The obtained data showed that the population abundance of EAW larvae in the second season was lower than in the first one (Figs. 1 and 2)
Summary
The Egyptian alfalfa weevil (EAW), Hypera brunneipennis (Boheman) (Col.: Curculionidae), is considered one of the most damaging economic insect pests attacking the Egyptian clover, Trifolium alexandrinum L., and alfalfa, Medicago sativa L., in Egypt. Symptoms of infestation appear in winter/spring, especially in alfalfa and clover areas at field edges adjacent to eucalyptus and date palm trees (adult weevil aestivating sites). This pest is found in all alfalfa-producing areas worldwide (Cook et al 2004; Atanasova 2012). Rather than leaving the field for aestivation, El Husseini Egyptian Journal of Biological Pest Control (2019) 29:82 some adults remain in the alfalfa, mate and continue to lay eggs These eggs soon hatch, giving rise to a second generation of weevil larvae that continue to cause damage to the second and sometimes third cuttings (Cook et al 2004)
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