Developing pheromone traps and lures for Maruca vitrata in Benin, West Africa

Abstract

In previous work successful trapping of the legume podborer, Maruca vitrata Fabricius (Lepidoptera: Pyralidae), was accomplished using a synthetic pheromone blend consisting of ( E , E )-10,12-hexadecadienal, ( E , E )-10,12-hexadecadienol, and ( E )-10-hexadecenal in a 100 : 5 : 5 ratio. In the present work, experiments were conducted in cowpea fields in Benin to compare different trap designs, and other aspects of the lures. A water-trap made from a plastic jerry-can was found to be superior to commercial funnel-and sticky-trap designs, and 120 cm was the optimum height for captures. Generally, lures consisted of polyethylene vials containing 0.1 mg of pheromone. Results showed that shielding the lures from the adverse effects of sunlight with aluminium foil did not increase trap catches of M. vitrata . The degree of isomeric purity of the ( E , E )-10,12-hexadecadienal and ( E , E )-10,12-hexadecadienol blend components, in the range 73-99%, had no significant effect on captures, while lures of 80% isomeric purity showed no loss of effectiveness for up to 4 weeks. Similar results were observed with lures from a commercial source containing 0.46 mg of pheromone in the blend ratio 100 : 11 : 6 and 95% isomeric purity. Residue analysis showed that vial lures exposed for 2 weeks in the field still contained 73% of the initial amount of ( E , E )-10,12-hexadecadienal, compared to rubber septa dispensers, which only retained 22%. Females comprised 11-50% of total catches, confirming earlier, unexpected results for synthetic lures. The observations that effective traps can be made from locally available plastic containers, and that pheromone blend composition and purity are not critical, should reduce costs and improve the feasibility of traps as practical monitoring tools for M. vitrata .

Pathogenicity and performance of two candidate isolates of Metarhizium anisopliae and Beauveria bassiana (Hypocreales: Clavicipitaceae) in four liquid culture media for the management of the legume pod borer Maruca vitrata (Lepidoptera: Crambidae)

“…Fungal autodissemination has been described for other adult insect pests such as fruit flies (Dimbi et al, 2003;Dimbi et al, 2013) and leafminers (Migiro et al, 2010). There is mounting evidence that M. vitrata is attracted to synthetic sex pheromone lures (Downham et al, 2004;Hassan, 2007;Schläger et al, 2012;Srinivasan, 2012). Thus, delivering the fungal conidia along with these lures using an appropriate autoinoculation device that ensures maximum spore uptake by the insects and prolonged spore viability should have a highly effective impact on M. vitrata populations.…”

“…Additional studies using the same isolates against East African populations yielded lower than 45% mortality on eggs (S. Ekesi et al, unpublished data), suggesting the existence of host specificity of EPF to varying populations of the insect. Indeed, there is documented evidence to suggest the existence of various populations and host races of M. vitrata, and variations have been reported in the responses of populations in West Africa, Southeast Asia and South Asia to synthetic sex pheromone lures (Downham et al, 2004;Hassan, 2007;Schläger et al, 2012;Srinivasan, 2012). The difference in populations may be responsible for the lack of efficacy of Nigerian isolates of EPF to M. vitrata in East Africa.…”

Integrated pest management for cowpea–cereal cropping systems in the West African savannah

“…The first of these is attraction of substantial numbers of female moths to synthetic lures in traps as observed by Downham et al (2003Downham et al ( , 2004. The first of these is attraction of substantial numbers of female moths to synthetic lures in traps as observed by Downham et al (2003Downham et al ( , 2004.…”

“…eldanae Egg Arodokoun (1996) respectively, of the M. vitrata sex pheromone. Furthermore, the precise dose, blend ratio or isomeric purity of the EE10,12-16:Ald and EE10,12-16:OH components have been found not to be critical in achieving catches in the field (Downham et al, 2004). Downham et al (2003) extended this work by demonstrating that in field experiments in Benin, traps baited with polythene vials containing 0.1 mg of a blend of EE10,12-16:Ald, EE10,12-16:OH and (E)-10-hexadecanal (E10-16:Ald) in a 100:5:5 ratio caught significantly more males than traps baited with the major component alone, a twocomponent blend, or virgin female moths.…”

“…They also reported antagonistic effect of isomeric impurities in the synthetic pheromone on its ability to attract pests. These lures remain attractive for at least 4 weeks under field conditions, and the most effective design for traps is one produced from 5 l plastic jerry cans (Downham et al, 2004). Furthermore, the precise dose, blend ratio or isomeric purity of the EE10,12-16:Ald and EE10,12-16:OH components have been found not to be critical in achieving catches in the field (Downham et al, 2004).…”