Field Level Auto-inoculation of Sorghum chafer, Pachnoda interrupta (Olivier) (Coleoptera: Scarabaedae) with Metarhizium anisopliae based Microbial Bio-control Agents using Locally Affordable Traps

Sorghum chafer,<em>Pachnoda interrupta</em>, is the most serious pest of sorghum in Ethiopia destroying the entire fields at the milk stage and causing up to 100% yield loss. Current control methods entirely depend on direct spraying and baiting with insecticides which does not provide long lasting control. Efficient biological control agents such as entomopathogenic fungi that can control the pest in the breeding sites need to be developed. Traps equipped with auto-inoculation devices are important alternative methods to spread entomopathogens into insect pest populations. Field studies on fungal auto-inoculation trap development from locally available materials conducted over three feeding and two mating seasons of <em>P. interrupta</em> resulted in two efficient auto-inoculation traps (AIT1 and AIT2) baited with a five compounds blend lure which were not significantly different in catch performance with the standard Japanese beetle trap. Two selected virulent isolates of <em>Metarhizium anisopliae</em> (PPRC51 and PPRC2) were tested for field efficacy using these two designs of locally affordable auto-inoculation traps loaded with 1gm of dry conidia. Using AIT1, PPRC51 and PPRC2 induced 41% and 40% field mortality respectively, on <em>P. interrupta</em> adults under high temperature and low relative humidity conditions, while highest field viability of the two isolates five days after application was 36 % and 40 % for PPRC51 and PPRC2, respectively. Based on the catch performance, field efficacy and viability data observed, the two AIT’s are recommended for further development to be used with PPRC51 and PPRC2 for augmentation biological control in the pest’s natural habitat as a component of integrated pest management against <em>P. interrupta</em>

Metarhizium sp. isolated from dead Pachnoda interrupta (Coleoptera: Scarabaeidae) as a potential entomopathogenic fungus for the pest insect: proof-of-concept for autodissemination

Sustainable pest management requires the use of ecosystem-friendly control options (e.g. entomopathogens) coupled with target-specific application methods. Here we investigate the susceptibility of the sorghum chafer (Pachnoda interrupta, Olivier) toMetarhiziumsp., isolated from deadP. interruptaunder field conditions over several years. Target-specific trapping was achieved using Japanese beetle traps or locally made autoinoculation devices, with methyl salicylate or banana as an attractant. Of the attracted and infected beetles, 49% mortality was achieved during October 2005 and 71% during July 2006, while the corresponding mortality in control treatments was 13 and 5%, respectively. We further confirmed that the mortality of the beetles was due to the fungal treatment as 50 and 80% of the dead beetles showed mycosis, respectively. The performance of the pathogen was also investigated in an autodissemination device in 2008 and 2009, where the beetles that were attracted passed through an inoculation chamber. Of the attracted and infected beetles in the autodissemination device, 58.5% (October) and 90.9% (July) were dead within 15 days after treatment. Control mortality was only 3 and 2%, respectively. The potential for horizontal transmission was investigated, where 47% (October) and 59% (July) of the beetles exposed to the pathogen through horizontal transmission were killed. The pathogen was found to be viable for more than 3 days in the field. Our results show thatMetarhiziumsp. has potential as a biological control agent, and for achieving autodissemination using the target pest as the vector.

Effects of Sowing Date on Sunflower (Helianthus annuus) Damage by Pachnoda interrupta (Coleoptera: Scarabaeidae) and an Economic Threshold Levels for Its Management at Maiduguri, Sudan Savannah Ecological Zone of Nigeria

<em>Pachnoda interrupta</em> is one of the head-infesting insect pests of sunflower in Maiduguri. Two separate field experiment(one each for sowing date effect and threshold level) were conducted to investigate the influence of sowing date on damage and yield loss by <em>P. interrupta</em> on sunflower and the economic threshold level for its control in Maiduguri. The result for influence of sowing date experiment shows that percentage incidence of infestation was highly significant on sunflower sown on the 5^th July than other planting date except that of 26^th July. Significantly lower damage was recorded on sunflower sown on 19^th July than those on the 5^th and grain yield loss was also significantly higher on 26^th July sowings than all other dates. The results for economic threshold level experiment indicated that 2.38 and 2.36 beetles/head were the economic threshold level for flowing and milky grain stage respectively and there was a 1:4.9 cost: benefit ratio/ ha. This means that there is a 20% return for every unit of inputs. The result implies that 19^th of July is the best planting date to reduce infestations, damage and yield loss from <em>P. interrupta</em> in Maiduguri and artificial control measures should be initiated when there are 1.9 to 2.0 beetles/plant.