Population dynamics of the predator Alloeocranum biannulipes Montrouzier and Signoret (Hemiptera: Reduviidae) feeding on the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), infesting cassava chips

Abstract

Functional and numerical responses of adult females of the predatory bug Alloeocranum biannulipes Montrouzier and Signoret (Hemiptera: Reduviidae) to density changes of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), infesting cassava chips were investigated under laboratory conditions. Starved predators were exposed to different prey density as treatments with 6 replicates. Numbers of prey consumed, eggs laid, and adults emerged as well as the hatching rates were recorded daily. When feeding on the larvae of P. truncatus, consumption increased linearly (R 2 = 0.858) with the increase in larval density. At the highest pupal density of 6 P. truncatus pupae per predator, A. biannulipes adult showed the highest consumption rates (1.67 pupae). The Holling's type I and III functional responses were observed when A. biannulipes consumed P. truncatus larvae and pupae, respectively. The attack of the predator estimated to 0.027 h −1 for larvae and 0.125 h −1 for pupae. The handling time spent on pupae by the adult predator was 0.352 h with a theoretical daily maximum predation (T/T h) of 68.18 pupae of P. truncatus. The numerical response of A. biannulipes was positively linked to pupal density, with more eggs laid per female, and higher hatching rate when exposed to higher prey densities. Efficiency of food conversion into eggs by A. biannulipes increased with decreasing larval densities and remained constant with increasing pupal densities. These functional and numerical responses exhibited by A. biannulipes suggest that this predator can effectively control P. truncatus larvae at low densities and pupae both at low and high densities. Therefore, A. biannulipes could be a good candidate for the biological control of P. truncatus.

Effect of population density on oviposition, development, and survival of Alloeocranum biannulipes (Hemiptera: Reduviidae) preying on Dinoderus porcellus (Coleoptera: Bostrichidae)

“…The number of prey items offered did not influence the hatching rate of A. biannulipes eggs, in contrast with previous observations where A. biannulipes adults were fed with P. truncatus larvae (Loko et al, 2020). As reported by Sahayaraj et al (2016), offering prey species of diverse nutritional qualities to the same predator species has resulted in different egg hatching rates.…”

“…The predator A. biannulipes, which showed Holling's functional response type II in previous studies (Loko et al, 2017), presented a strong reproductive numerical response to increasing D. porcellus larvae density. As opposed to the case where A. biannulipes females were fed with larvae of P. truncatus (Loko et al, 2020), the density of D. porcellus larvae significantly influenced the fecundity of the predator. This difference could be explained by the quality of the prey, which is the most important factor affecting the prey-predator relationship (Aragón-Sánchez et al, 2018).…”

“…Indeed, studies on the functional response of A. biannulipes feeding on larvae and pupae of D. porcellus at different densities (Loko et al, 2017), and a test on the suppressive effect of this predator with respect to D. porcellus populations showed its potential as biological agent for controlling D. porcellus in stored yam chips (Loko et al, 2019). The reduviid A. biannulipes has also proved to be a good candidate for biological control of Prostephanus truncatus Horn in stored cassava chips (Loko et al, 2020) and other storage pest species such as Corcyra cephalonica Stainton, Tribolium confusum Duval, and Anagasta kuehniella Zeller (Awadallah et al, 1984). However, prior to the efficient use of A. biannulipes as a biological control agent against D. porcellus, there is a need for information regarding its reproductive numerical response.…”