Effects of Irradiation on Biology and Mating Behaviour of Wild Males of Brown Marmorated Stink Bug Using a 6 MV Medical Linear Accelerator

Abstract

The brown marmorated stink bug, Halyomorpha halys, is a pentatomid bug of Eastern Asian origin that became an economically relevant pest in the Eurasian and American continents. Management of this species is limited to use of chemical insecticides: an inefficient method due to the strong adaptability of the target pest. The sterile insect technique (SIT) is potentially a valid tactic in the search for nontoxic alternatives. In this work, we investigated the suitability of mass-trapped overwintering males, collected during the aggregation phase before the winter diapause, for their release as competitive sterile males in an SIT programme. Differently from previous studies, irradiation was applied with a linear accelerator device that produced high-energy photons. Following a similar scientific protocol with newly emerged irradiated males, the effects of X-ray irradiation on physiological parameters (longevity, fecundity and fertility) were assessed. In addition, behavioural bioassays were carried out in no-choice conditions to evaluate if irradiation interferes with mating processes. The results are very encouraging; the effects of the irradiation at 32 Gy did not differ from the controls in the longevity or fecundity of the exposed overwintering adults. The hatching rate of the eggs laid by the fertile females that had mated with the irradiated males was less than 5%. The results of behavioural bioassays showed that the irradiation did not cause a significant impact on the quality of the sterile males. More research is warranted to evaluate the mating competitiveness of sterile males in semi-field and field conditions.

Effects of γ-Irradiation on Mating Behavior of Red Palm Weevil, Rhynchophorus ferrugineus (Olivier, 1790) (Coleoptera: Dryophthoridae)

“…The aspect correlated to the short time elapsed recorded in choice tests with males irradiated at 80 Gy, needs to be better analyzed: comparing the results in no-choice conditions (no significant differences among the treatments, Figure 4a) with the results in choice conditions (just 5 min to start the mating, Figure 8b), the performance of the males irradiated at 80 Gy when another male is present is showing extremely competitive patterns; this response showing that irradiated RPW males (80 Gy) are clearly more sexually competitive than the fertile ones, confirming that the reported decline in "insect quality" can be related to the mass-rearing, handling and release practices [43][44][45]. Despite to the fact that in Figure 1 (no-choice) and in Figure 6 (choice) the mating frequency in irradiated males is following a negative physiological trend over time, the irradiated males are always performing better than the control (in particular, for the males irradiated at 80 Gy).…”

“…Concern about the suitability of implementing mass rearing facilities for this gregarious target species, new ideas and approaches are under consideration based on mass trapping, irradiation and release of large numbers of sterile males instead of multiplying them in a laboratory [43,45,47]. The classic SIT approach, based on the assessment of large mass rearing facilities is not an easy task for this species, for the long life-cycle (several months), for the presence of cannibalism behavior at the larval stages and for the complicate issue to spin a cocoon as pupation site: our preliminary data show the long life-cycle duration and the cost for the artificial diet as the most crucial aspects [12].…”

“…More recent studies show that a semi-artificial diet can be used to rear small-scale laboratory colonies [48], but probably they are not suitable for large scale SIT implementation programs. The alternative that we are taking into consideration when dealing with arthropod pests showing a clear gregarious behavior is a new approach, based on combining mass-trapping and SIT for small scale programs [43,45]. Field traps trigged with the aggregation pheromone can provide large numbers of alive RPW of both genders: keeping (or eliminating) the females and release wild males after irradiation in the environment can be a suitable and sustainable approach in peculiar, well isolated territories, such as the small island of Pantelleria or a date palm oasis in the Sahara Desert.…”

Using Gamma Irradiation to Predict Sperm Competition Mechanism in Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae): Insights for a Future Management Strategy

“…Currently, there are no field uses of the SIT in this insect order, mostly because of the risk of direct feeding damage to the host crop species from the release of sterile phytophagous hemipteran adults of an invasive pest species [ 36 ]. Nowadays, the available studies on the irradiation of hemipterans concern Halyomorpha halys Stål [ 37 , 38 , 39 ] and Nezara viridula L. [ 40 , 41 , 42 ]. In H. halys , egg sterility after the γ exposure of males has been found to be 54.3% at 16 Gy [ 38 ]; additionally, in N. viridula , the application of a dose of 16 Gy or higher can sterilize males by 99% [ 43 ].…”

“…In H. halys , egg sterility after the γ exposure of males has been found to be 54.3% at 16 Gy [ 38 ]; additionally, in N. viridula , the application of a dose of 16 Gy or higher can sterilize males by 99% [ 43 ]. Even if incomplete sterility is probably not sufficient for an eradication program, support of the use of the SIT in area-wide control programs is provided by the recording of cumulative mortality cases in F1 in previous studies on H. halys [ 37 , 38 , 39 ].…”