Distribution and metabolism of abamectin in larval stages of <i>Spodoptera littoralis</i> boisduval and <i>Heliothis armigera</i> hübner (Lepidoptera: Noctuidae)

Christie, Paul T.; Wright, Denis J.

doi:10.1002/ps.2780310212

Cited by 5 publications

(2 citation statements)

References 21 publications

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“…We predict that if larvae are more sensitive to induced responses before their P450 enzyme activities are induced, those that are switched to MeJA-treated leaf material after the P450 enzyme induction period should be less affected than those switched before enzyme activation. This design also allowed us to detect differences in sensitivity of the different larval instars towards induced defenses (Christie and Wright 1991;Satasook et al 1994) and, additionally, to test whether the direction of induction is important for its effect on herbivore fitness . Because plant nutrient status can either directly influence herbivore feeding behavior and growth rates (Soldaat and Vrieling 1992) or indirectly by influencing the strength of the induced response (Bolter et al 1998), both experiments were performed with plants grown in high-and low-nitrogen soils.…”

Section: Introductionmentioning

confidence: 99%

Induced responses in Nicotiana attenuata affect behavior and growth of the specialist herbivore Manduca sexta

Dam¹,

Hadwich

Baldwin³

2000

Oecologia

131

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Many plants employ induced responses against generalist herbivores. Specialist herbivores, however, may employ several mechanisms to overcome the negative effects of induced plant defenses. Here we test how the behavior and development of specialist Manduca sexta larvae are affected by induced responses in their natural host plant Nicotiana attenuata. On a spatial scale relevant to both the plant and the herbivore, we first determined how methyl jasmonate (MeJA)-induced responses, such as increased nicotine production, affect the tendency of larvae to leave induced plants. When larvae were allowed to move between two plants planted in one pot, they left an MeJA-treated plant faster than a control plant. When both plants in the pot were MeJA-treated, the larvae developed more slowly than when both plants were uninduced, or when the larvae had the opportunity to move to an uninduced neighbor. The sooner larvae moved from an MeJA-treated plant to an untreated neighbor, the larger the body mass they attained. This demonstrates that M. sexta larvae can compensate behaviorally for the deleterious effects of induced plant responses. These effects were observed in plants grown under both low and high N supply rates, though the effects were more pronounced under high N. To examine the consequences of the timing and the direction of the host plant switching behavior for larval development, neonate larvae were fed leaves excised from induced and uninduced plants. Larvae confined to MeJA-treated leaves had higher mortality rates and grew slower than larvae fed only control leaves. This demonstrates that MeJA-induced responses decrease growth and development of specialist herbivores that do not have the behavioral option of moving to an uninduced plant. The sooner the larvae were switched to MeJA-treated leaves, the slower their development compared to larvae fed only uninduced leaves. In contrast, the sooner larvae fed MeJA-treated leaves were switched to control leaves, the faster they developed. Again the effects of MeJA treatment were stronger in plants grown under high N supply. We propose that induced plants growing in close competition with an uninduced conspecific may offset the fitness costs of these induced responses and perhaps obtain a fitness benefit by motivating herbivores to move to their neighboring competitors.

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Section: Introductionmentioning

confidence: 99%

Induced responses in Nicotiana attenuata affect behavior and growth of the specialist herbivore Manduca sexta

Dam¹,

Hadwich

Baldwin³

2000

Oecologia

131

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“…11,15,16 Studies using radioactively labelled insecticides generally provide greater accuracy of total compound partitioning in treated insects. 3,10,15,17,18 At lethal and sub-lethal doses, toxic e †ects inducing symptoms of poisoning are seldom fully described in bioassays for insecticide potency. More frequently, such observations are found in studies on pharmacokinetics of insecticide action, although few studies have followed the time course of poisoning and concomitant insecticide levels in the insect.…”

Section: Introductionmentioning

confidence: 99%

Insecticide Penetration and Symptomology Studies on Larvae ofDiabrotica undecimpunctata howardi(Barber)

Michaelides¹,

Wright²

1997

Pestic. Sci.

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: The internal and external levels of topically applied soil insecticides, teÑuthrin, terbufos and dieldrin, to 3rd-instar larvae of the southern corn rootworm, Diabrotica undecimpunctata howardi (Barber), were monitored over 48 h. Symptomology of poisoning with 10 times the dose of the larval 72-h for LD 90 each chemical was observed over 48 h at various time points after treatment. Terbufos penetrated more rapidly than teÑuthrin or dieldrin, although internal levels of teÑuthrin and dieldrin had a longer-lasting plateau than terbufos. A 72-h treatment with teÑuthrin resulted in faster penetration and also faster dis-LD 30 appearance from the insect compared with the 10 ] 72-h dose over a 48-h LD 90 period. Recorded symptoms of poisoning included regurgitation of gut contents, defaecation and writhing and these are suggested to play an important part in voiding of the toxicants at lower (sub-lethal) treatment levels. The sub-lethal e †ects of teÑuthrin are discussed with respect to likely pest behavioural changes, such as anorectic response, after Ðeld treatment of a crop.

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Some effects of abamectin on neural activity in larval instars of Spodoptera littoralis boisduval and Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

1991

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The spontaneous action potential (AP) frequencies recorded from an in‐vivo ventral nerve cord (VNC) preparation of abamectin‐treated insects not showing signs of paralysis (asymptomatic) were significantly (P < 0.05) less than those from untreated insects for fifth‐ and sixth‐instars of Helicoverpa armigera (24 h) and Spodoptera littoralis (24 and 48 h) after topical application of abamectin. There were also significantly (P < 0.05) less APs from abamectin‐treated insects showing signs of paralysis than from asymptomatic abamectin‐treated insects. Significantly (P < 0.05) more radioactivity (and abamectin) was recovered from VNCs of larvae showing signs of poisoning (paralysis) than from asymptomatic‐treated insects. There were also significant (P < 0.001) correlations between the levels of radioactivity (as log dpm) recovered from VNCs and the AP frequency (Hz) after 24 h for both instars and species and after 48 h for S. littoralis. AP frequencies did not decline significantly (P < 0.05) in abamectin‐treated sixth‐ and fifth‐instar S. littoralis larvae until respectively 4 and 8 h after treatment. In conclusion, significant correlations were found in the present study between electrophysiological events in the VNC, visible symptoms of poisoning, and accumulation of abamectin within the VNC. An inverse relationship was found between the levels of abamectin in the VNC and the level of spontaneous nervous activity. These observations are compatible with the VNC being a target site for abamectin. However, the relative importance of the VNC versus peripheral nerves, neuromuscular junctions and muscles as target sites is not known and requires further clarification. No differences in the sensitivity of the VNC to abamectin were found between fifth‐ and sixth‐instar S. littoralis larvae, though there is limited evidence for the H. armigera VNC being less sensitive than the S. littoralis VNC to abamectin.

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Distribution and metabolism of abamectin in larval stages of Spodoptera littoralis boisduval and Heliothis armigera hübner (Lepidoptera: Noctuidae)

Cited by 5 publications

References 21 publications

Induced responses in Nicotiana attenuata affect behavior and growth of the specialist herbivore Manduca sexta

Induced responses in Nicotiana attenuata affect behavior and growth of the specialist herbivore Manduca sexta

Insecticide Penetration and Symptomology Studies on Larvae ofDiabrotica undecimpunctata howardi(Barber)

Some effects of abamectin on neural activity in larval instars of Spodoptera littoralis boisduval and Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

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